Detail Construction Manuals

1. HERMANN KAUFMANN
STEFAN KRÖTSCH
STEFAN WINTER
Edition
∂
of Multi-Storey
Timber Construction
MANUAL

3. of Multi-Storey
Timber Construction
MANUAL
HERMANN KAUFMANN
STEFAN KRÖTSCH
STEFAN WINTER
Edition
∂

4. 4
With specialist contributions from:
DI Heinz Ferk
Graz University of Technology, Faculty of Civil Engineering,
Laboratory for Building Science (LFB) at the Laboratory for
Structural Engineering (LKI)
Dipl.-Ing. Sonja Geier
Lucerne University of Applied Sciences and Arts – Engineering
and Architecture, Competence Center Typology & Planning in
Architecture (CCTP)
Prof. Dr.-Ing. Architect Annette Hafner
Ruhr University Bochum, Department of Civil and Environmental
Engineering, Chair of Resource-Efficient Building
Prof. Dipl.-Ing. Architect Wolfgang Huß
Augsburg University of Applied Sciences, Faculty of Architecture
and Civil Engineering, Industrialised Construction and Production
Technology
Dipl.-Ing. Architect Holger König
Dipl.-Ing. Architect Frank Lattke BDA
DI Daniel Rüdisser
Graz University of Technology, Faculty of Civil Engineering,
Laboratory for Building Science (LFB) at the Laboratory for
Structural Engineering (LKI)
DI Dr. techn. Martin Teibinger
Univ.-Prof. Dr. Dr. habil. Drs. h.c. Gerd Wegener
TUM Emeritus of Excellence
The authors
Univ.-Prof. DI Architect Hermann Kaufmann
Technical University of Munich, Department of Architecture,
Professorship of Architectural Design and Timber Construction
Jun.-Prof. Dipl.-Ing. Architect Stefan Krötsch
Technical University of Kaiserslautern, Faculty of Architecture,
Department of Tectonics in Timber Construction
Univ.-Prof. Dr.-Ing. Stefan Winter
Technical University of Munich, Department of Civil, Geo and Environ-
mental Engineering, Chair of Timber Structures and Building Construction
Editorial services
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Translation into English and copy-editing (English edition):
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This textbook uses terms applicable at the time of writing and
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This book is also available in a German-language edition
(ISBN 978-3-95553-353-3)
This book was compiled under the direction of the Professorship of
Architectural Design and Timber Construction at the Technical University
of Munich, Department of Architecture, www.holz.ar.tum.de
Co-authors:
Dipl.-Ing. Architect Anne Niemann (Project Manager)
Dipl.-Ing. Architect Maren Kohaus
Dipl.-Ing. FH MAS ETH MA Lutz Müller
Dipl.-Ing. Architect Christian Schühle
M. Eng. Dipl.-Ing. Architect Manfred Stieglmeier
Research assistants:
Dipl.-Ing. Architect David Wolfertstetter
M.Sc. Claudia Köhler
Student assistants from the Technical University of Munich
Tobias Müller, Moritz Rieke, Konstanze Spatzenegger, Fabia Stieglmeier
Student assistants from the University of Kaiserslautern
Sandra Gressung, Maren Richter, Sascha Ritschel

5. 5
Contents
Foreword
7
Part A Introduction
1 The development of multi-storey timber construction 10
2 Wood as a resource 14
3 Solid wood and wood-based products 18
4 Life-cycle assessment 24
5 Interior air quality – the influence of timber construction 30
Part B Support structures
1 Structures and support structures 38
2 Structural components and elements 50
Part C Construction
1 Protective functions 72
2 Thermal insulation for summer 88
3 The layer structure of building envelopes 92
4 The layer structure of interior structural components 114
5 Building technology – some special features of timber
construction
122
Part D Process
1 Planning 130
2 Production 138
3 Prefabrication 142
4 Solutions for modernising buildings 150
Part E Examples of buildings in detail
Joints in detail 160
Project examples 1–22 166
Appendix
Authors 258
Glossary 260
DIN standards 264
Literature 266
Image credits 268
Index 270
Supporters/Sponsors 272

6. 6

7. 7
added storeys, extensions and alterations.
Wood is light and easy to work with, can be
efficiently transported, and prefabricated elem-
ents can make it possible to build quickly with
a minimum of disruption.
The many interesting examples of timber build-
ings in this manual clearly demonstrate the
ways in which they have enriched architecture
in urban settings. Many of them are in fact
hybrid structures, which is by no means a retro-
grade step for timber construction. On the con-
trary, skilfully combining the proven building
materials and construction methods that are
readily available on the market to build efficient
and profitable buildings in keeping with the
performance, availability, price and design
potential required is both consistent and logic-
al. This approach has long been typical of
construction in urban spaces, if we consider
the mixture of construction methods used in
the Middle Ages, where combinations of timber
and stone made it possible to build impressive
half-timbered structures, or Wilhelminian build-
ings, which from the outside seem to be made
of solid masonry, but in fact contain a high
proportion of timber in horizontal structural
elements such as slabs and roofs.
It is this wide range of possibilities modern con-
struction offers that has inspired us to question
and expand the conventional and very narrow
categorisation of timber structures into timber
frame and panel construction and solid timber
construction. Drawing on standard practice,
this book shows the many options for combin-
ing horizontal and vertical elements that can
make building with timber such a fascinating
and creative process. Together with modern
shell structures, this is resulting in an almost
explosive expansion in the potential applica-
tions of this renewable raw material.
Using wood as a construction material also
stores carbon for the long term, creating a
carbon sink and making a positive contribu-
tion to combating global warming. Climate
change will however impact wood and wood
supplies. In future, wood as a natural building
material will be available to us in a different
mix from that currently prevailing. Supplies of
hardwood will probably grow in future, while
softwood stocks will simultaneously decline.
This will result in new and further developments
Timber construction has undergone intensive
development in recent years. The quantum
leap it has made lately is demonstrated by
the fact that a growing number of higher build-
ings are being built with timber. This classic
building material, one that modernity seemed
almost to have forgotten, is undergoing a
renaissance for various reasons. Climate
change is leading to an increasing interest
both in the wider public and among architects
and their clients in sustainable and bio-based
construction solutions that use resources effi-
ciently. Timber construction offers a better
response to this interest than other construc-
tion methods. Wood’s special tactile, visual
and olfactory qualities as a natural building
material and its outstanding strength-to-weight
ratio make timber construction increasingly
attractive in modern construction, although
the primary costs compared with common
standard solutions can be somewhat higher
than those for conventional structures, depend-
ing on the type of project. In terms of overall
economic efficiency however, modern timber
construction can already give conventional
construction a run for its money.
This Manual of Multi-Storey Timber Construc-
tion is specifically not a continuation or revised
version of the Timber Construction Atlas pub-
lished in 2003. That book focused on timber
structural engineering because of the situation
that prevailed when it was published. At that
time, few multi-storey timber buildings had
been built.
The new manual is being published in response
to a very different situation. While the use of
timber in single detached houses and agricul-
tural construction has been steadily increas-
ing for a long time, it had until recently almost
entirely disappeared from cities. This is begin-
ning to change. Initiated by committed hous-
ing cooperatives, housing societies and some
joint venture residential building projects with a
growing awareness of environmental concerns,
new multi-storey timber buildings are being
built that are making this oldest of natural build-
ing materials available for many more people
to experience. Timber construction has also
begun to make a comeback in cities because
it is very suitable for conversion and densifica-
tion measures in populous urban areas and for
in wood-based materials and a much larger
proportion of hardwood-based materials in
multi-storey timber buildings than has hitherto
been the case, with positive consequences.
Many hardwoods have much better strength
and stiffness properties, which can allow plan-
ners to work with much thinner and lighter
structural components and open up entirely
new design possibilities. Europe’s forestry
industry, sustainably practised for centuries,
shows that despite intensive use of this raw
material, a vigorous forest can be maintained
that also continues to fulfil its other functions,
ranging from air purification through water
storage up to serving as a recreational space.
Europe currently grows more wood than it
uses. In Germany, Austria and Switzerland
it would be theoretically possible to build all
new buildings with timber using about a third
of the annual wood supply.
This manual is designed to provide interested
planners and developers who have no or little
experience of timber construction with targeted
information and to help alleviate their scepti-
cism about a material that is still largely unfa-
miliar when it comes to constructing multi-storey
buildings and subject to various misconcep-
tions. Potential design options are presented
and explained based on a new systematisation
of construction methods that has been devel-
oped based on practical reality. The range of
possibilities available shows that building with
timber is no more difficult than building with
other materials. It is high time to make more
use of this readily available natural resource as
a material and integrate it more into people’s
living and working environments.
We would like to thank everyone who contrib-
uted to the creation of this book; the publish-
ers for their confidence in us, the authors for
their knowledgeable contributions, the spon-
sors for their generous support, and our project
manager Anne Niemann for her untiring com-
mitment.
Munich, May 2017
Hermann Kaufmann
Stefan Krötsch
Stefan Winter
Foreword
Fig. Zollfreilager residential buildings, Zurich (CH) 2016,
Rolf Mühlethaler

9. 9
1 The development of multi-storey
timber construction 10
Antiquity and the Middle Ages in
Eastern Asia 10
The Middle Ages in Europe 11
The modern era 12
2 Wood as a resource 14
Forestry and timber 14
The forestry and timber industry:
partners in timber construction 15
The timber resource situation and
its prospects 15
Deciduous woods: another option
in timber construction 16
Conclusion 17
3 Solid wood and wood-based
products 18
4 Life-cycle assessment 24
Timber buildings can contribute to
environmental protection 24
Carbon sequestration and substitution 25
Carbon sequestration versus an efficient
use of resources in construction 25
CO2
-efficient timber construction 26
Comparative evaluations of
conventional and timber buildings
based on life-cycle assessments 27
Conclusion 28
5 Interior air quality – the influence
of timber construction 30
A healthy indoor climate 30
Emissions in interior air 30
The influence of natural wood on
interior air 33
The impact of glued construction
timber on interior air 33
The influence of wood-based materials
on interior air 33
Strategies for managing emissions 35
Conclusion 35
Part A Introduction
Fig. A Illwerke Zentrum Montafon, Vandans (AT) 2013,
Architekten Hermann Kaufmann

10. 10
A 1.1
A 1.2 A 1.3
The development of multi-
storey timber construction
Stefan Krötsch, Lutz Müller
Since the advent of fortified cities and villages,
developments in construction have focused
on building high, multi-storey buildings, some-
times due to a lack of space inside fortifications
but also for reasons of prestige. In regions
where wood was the predominant building
material, the knowledge and manual skills for
building durable, multi-storey timber buildings
have been established since antiquity.
Even log construction, one of the oldest meth-
ods of timber construction and one practised
since the Neolithic Age, made it possible to
build buildings with several storeys. This
method was common in densely forested
regions of Asia and Europe well into modern
times and is still used in some areas. Closed,
windproof insulating walls are created by
stacking blocks or logs and by dovetailing,
lapping or notching corners and bracing
interior walls. Although tall buildings made
of horizontally stacked logs can settle signifi-
cantly, buildings of surprising height were
built in areas with highly skilled craftsmen,
as demonstrated by the example of a five-
storey residential building in the Swiss canton
of Valais (Fig. A 1.2).
Antiquity and the Middle Ages in Eastern
Asia
Influenced by the Chinese, highly-developed
woodworking techniques emerged in Japan
in the 6th century, the protagonists of which
were referred to as “master builders” and
“great craftsmen” and were held in high regard.
During the Asuka and Nara periods, the method
of frame construction developed and it was to
remain the mainstay of Japanese architecture
well into the modern era. A roof structure
secured against the effects of wind with a
heavy weight is held up by pillars attached
to notched beams to form a load-bearing
frame. The entire structure sits loosely on
base blocks without further reinforcement.
Its solid, continuous pillars can withstand
very heavy loads, while the ductility (ability to
deform without failing) of the frame and base
connections ensures very good protection
from earthquakes.
As long ago as 725, the pagoda of the Bud-
dhist Kōfuku-ji Temple in Nara, the capital of
A 1.1 Competition design for the Langelinie Pavilion,
Copenhagen (DK) 1953, Jørn Utzon
A 1.2 Five-storey building in Evolène, Valais (CH) 1958,
Follonier brothers
A 1.3 Tō-ji Temple, Kyoto (JP) 9th century (the pagoda
was rebuilt after being destroyed in 1644)
A 1.4 Pura Besakih Temple, Bali (ID) 8th century
A 1.5 Himeji Castle, Himeji (JP) 17th century
A 1.6 “Alter Bau” granary, Geislingen an der Steige (DE)
1445

11. 11
A 1.6
A 1.4 A 1.5
The development of multi-storey timber construction
Japan at that time, was constructed with five
storeys and a height of more than 50 metres.
The main hall of the world’s largest building
entirely of wood, the Buddhist temple of Tōdai-ji
in Nara, is 57.01 metres wide, 50.48 metres
deep and 48.74 metres high and was built in
745. The five-storey, 57-metre high pagoda
of the Tō-ji Temple in Kyoto, built in the 9th
century, was Japan’s tallest building at the
time (Fig. A 1.3).
The buildings of the 8th-century Pura Besakih
Temple on Bali are up to 44 metres high
(Fig. A 1.4). Each of their eleven storeys
houses a single room that is used as a shrine
for religious rituals. Their slender towers are
braced by elaborate framework connections
between the pillars and beams using a tech-
nique similar to that employed in the Japanese
structures described above.
The palaces of Beijing’s Forbidden City were
built over less than two decades in the early
15th century. At the ceremonial centre of
this gigantic building complex is the “Hall of
Supreme Harmony”, which is 35 metres high
and has a floor area of 2,400 m2
.
The 17th-century Himeji Castle in Japan, six
storeys and 31.50 metres high, was one of
the biggest multi-storey timber buildings of its
day (Fig. A 1.5).
Frame construction and the accompanying
undefined utilisation and spatial system
remained unchanged in China and Japan for
a long period. It was not until the modern era
that this millennia-old tradition ended abruptly,
with timber being completely replaced as the
primary construction material in buildings of
more than two storeys by new building mater-
ials such as steel and concrete.
The Middle Ages in Europe
Half-timbered construction was the main
method used to build buildings in central
European cities from the Middle Ages until
well into the 19th century, but it follows a
fundamentally different construction approach.
Despite their frame-like appearance, the posts
and beams interact with the bottom plates and
wall plates and function more like braced wall
slabs than a frame construction. These wall
slabs (interior and exterior walls) brace the
building without significantly activating the
ceiling slab. Ceiling joists are laid on the walls,
often following their own rhythm without regard
to the spacing of posts.
In contrast to Asian frame constructions, sup-
porting pillars do not run through the storeys
but are intercepted by the bottom plate, ceiling
joists and wall plates and are sometimes
slightly offset on each storey. This overhang
clamps the ceiling joists between the walls,
making it possible to build larger ceiling spans
and improve the roof’s vibration characteristics.
An overhang also protects the facade below it
from the weather.
Post-in-ground and post-and-beam structures
were the precursors of half-timbered build-
ings. Post-in-ground is a framed construc-
tion method using posts driven metres deep
into the earth and dug in, to serve as supports
that brace the building. The bases of the
pillars usually rot through in 20 to 30 years
and the building must then be replaced. Post-
and-beam buildings dealt with this problem
by replacing the posts with building-high pil-
lars that were no longer driven into the earth
but laid dry on a horizontal bottom plate, which
greatly prolonged the lifespan of buildings.
This technique could also be used to build
buildings several storeys high, but the height
of individual structures was generally limited
by the length of tree trunks available. Load-
bearing pillars could only be replaced at great
expense.
The advent of half-timbered construction
represented a revolution in construction.
It was now possible to build timber struc-
tures which would last several hundred years
because individual load-bearing elements
could be replaced without jeopardising the
entire structure. Half-timbered construction
also resulted in the development of a great

12. 12
Tō-ji Temple
Japan, 888
57 metres
5 storeys
Pura Besakih Temple
Bali, 8th century
44 metres
11 storeys
Hopperstad stave church
Norway, 1130
27 metres
4 storeys
Qigu Tan
China, 1420
25 metres
3 storeys
“Alter Bau” granary
Germany, 1445
21 metres
7 storeys
10 m
20 m
30 m
40 m
50 m
60 m
70 m
80 m
90 m
A 1.8 A 1.9
A 1.7
The development of multi-storey timber construction
deal of knowledge and skill involving con-
structional timber preservation that is still in
use today.
The lengthening of buildings’ lifespans and
structures comprising stacked, well-braced
storeys facilitated the construction of multi-
storey buildings.
The seven-storey former granary (Alter Bau) in
Geislingen an der Steige dates from 1445 and
is built from timber resting on a masonry base-
ment storey, proof of this construction method’s
effectiveness and durability (Fig. A 1.6, p. 11).
The modern era
Concrete and steel dominated the material
canon of classic modernism. Initially, timber
as a material for building bearing structures
no longer played any significant role. Com-
petition from suddenly widely available, non-
flammable materials relegated timber to a
building material for lower, sometimes tempor-
ary buildings.
Only since the turn of the millennium has timber
construction taken a fundamental new direc-
tion, thanks to a series of technical innovations.
In the context of a worldwide political rethink in
the face of global environmental development,
especially global warming, there has once
again been an increased focus on using timber
for multi-storey construction in central and
northern Europe.
In a wide-ranging model project in Bavaria [1]
and following new developments in Austria,
a number of three-storey timber apartment
houses were built in the 1990s (Fig. A 1.7).
Initially partly oriented towards North American
building methods, these model projects estab-
lished various construction methods that meet
central European requirements. An evalu-
ation of the results of these projects created
an impetus for more advanced research by
research institutes and timber construction
companies [2].
Technical advances and a continuously
improving legislative environment have since
resulted in new height records for timber build-
ings at increasingly short intervals. The seven-
storey e3 apartment building (Fig. A 1.8), built
in Berlin in 2008, features elements such as
timber-concrete composite slabs and an exter-
nal steel-reinforced concrete staircase that
ensure that it meets fire safety requirements.
Eight-storey buildings such as H8 in Bad Aibling
(Fig. A 1.9) and the LifeCycle Tower One in
Dornbirn followed in 2011 and 2012. The first
timber building taller than eight storeys, the
nine-storey Murray Grove Tower, was built in
London in 2008 (Fig. A 1.11). A ten-storey
apartment building, Forté Tower, opened in
Melbourne in 2012. The Via Cenni residential
complex in Milan, completed in 2013, (p. 174ff.)
is “only” nine storeys high but consists of four
residential towers linked by a two-storey plinth

13. 13
HoHo timber high-rise building
Austria, in the planning stage
84 metres
24 storeys
Architects:
RLP Rüdiger Lainer + Partner
Student residence
Canada, 2017
63 metres
18 storeys
Architects:
Acton Ostry Architects
Forté Tower
Australia, 2012
32 metres
10 storeys
Architects:
Lendlease
H 8
Germany, 2012
25 metres
8 storeys
Architects:
Schankula Architekten
Damaschke housing estate
Germany, 1996
9 metres
3 storeys
Architects:
Fink + Jocher
90 m
10 m
20 m
30 m
40 m
50 m
60 m
70 m
80 m
Time
A 1.10
A 1.11 A 1.13
A 1.12
The development of multi-storey timber construction
structure the size of a city block. In the UK,
Australia and Italy, the flammability of the
bearing structure of high-rise buildings is not
specifically regulated (as long as an adequate
period of fire resistance is ensured), so build-
ings may be built of enclosed cross laminated
timber panels.
A 14-storey building with a glued laminated
timber frame, into which prefabricated modular
rooms were set, was built in Bergen in Norway
in 2015 (Fig. A 1.12). Canada is currently home
to the world’s tallest timber building, a student
residence in Vancouver completed in 2017
(p. 166ff.). It comprises a glued laminated
timber frame with 18 storeys over its 63-metre
height. This record will however not stand for
long because the HoHo, an 84-metre-high
timber-concrete hybrid high-rise building with
24 storeys is currently being built in Vienna
(Fig. A 1.13).
There seems to be no end in sight to these
constantly accelerating developments, raising
the question of whether the increasing effort
involved makes it worth further pushing the
limits. What is certain is that timber meets the
demands made on a modern building material
in all respects. The examples from recent years
outlined above show that timber’s flammability
has long been overstated and is no longer
an obstacle to the construction of multi-storey
buildings.
Timber now seems to have taken its place in
the material canon of current construction and
could in future continue its long tradition as a
building material for tall and urban buildings.
A 1.7 Apartment building – Bavarian model project,
Regensburg (DE) 1996, Fink + Jocher
A 1.8 e3 high-rise apartment block, Berlin (DE) 2008,
Kaden Klingbeil Architekten
A 1.9 H8 high-rise apartment block, Bad Aibling (DE)
2011, Schankula Architekten
A 1.10 Increases in the heights of multi-storey timber
buildings
A 1.11 Murray Grove Tower, London (GB) 2008, Waugh
Thistleton Architects
A 1.12 High-rise apartment block, Bergen (NO) 2015,
Artec Arkitekter/Ingeniører
A 1.13 HoHo timber high-rise building, Vienna (AT)
under construction, RLP Rüdiger Lainer +
Partner
Notes:
[1] Bavarian Ministry of the Interior – Supreme Building
Authority (Pub.): Wohnmodelle Bayern – Wohnungen
in Holzbauweise. Munich, 2002
[2] For example, see section 1, May–June 2001, Wohnen
im Holzstock

14. 14
A 2.1
Wood as a resource
Gerd Wegener
Throughout human history and until well into
the 19th century, wood was indispensable as a
raw material and building material and part of
our cultural heritage. It has been used to build
buildings and ships and as a basic material
for making tools, weapons and works of art.
Until the late 19th century, wood was the most
important fuel, was used to produce a wide
range of basic chemical materials and was the
main raw material used to make charcoal and
potash for iron and glass production. Its diver-
sity of applications meant that wood was more
familiar to people than any other material, but
overuse of timber resources in the 17th and
18th centuries led to a shortage of wood and
to deforestation in Europe [1]. In response to
these abuses, Hans Carl von Carlowitz formu-
lated his fundamental principle on sustainable
forest use in 1713 – “Do not cut more wood
than will regrow” [2]. By the late 19th and into
the 20th century, wood was largely supple-
mented by other materials (steel, concrete,
steel-reinforced concrete, plastics) and new
sources of energy (coal, oil, gas, nuclear
energy) and in many areas was replaced
entirely.
Looking back over the highlights of various
cultural epochs in the context of building
with timber, the millennial significance of this
building material becomes clear. Stone Age
houses and those of the Celts built before the
common or current era, then the houses of
the Vikings, stave churches and medieval half-
timbered buildings (Fig. A 2.2) demonstrate
its importance, as do the mid-19th century
entrance hall of Munich’s main railway sta-
tion (Fig. A 2.3) and the 163-metre-high early
20th century Ismaning radio transmission
tower (Fig. A 2.4).
Timber became less important as a construc-
tion material in the first decades after the
Second World War, apart from classical appli-
cations in roof trusses, stairs and floors.
In the past 20–30 years, timber construction has
enjoyed renewed popularity and this period
could be described as the dawn of a new era
in building with timber. This development is on
the one hand due to the ecological advantages
of this renewable building material, on the other
hand to the enormous diversity of new, high-
performance wood-based and composite
materials, innovative means of joining elements
and powerful adhesives that have become
available. Current engineering services, com-
puter-based planning and industrial prefabri-
cation have also decisively contributed to
enabling architecturally sophisticated construc-
tion with timber in urban and rural areas that
is now reaching new dimensions. This type of
construction can be fast, dry and competitive
and be used to create high-quality structures,
renovate existing buildings and to build new
housing, kindergartens, schools and office and
commercial buildings up to a height of eight
storeys and more.
Forestry and timber
Resources issues in a globalised world require
us to take a local, regional and a global view of
forests and wood. Around 30% of the Earth’s
land surface, 4 billion hectares, is currently
covered with forest. Global forest cover has
however been shrinking for decades due
to slash-and-burn farming, conversion into
agricultural land and illegal logging. The rate
of forest disappearance did however slow
between 2010 and 2015. Despite 4.3 million
hectares of plantation forestry planted annually,
3.3 million hectares of forest is now lost every
year [3].
Tropical, subtropical, boreal and temperate-
zone forests are the most important forests
supplying useful timber, with natural and
virgin forest playing only a subordinate role.
In cultivating forests of the type almost exclu-
sively found in Europe there is a focus on multi-
functional, sustainable forest management,
which as well as supplying timber has a wide
range of protective and recreational functions
A 2.1 Mixed forest
A 2.2 Medieval half-timbered buildings in Einbeck (DE)
A 2.3 Railway station building, Munich (DE) built around
1850 (demolished in the 1870s)
A 2.4 Broadcasting tower in Ismaning near Munich (DE)
built in 1932 (demolished in 1983)
A 2.5 Comparison of annual consumption of different
materials
A 2.6 EU-wide wood stocks by country

15. 15
Slovakia 0.478
Czech Rep. 0.738
Austria 1.106
Italy 1.285
Hungary 0.259
Croatia 0.334
Slovenia 0.390
Finland 2.024
Poland 2.092
France 2.453
Logs, of which lumber
Concrete
[Billions
of
m
3
]
3.7
6
5
5
4
3
2
1
0
1.8
0.21
0.28
0.02
Steel Plastics Aluminium
Sweden 2.651
Germany 3.700
Wood stocks in billions of m3
Proportion of forest of all land
A 2.6
A 2.5
A 2.3 A 2.4
A 2.2
Wood as a resource
and maintains biodiversity. In contrast, the
global plantation industry (about 7% of all
forested area) mainly grows eucalyptus and
fast-growing pine species in monocultures
for the production of timber and biomass for
specific purposes such as energy generation
and the manufacture of cellulose, paper, wood-
based materials and lower-quality types of
construction timber.
The Earth’s forests provide 3.7 billion m3
(= 2.2 billion tonnes) of logs annually, 1.3 bil-
lion m3
of softwood and 2.4 billion m3
of hard-
wood. Half of this is used to generate energy
(51%), while 49% of logs are made into prod-
ucts (timber). Wood is therefore still one of
the most important renewable raw materials
on Earth and one of the three most commonly
used materials.
Figure A 2.5 shows strikingly that a world with-
out wood as a raw and construction material
and source of energy is inconceivable [4].
In the area of non-energy uses, 1.8 billion m3
of timber is turned into 440 million m3
of sawn
lumber and 390 million m3
into wood-based
materials for building and residential pur-
poses (construction, equipment and furniture).
400 million tonnes are used to produce paper
and wood pulp products [5]. By-products and
waste materials from manufacturing are put to
good use as raw materials or energy sources
(e.g. pellets).
The forestry and timber industry: partners in
timber construction
In Europe timber construction is part of the
diverse and powerful forestry and timber
industry that form a complex value chain
extending from the forestry sector through
the timber industry and down to printing and
publishing. With turnover of EUR 180 billion
and 1.1 million employees in Germany, the
sector is a heavyweight in terms of social,
resources and environmental policies as well
as the national economy. The timber indus-
try is divided into the wood industry, wood-
working trades and lumber trade. Further part-
ners in timber construction (prefabricated
timber construction, industrial timber con-
struction, carpentry, joiners, cabinetmakers
and the furniture industry) include the for-
estry, sawmilling and wood-based prod-
ucts industries and the sawn lumber, wood-
based products and wooden component
trades [6].
The timber resource situation and its
prospects
For centuries, Europe’s forests have been
cultivated and commercial forests created
by people to supply the lumber and timber
construction industries with home-grown
timber. The 28 EU member states have
180 million hectares of forests covering 41%
of their land area. Remarkably, forested area
increased by 5% from 1990 to 2010 and in
Germany by 48,000 hectares from 2002 to
2012. These forests harbour impressive sup-
plies of wood, with 3.7 billion m3
in Germany
and 22.5 billion m3
in the EU as a whole
(Fig. A 2.6). Germany has the biggest reserves
of wood in the EU after Switzerland and Austria,

16. 16
A 2.9
Annual wood growth in Germany is around 80 million m3
. 10 million m3
remains in the forest and 70 million m3
is harvested.
Of this, 45 million m3
of timber construction products could theoretically be made annually.
Around 100 million m3
of new housing (31 million m2
of
residential space) and 190 million m3
of new non-residential
buildings is built annually In Germany. 0.08 m3
of wood in
the form of timber construction products is required on average
to build each m3
of residential buildings and 0.05 m3
of timber
for each m3
of non-residential buildings.
There is 3.7 billion m3
of timber stock in Germany
Just over a third of Germany’s annual wood harvest
would be enough to build the country’s entire annual
volume of new buildings with timber.
A 2.8
A 2.7
Wood as a resource
with an average of 336 m3
/hectares. In Ger-
many 120 million m3
of surface wood biomass
regrows annually, about 80 million m3
of which
is used in the form of raw logs (Fig. A 2.9).
These figures show that Germany’s stocks of
this raw material are replete for the long term
and even growing [7]. A model calculation
came to the surprising conclusion that all the
new buildings built in Germany could be built
with a third of the country’s average sustain-
able timber harvest (Fig. A 2.9) [8].
Sustainable timber use also presupposes an
interest in maintaining and rejuvenating forests.
Combined mixed forests adapted to their spe-
cific locations and the climate will be near-nat-
of alternative softwood types such as pine
and Douglas fir will greatly increase. Beech
(+59%) and oak (+97%) will also record con-
siderable increases. There are no figures avail-
able for Europe, but it has been predicted that
deciduous and mixed forests will play a greater
role in supplying timber due to climate change.
Deciduous woods: another option in timber
construction
Since the severe windthrow due to storms
“Vivian” and “Wiebke” (1990) and the setting of
the forestry policy goal of restructuring forests
from purely conifers to near-natural mixed for-
ests adapted to their specific locations at that
time, the area of mixed forest has increased to
76% and the area of deciduous forest to 43%
in Germany. All over Europe too, the proportion
of deciduous forest has grown in recent years
by 2.5%. As well as preserving ecological
diversity, this should help to ameliorate storm
damage and the effects of climate change.
Beech is one of the most commonly used
woods and makes up 45% of total deciduous
timber stocks in Germany. Beech has long
been a classic firewood and has been used for
wood-based materials, veneers, parquetry and
stairs, furniture and interior fittings and much
more. Despite its good strength and rigidity, it
has been surprisingly little used as a construc-
tion timber, with the exception of the glued
laminated beech timber used in special pro-
jects in Switzerland since the 1970s.
As a result of the forest resource situation
described above, interest in and scientific
examination of new options for using deciduous
woods in construction – including beech, oak
and ash as well as maple, black locust and
other woods – have considerably increased in
the past few years.
A current study of research and development
(R&D) activities involving “Deciduous woods
for load-bearing structures” [10] found that in
German-speaking countries, since 2000, over
50 R&D projects have worked on or are working
on sorting, strength properties, bonding and the
development of new wood building products.
Innovative deciduous timber building products
ural, stable forests characterised by biodiversity
(with over 50 types of trees) that produce more
hardwood and increasing proportions of dead
and decaying wood.
Germany’s current forest development and
timber resource modelling (Waldentwicklungs-
und Holzaufkommensmodellierung – WEHAM)
[9] has forecast a potential supply of around
80 million m3
of raw logs per year for the next
40 years, so timber stocks in German forests
will grow to 3.9 billion m3
. Potential supplies
of raw spruce logs, the most important con-
struction timber, which now makes up 44%
of the raw log supply, are forecast to decline
by 2027 to around 35%, while the proportion

17. 17
A 2.10
Wood as a resource
include glued laminated timber (Fig. A 2.7),
laminated hybrid timber (beech/spruce), and
laminated veneer lumber (Fig. A 2.8). These
products have been widely approved by build-
ing inspection authorities and their use in tim-
ber construction has expanded. Deciduous
wood is 1.5 to 3 times stronger than spruce
wood, so products made with it enable engi-
neers and architects to plan structures with
much more slender dimensions.
Although these are currently still new, niche
products and used mainly in innovative con-
struction projects (Fig. A 2.10), given the
resource situation of deciduous wood that can
be expected in coming years as a result of for-
estry restructuring and climate change, they
may have great potential. Targeted marketing
activities and a growing number of completed
construction projects will further promote the
use of deciduous wood products in building.
Conclusion
People have tended to and shaped our culti-
vated and commercial forests for centuries,
making them cultivated ecosystems. Given the
challenges of sustainability, climate protection
and the transition to the use of more ecologi-
cally responsible energy and materials, forests
will become increasingly important as a habitat,
an economic resource and as repositories and
suppliers of raw materials, energy and carbon.
Together with the resource-saving and energy-
efficient use of wood, as exemplified in building
with timber, the value-added chain from the
forest to timber products and timber buildings
represents a unique symbiosis of nature, tech-
nology and culture. When society and policy
makers take the transition to an economy based
on sustainable and renewable resources ser-
iously, wood will play a major role in it as a raw
material and a building material. Sustainable
forestry ensures a long-term, ecologically com-
patible supply of this unique natural material.
Only maintenance of woodlands and the use
of timber will preserve our forests as cultivated
ecosystems, as stores of carbon und energy
and not least as sources of raw materials in the
long term.
Notes:
[1] Radkau, Joachim: Holz. Wie ein Naturstoff Ge-
schichte schreibt. Munich, 2012
[2] Carlowitz, Hans Carl von: Sylvicultura oeconomica.
Munich, 2013
[3] FAO (Pub.): State of the World’s Forests. Rome,
2014
[4] FAO (Pub.): Yearbook Forest Products 2013. Rome,
2015
The European Cement Association: CEMBUREAU,
Cement & Concrete: Key facts & figures 2014
World Steel Association: Steel Statistical Yearbook
2015
Plastics Europe: Plastics – the Facts 2015
The International Aluminum Institute: Historical
Aluminium Inventories (1973–2014). 2014
[5] FAO (Pub.): Yearbook Forest Products 2013. Rome,
2015
[6] Becher, Gerhard: Clusterstatistik Forst und Holz.
Tabellen für das Bundesgebiet und die Länder.
2000 to 2012. Thünen Working Paper 32, November
2014
[7] EUROSTAT: Forestry Statistics 2015
[8] EUROSTAT: Forestry Statistics 2015
Federal Ministry of Food and Agriculture (Pub.) The
Forests in Germany. Selected Results of the Third
National Forest Inventory, Berlin 2014
[9] Thünen scientists have calculated the amount of tim-
ber forests will supply in the next forty years, Thünen
Institute. https://www.thuenen.de/de/infothek/
presse/pressearchiv/pressemitteilungen-2015/
thuenen-wissenschaftler-berechnen-das-holzange-
bot-der-waelder-in-den-kommenden-vierzig-jahren/
Press release, 29.06.2015
[10] Wehrmann, Wiebke; Torno, Stefan: Laubholz für
tragende Konstruktionen. Cluster-Initiative Forst und
Holz in Bayern GmbH (Pub.)
http://www.cluster-forstholzbayern.de/images/
Laubholzinnovationsverbund/Ergebnisse/Broschre_
Laubholz_tragende-Konstruktionen_2015_07.pdf
A 2.7 Beech glued laminated timber
left: no heartwood colouring, right: with heart-
wood colouring
A 2.8 Baubuche Pollmeier beech laminated veneer
lumber
left: S board, right: S/Q board
A 2.9 Timber stocks, annual increase and wood re-
quired to build the entire annual volume of new
buildings in timber
A 2.10 Factory hall, Probstzella (DE) 2016, F64 Archi-
tekten

18. 18
Solid wood and wood-based
products
Anne Niemann
Many new solid wood products and wood-
based materials have been developed
as a result of the industrialisation of timber
processing. This chapter offers an over-
view of the most important properties of the
timber products currently most commonly
used.
Solid wood products
The use of wood has a long history in con-
struction. Finger jointing and gluing individual
lengths of timber can extend their spans and
increase their load-bearing capacity. Drying
timber reduces its subsequent shrinkage and
the risk of fungal infestations.
Wood-based materials
Wood-based materials are made by bonding
wood (in the form of planks, sheets, chips
or fibres) in a wet or dry process, often with
the help of adhesives. In so doing, the bene-
ficial properties of wood can be selectively
enhanced. The development of stress-resistant
products has made a significant contribution to
the construction of modern multi-storey build-
ings using wood.
Technical rules
The EU construction product standards allow
only products whose usability has been
proven. This is especially significant for those
considering the use of wood-based materi-
als, because their appropriateness is not
easy to determine due to the wide range of
products available. Product properties are
described in EN product standards, while
ETAs, European Technical Assessments, pre-
scribe more detailed requirements. Products
that are not authorised and verified for use
require a separate specific proof of service-
ability.
Types of wood
Softwoods and hardwoods have very different
structures so are used for different purposes.
Climate change is leading to an increased use
of other types of woods and hardwoods from
deciduous trees in timber construction (see
“Wood as a resource”, p. 14ff.).
Adhesives, bonding agents, additives
Bonding agents can be used to help press
sheets, chips or fibres together to form wood-
based materials. Adding other substances
can influence the materials’ performance
when exposed to fire and moisture and mod-
ify their load-bearing capacity. Bonding
agents made of renewable raw materials
are currently being developed but do not
yet play any notable role in the wood-based
materials industry (see “Interior air quality –
the influence of timber construction”, p. 30ff.).
Bulk density/specific weight [kg/m3
]
A timber’s essential technological properties
such as strength, thermal conductivity or hard-
ness depend on its bulk density. Wood’s bulk
density is determined by its moisture content
(changes to its mass and volume due to swell-
ing and shrinkage) and the position the wood
came from in the log.
Fire performance
The European fire performance classes
developed out of decisions made by the
European Commission when establishing fire
performance classes for specific construction
products and charring rates in accordance
with DIN EN 1995-1-2 (Eurocode 5).
Bending or flexural strength fm,k
[N/mm2
]
Wood’s bending strength is a measure of its
resistance to a force bending it. Wood with
higher bulk density will have greater bending
strength and wood with higher moisture content
has less bending strength.
Water vapour diffusion resistance – μ
Porous materials usually have a lower μ-value
than dense ones. The lower the μ-value,
the lower a building material’s water vapour
diffusion resistance will be and the higher
the μ-value the more resistant to vapour
the material will be. Vapour diffusion-regulat-
ing layers required in construction can be
made by using a wood-based material contain-
ing a high proportion of adhesive (Fig. C 3.3,
p. 93).
Thermal conductivity [W/mK]
Wood’s thermal conductivity depends mainly
on its bulk density, moisture content and
grain direction. Simplified calculation values
as prescribed in DIN 4108 must be used in
establishing a practical verification of thermal
insulation.
Carbon content [kg/m3
]
The amount of carbon stored in timber prod-
ucts is converted into a CO2
content figure
as per DIN EN 16449. The higher the figure,
the more carbon is stored in the structural
component, which helps to alleviate its impact
on the global climate. When the structural
component is used to produce energy, the
carbon is released. A cascading or multiple
use of wood in several steps delays this pro-
cess (see “Renewable raw materials and
carbon sequestration”, p. 25).
Global warming potential (GWP) [kg CO2
eq.]
Greenhouse gas emissions are currently the
most important indicator in the climate debate.
Global warming potential measures the poten-
tial contribution of a material to warming layers
of air near the ground, i.e. its impact on the
greenhouse effect. The figure is specified rela-
tive to the global warming potential of carbon
dioxide (CO2
). The lower the CO2
-equivalent
figure is, the lower its potential effect on global
warming and related environmental effects
will be. The figure specified refers to the pro-
duction of the timber product (see “Life-cycle
assessment”, p. 24).

19. 19
a
g
m
j
p
b c
h
n
k
q
d e
i
o
l
r A 3.1
f
Solid wood and wood-based products
A 3.1 Common solid wood products and wood-based
materials
a Solid wood, sawn softwood/sawn hardwood
b Finger-jointed solid timber/solid construction
timber
c Double and triple laminate beams
d Glued laminated timber
e Lightweight timber beams/supports
f Cross laminated timber
g Three-ply laminate sheeting
h Single-ply sheeting
i Veneered plywood
j Beech veneer plywood
k Laminated veneer lumber (LVL)
l Medium-density fibreboard (MDF)
m Porous wood fibreboard
n Cement-bonded particle board, chipboard
o Chipboard, particle board
p OSB board
q Long span lumber (LSL)
r Lightweight wood wool construction board (WW)
A 3.2 Comparison of common solid wood products and
wood-based materials showing aspects relevant
to use

20. 20
Solid wood and wood-based products
Material Components Name Technical rules Wood types Main application(s) Other
applications
Solid
wood
products
Solid wood –
bar-shaped
materials
Solid wood Solid softwood timber DIN EN 14081-1, strength grading
of wood according to DIN 4074-1
and DIN EN 1912, strength class-
es in DIN EN 338, grading by
appearance in DIN EN 1611-1
Spruce, fir, pine,
larch, Douglas fir
Load-bearing structures,
formwork, cladding,
ceilings, walls, roofs,
framing
Civil engineer-
ing, timber
structural
engineering
Solid hardwood timber DIN EN 14081-1, strength grading
of wood according to DIN 4074-5
and DIN EN 1912, strength class-
es in DIN EN 338, grading by
appearance in DIN EN 975-1
Beech, oak,
more rarely
poplar, maple,
alder, birch,
cedar, ash,
eucalyptus
Structural reinforcement for
interiors, superior visual
qualities
Timber structural
engineering
Finger-
jointed
solid wood
Construction timber DIN EN 15497 and applica-
tion standard DIN 20000-7;
maximum moisture content
18%, dimensional accuracy
and stability, appearance,
surface qualities, taking pre-
ferred cross sections and
lengths into account
Spruce, fir, pine,
larch, Douglas fir
Load-bearing cross sec-
tions for ceilings, walls,
roofs and framing sections
Stacked element
Laminated
beams
Double/triple laminated
beams
Strength grading as for sawn
lumber, DIN EN 14080 or proof
of appropriateness according to
approval Z-9.1-440
Spruce, fir, pine,
larch, Douglas fir,
poplar
Visible wall, ceiling and
roof structures with large
cross sections
–
Glued laminated timber Strength grading as for sawn
lumber, DIN EN 14080 and appli-
cation standard DIN 20000-3
Spruce, fir, pine,
larch, Douglas fir,
western hemlock,
cedar
Universal applications for
all bar-shaped structural
components, ceiling elem-
ents, long-span structural
components subject to
heavy loads
Straight and
curved beams
with very stable
forms and high
visual quality
Mixed
product
Composite
beams
Lightweight timber beams/
supports
According to ETAG 011 Flanges: mainly
construction timber
sorted according
to strength, glued
laminated timber
or laminated veneer
lumber; webs:
mainly OSB or hard
wood fibreboard
Wall supports, ceiling
and roof beams, framing
with high thermal insulation
requirements
Supports
for concrete
formwork
Wood-based
materials
Laminated
materials
Planks Cross laminated timber According to approval Spruce, fir; more
rarely pine, larch,
Douglas fir
Non-load-bearing and
load-bearing structural
elements, sheeting or
panel elements, walls,
ceilings and roofs
Non-load-
bearing walls
Three-ply sheeting
(SWP-L3)
DIN EN 13353
DIN EN 13986
According to approval
Softwoods, esp.
spruce, Douglas fir
Non-load-bearing, load-
bearing and reinforcing
planking for walls, ceilings,
roofs, box elements and
facade cladding
Formwork,
interiors,
furniture
Single-ply sheeting
(SWP-L1)
DIN EN 13353
DIN EN 13986
According to approval
Softwoods, esp.
spruce, Douglas fir;
more rarely hard-
woods: maple,
beech, oak, alder
Furniture and interiors,
visible surfaces
–

21. 21
A 3.2
Solid wood and wood-based products
Proportion
of additives
[kg/m3
]
Adhesive, bonding
agent, aggregate
Bulk density/
specific weight
[kg/m3
]
Fire per-
formance
Bending strength
fm,k
[N/mm2
]
Water vapour
diffusion resistance
μ (dry/damp)1)
Thermal
conductivity
 [W/mK]2)
Carbon
content
[kg/m3
]
GWP [kg
CO2
-eqv/m3
]
A1 to A33)
– None Based on DIN EN 350:
Spruce 440–470
Fir 440–480
Pine 500–540
Larch 470–650
Douglas fir 470–550
Cedar 450–600
Calculated bulk density
from DIN EN 338 for di-
mensioning and design
and from DIN EN 1991
for loading assumptions
D-s2, d0 Strength and rigidity
values as per
DIN EN 14081-1
and strength class
C14–C50 as per
DIN EN 338
50/20 Spruce 0.09–0.12
Fir 0.10–0.13
Pine 0.12–0.14
Larch 0.11–0.13
Douglas fir 0.12
Cedar 0.09
216.3 -735
– None Based on DIN EN 350:
Beech 690–750
Oak 650–760
Poplar 420–480
Maple 610–680
Alder 500–550
Birch 550–740
Ash 680–750
Eucalyptus 540–900
calculated bulk density
from DIN EN 338 for di-
mensioning and design
and from DIN EN 1991
for loading assumptions
D-s2, d0 Strength and rigidity
values as per
DIN EN 14081-1
and strength class
D18– D80 as per
DIN EN 338
50/20 Beech 0.15–0.17
Oak 0.13–0.17
Poplar 0.12–0.13
Maple 0.15
Alder 0.15–0.17
Birch 0.14
Ash 0.15–0.17
Eucalyptus
0.13–0.24
340 -1,1204)
0.5 Polyurethane adhesive
(PUR) or melamine-urea-
formaldehyde (MUF)
resin + curing agent;
rarely: phenol-resorcinol-
formaldehyde (PRF)
adhesive
Depending on the type
of wood
D-s2, d0 Strength and rigidity
values as per
DIN EN 14081-1
and strength class
C14 – C50 from
DIN EN 338
50/20 0.13 (average)
depending on the
type of wood and
its bulk density
219.83 -712
5 Melamine-urea-formalde-
hyde (MUF) resin +
curing agent or poly-
urethane (PUR); rarely:
phenol-resorcinol-formal-
dehyde (PRF) resin or
emulsion-polymer-iso-
cyanates (EPI)
Depending on the type
of wood
D-s2, d0 Characteristic grain-
parallel bending
strengths as per DIN
EN 14080 between
20 and 32 N/mm2
50/20 0.13 (average)
depending on the
type of wood and
its bulk density
221.14 -674
8.8 Melamine-urea-formalde-
hyde (MUF) resin + cur-
ing agent or polyurethane
(PUR); rarely: phenol-
resorcinol-formaldehyde
(PRF) or emulsion-poly-
mer-isocyanates (EPI)
Depending on the type
of wood
D-s2, d0 Characteristic grain-
parallel bending
strengths as per DIN
EN 14080 between
20 and 32 N/mm2
50/20 0.13 (average)
depending on the
type of wood and
its bulk density
222.46 -650
– Adhesive as specified
in DIN EN 301 and
DIN EN 15425
Depending on the
type of wood and its
constituents
Deter-
mined by
materials,
usually
D-s2, d0
According to
approval
50/20 From EN 13986
0.13
n.d. n.d.
7.5 Polyurethane (PUR) or
melamine-urea-formal-
dehyde (MUF) resin +
curing agent; rarely:
emulsion-polymer-iso-
cyanates (EPI)
Depending on the type
of wood
D-s2, d0 According to
approval
50/20 0.13 (average)
depending on the
type of wood and
its bulk density
215.12 -632
17.8 Melamine-urea-formalde-
hyde (MUF) resin
400–500 D-s2, d0 Parallel to the surface
grain 12–35, perpen-
dicular to the surface
grain 5–9
50/20 0.09–0.13
depending on
bulk density
221.9 -642
1.5 Melamine-urea-formalde-
hyde (MUF) resin
400–500 (figures for
hardwoods vary)
D-s2, d0 DIN EN 13353:
parallel to the
grain 40 (figures for
hardwoods vary)
50/20
(figures for
hardwoods vary)
0.09–0.13
Depending
on class
(figures for hard-
woods vary)
220
(figures for
hardwoods
vary)
-712
(figures for
hardwoods
vary)

22. 22
Solid wood and wood-based products
Material Components Name Technical rules Wood types Main application(s) Other
applications
Veneers Veneered plywood DIN EN 636
DIN EN 13986
According to approval
DIN EN 635-3
Spruce, pine,
Aleppo pine, Doug-
las fir, hemlock,
mahogany, African
cherry
Load-bearing ceilings and
walls, load-bearing and
bracing planking for walls,
ceilings and roofs
Weather-proof
cladding,
formwork,
scaffolding,
interiors,
furniture
Beech veneer plywood DIN EN 636
DIN EN 13986
According to approval
DIN EN 635-2
Beech Load-bearing ceilings and
walls, load-bearing and
bracing planking for walls,
ceilings and roofs, very
high strength
Weather-proof
cladding,
formwork,
scaffolding,
interiors,
furniture
Laminated veneer lumber
(LVL)
DIN EN 14279
DIN EN 14374
According to approval
Spruce, beech,
pine, Douglas fir
Load-bearing structures,
beams, supports, flanges
and struts of truss beams
and spatial trusses,
support structures for
large halls
Interiors,
furniture
Wood-based
materials
Strand,
chip and
fibre-based
materials
Strands Parallel strand lumber (PSL) According to approval Poplar, Douglas fir,
pine
Applications with extreme
structural requirements
e.g. bottom plates, edging
boards or lintel areas, wall,
roof and ceiling plates,
supports and beams
Floor and
ceiling panels
Oriented strand board (OSB) DIN EN 13986
DIN EN 300
DIN EN 12369-1
According to approval
Pine, Aleppo pine,
Douglas fir, alder,
poplar
Load-bearing walls,
load-bearing and bracing
planking for floors, walls,
ceilings, box elements
and roofs (outside with
weather protection), webs
of Å-beams
Mounting panels
for flooring,
concrete form-
work, interiors,
furniture
Chipboard DIN EN 13986
DIN EN 312
DIN EN 12369-1
According to approval
Pine, spruce,
beech, birch, alder,
ash, oak, poplar,
chestnut
Can be universally used
for non-load-bearing, load-
bearing and bracing plank-
ing and as filling panels in
timber frame construction
Interiors,
furniture
Cement-bonded chipboard DIN EN 13986
DIN EN 634
According to approval
Spruce, fir,
softwood
chips bonded
in cement
Fire-resistant panels,
load-bearing and bracing
planking for interiors and
exteriors, facade cladding
Non-load-
bearing interior
walls, sound
and thermal
insulation
Fibre-based
materials –
fibres
Fibres Medium density fibreboard
(MDF)
DIN EN 622-5
DIN EN 13986
DIN EN 316
According to approval
Spruce, pine,
fir, beech,
birch, poplar,
eucalyptus
Interiors, acoustic
elements, furniture
Limited use as
load-bearing and
bracing planking
and to make wall,
ceiling and roof
panels
Porous panels DIN EN 13171
DIN EN 622-4
DIN EN 13986
DIN EN 316
According to approval
Spruce, fir,
pine, beech,
birch, poplar,
eucalyptus
Insulation inside and out
and between frames and
rafters of walls and roofs,
insulation of partition walls,
footfall sound insulation
Underlay boards
for roofs or to
make the build-
ing envelope
more windproof
Wood wool Wood wool Lightweight wood wool board
(WW)
DIN EN 13168 Spruce, pine,
mainly softwoods
Plaster base for ceilings
and soffits, acoustic panels
for soundproofing
Interior and
exterior planking,
thermal insula-
tion in summer
1)
Figures from DIN EN ISO 10456 2)
for a 15% moisture content, perpendicular to the grain/board direction
3)
The biogenic carbon stored in the product is contained in Module A1–A3. The amount of stored carbon is eliminated from the system when a product in Module C3 is disposed
of, either as CO2
(use in generating energy) or still bound into the old wood. All modules must be considered in an ecological life-cycle assessment.
4)
1 m3
of hardwood contains about 1.5 times as much biogenic carbon as softwood, so the GWP (A1–A3) figure for hardwood is much higher than it is for softwood mainly for this
reason. Considering the wood over its entire life cycle qualifies this figure somewhat. Hardwood processing uses much more primary energy so it produces more greenhouse
gas emissions.

23. 23
A 3.2
Solid wood and wood-based products
Proportion
of additives
[kg/m3
]
Adhesive, bonding
agent, aggregate
Bulk density/
specific weight
[kg/m3
]
Fire per-
formance
Bending strength
fm,k
[N/mm2
]
Water vapour
diffusion resistance
μ (dry/damp)1)
Thermal
conductivity
 [W/mK]2)
Carbon
content
[kg/m3
]
GWP [kg
CO2
-eqv/m3
]
A1 to A33)
89.5 Melamine-urea-formal-
dehyde (MUF) resin or
phenol-formaldehyde
(PF) resin
450–580 D-s2, d0 Depending
on the class
5–120
200/70 0.11–0.15,
depending on
bulk density
340 -350.9
89.5 Melamine-urea-formal-
dehyde (MUF) resin or
phenol-formaldehyde
(PF) resin
720–780 D-s2, d0 Depending on the
class 5–120
220/90 0.14–0.18,
depending on
bulk density
340 -350.9
56.8 Melamine-urea-formal-
dehyde (MUF) resin or
phenol-formaldehyde
(PF) resin
480–580 D-s2, d0 DIN EN 14374
or according to
approval
200/70 From DIN
EN 13986
0.09–0.17,
depending on
bulk density
180 -350.9
58 Polymeric diphenyl-
methane diisocyanate
(PMDI)
600–700 D-s2, d0 According to
approval
50/15 0.13 268.83 -768
42.1 Phenol-formaldehyde
(PF) or melamine-urea-
formaldehyde (MUF)
resin or polymeric di-
phenylmethane diisocy-
anate (PMDI)
550–650 D-s2, d0 Depends on applica-
tion and thickness,
as per DIN EN 300
depending on board
types 1–4, main axes
14–30, minor axes
7–16
50/30 From
DIN EN 13986
0.13
265.43 -565
58 Urea-formaldehyde (UF),
phenol-formaldehyde
(PF) or melamine-urea-
formaldehyde (MUF)
resin or polymeric di-
phenylmethane diisocy-
anate (PMDI), paraffin
sometimes added
DIN EN 13986
300–900
D-s2, d0
D-s2, d2
5.8–18.3 from
DIN EN 12369-1
depending on appli-
cation and thickness
acc. to DIN EN 312
50/10-20 From
DIN EN 13986
0.07–0.18,
depending on
bulk density
268.83 -768
862 Portland cement, foamed
clay granulate, foamed
glass granulate, alkali-
resistant glass fibre mesh
1,000–1,500 B-s1, d0 9 (for all thicknesses)
from DIN EN 634-2
50/30 From
DIN EN 13986
0.23
298.75 357
100.3 Urea-formaldehyde
(UF) or melamine-urea-
formaldehyde (MUF)
resin, phenol-formalde-
hyde (PF) or polymeric
diphenylmethane diiso-
cyanate (PMDI)
760–790 E to
D-s2, d0
5.1–20
from DIN EN 622-5
depending on the
application and
thickness range
30/20 From
DIN EN 13986
0.08–0.14,
depending on
bulk density7)
295.3 -668.6
1.5 Natural tree resin, alum
or hydrophobic materials
such as bitumen, paraffin,
latex or polyurethane
(PUR), fire retardants
may be added
40–2305)
E 0.8–1.3
from DIN EN 622-4
depending on the
application and
thickness range
5/3 0.039–0.0457)
88.55)
-164
54 Portland cement or
magnesite-bonded
350–570 A2 – s1,
d0 to B-s1,
d0
depending on the
application and
thickness range,
DIN EN 13168
5/3 0.08–0.116)
133.746)
136.3
5)
dataholz.com – catalogue of structural ecologically certified timber structural components, partly converted
6)
Manufacturer EPD; partly converted
7)
Informationsdienst Holz, Faserdämmstoffe (fibre insulating materials)
Source: Rüter, Sebastian; Diederichs, Stefan: Ökobilanz-Basisdaten für Bauprodukte aus Holz. Arbeitsbericht aus dem Institut für Holztechnologie, No. 2012/1;
Published by Johann Heinrich von Thünen-Institut. Hamburg 2012

24. 24
Life-cycle assessment
Annette Hafner, Holger König
The construction sector is responsible for
a large proportion of our consumption of
resources as well as for our greenhouse gas
emissions, with the construction of buildings
consuming around 40% of all of energy and
materials. This sector also produces 36% of all
greenhouse gases and 33% of all waste. [1]
This creates a need for planners to increasingly
focus on environmental aspects in designing
and planning buildings. Using buildings in
more energy-efficient ways will not be enough
to achieve the targets for reducing greenhouse
gas emissions, so the choice of building mater-
ials will play an increasingly important role in
reaching these targets. More use of wood and
wood-based materials could contribute signifi-
cantly towards reducing the construction sec-
tor’s carbon (CO2
) emissions in the long term.
The amount of CO2
in the atmosphere can be
reduced in two ways: either by reducing CO2
emissions or by extracting CO2
from the atmos-
phere and storing the carbon. Wood has the
unique ability to contribute to both of these
possible reduction methods.
Life-cycle assessments (LCAs) are an estab-
lished method of quantifying a product’s environ-
mental impact and make it possible to compare
the environmental impacts of different products
and the environmental parameters of buildings
built in different ways. The information they yield
is key in demonstrating wood’s positive effects
on the climate and can be used to help make
decisions for or against using this material.
A life-cycle assessment of a building consists
of two parts: firstly, a materials flow and energy
balance plus verification of the resources
(including lists of materials) and renewable
and non-renewable primary energy used, and
secondly, an impact assessment based on
various indicators such as greenhouse gas
emissions for energetic use, ozone depletion
and the potential for summer smog, acidifica-
tion and eutrophication. Based on this data,
the proportion of renewable raw materials
in the building product is ascertained and
the amount of carbon (C) stored and thus
the extent to which the materials temporarily
sequester CO2
is calculated. Impact assess-
ments can be drawn up by linking the mass
of the building products used with data from
the life-cycle assessment. System boundaries,
functional equivalents and the data sources
on construction products included in the calcu-
lations are highly relevant in calculating and
comparing the entire life-cycle assessment of
buildings. DIN EN 15978 (Assessment of the
environmental performance of buildings) and,
at the product level, DIN EN 15804 (Environ-
mental product declarations) now provide a
consistent basis for evaluating building life-
cycle assessments. The standards offer clear
rules for adequately representing the special
features of timber construction. The most up-
to-date data sets for timber construction prod-
ucts and building with wood are available from
the Thünen Institute of Wood Research [2].
The impact of global warming potential (GWP)
is also often referred to as an ecological or
carbon “footprint”. It measures the anthropo-
genic proportion of global warming and is
specified as a CO2
-equivalent. To ensure that
calculations include the retention period of
greenhouse gases in the atmosphere, a carbon
footprint always includes an integration period,
usually GWP 100, a period of 100 years. Accur-
ate statements on the amount of CO2
stored
through the use of renewable building materials
in a building during its use stage cannot be
made based on the indicator of greenhouse
emissions alone, because the carbon seques-
tered by the materials is burnt at the end of its
life cycle so the sequestration effect is lost.
Timber buildings can contribute to environ-
mental protection
Timber components in buildings store carbon
and delay its release until the component is dis-
posed of. However, carbon is released during
disposal if the wood is burnt to generate energy.
The longer timber is used as a material, the
longer this storage effect is maintained, so a
timber building temporarily sequesters carbon.
Carbon sequestration can play an important
role in improving the effectiveness of forests
in reducing CO2
levels. In the 1997 Kyoto
Protocol the delayed emissions from timber
products that sequester carbon were not
taken into account in the first commitment
period’s inventory rules. After negotiations at
the Durban Climate Change Conference in
2011, the agreements reached under the Kyoto
Protocol were extended and some of the rules
on the inventory and quantifying of the forestry
and timber industry were amended. Since then,
the reporting and inclusion of forestry manage-
ment has been introduced as obligatory and
any temporary, dynamic changes in the car-
bon pool of wood harvested and used must
be explicitly taken into account [3]. Under
the Kyoto Protocol and agreements reached
at the Durban Climate Change Conference,
from early 2013 the use of wood products as
material was credited in the second commit-
ment period until 2020, although the credits
were provided only at the national level and
only for domestic timber. Every increase in
the use of wood as a material and especially
for more use of domestic timbers in construc-
tion has a positive effect on the CO2
balance.
Germany identifies this effect based on a
set reference (reference level for forestry
management) at the end of the commitment
period. Quantifying the expected impact of
an increased use of wood as a material on
the climate is also very important at a national
level and can help to enhance the sink effect
of forests. The amount of carbon in the wood
used is estimated based on amounts of sawn
timber and wood-based materials used and
on paper consumption. Wood used in the con-
struction sector is comprehensively considered
in this survey [4].
A 4.1 Passive house, Samer Mösl housing estate,
Salzburg (AT) 2006, sps-architekten
A 4.2 Amount of carbon (C) and its conversion into
CO2
-equivalent shown for examples of specific
buildings

25. 25
Holztechnikum Kuchl college
Samer Mösl housing estate
Ludesch community centre
Garmisch-Partenkirchen tax office
Lebenshilfe workshops, Lindenberg
New replacement building, Fernpaß-
straße housing development, Munich
Modernising of Fernpaßstraße
housing development, Munich
Modernising of Grüntenstraße
housing development, Augsburg
Modernising of Gundelfingen
primary school
0 200 400 600 800 1000 1200 1400
Absolute figures for carbon and CO2 sequestration in building [t C/CO2]
Housing in Erlangen
Munich-Hadern youth centre
CO2
C
A 4.2
A 4.1
Life-cycle assessment
To demonstrate the effects of the climate
neutrality of wood that is taken as a basis
in assessing the CO2
balance of forests,
only wood from domestic forests is taken into
account as contributing to timber products’
carbon sequestration. Article 3.4 of the Kyoto
Protocol requires that it be inventoried in
advance. This means that wood harvested
from logging is excluded from this balance.
For this reason, certification systems for build-
ings in Germany require proof that the wood
used has a FSC (Forest Stewardship Council)
or PEFC (Programme for the Endorsement of
Forest Certification Schemes) certificate. How-
ever, these certificates do not provide any
information as to whether the sustainability
of forests and CO2
neutrality of the timber is
ensured in each nation.
To assess the impact of timber buildings on the
environment, the carbon they sequester must
be separately recorded in groups of materials.
Substitution factors for buildings can also be
determined if they are built with timber instead
of mineral building materials. Life-cycle assess-
ments make it possible to develop these deter-
minations.
Carbon sequestration and substitution
Two aspects are of particular interest in
assessing the impact on the environment of
wood and timber products in construction:
• The carbon sequestered by the building
• The substitution of finite raw materials
Renewable raw materials and carbon sequestration
CO2
balancing of forestry management was
included in the amended Kyoto Protocol rules
for the second commitment period. This cre-
ates a basis for including the effects of the
carbon sequestration of wood products in
determining a building’s environmental impact.
For this reason, the amount of carbon tied into
a building is verified and offset in the produc-
tion stage (with a minus symbol) in a life-cycle
assessment. When the building or parts of it
are disposed of, the carbon is released and
the greenhouse gas emissions for inciner-
ation are calculated, so the negative offset in
production and calculation of greenhouse
gas emissions from disposal compensate each
other, which is often somewhat simplistically
referred to as the “climate neutrality” of renew-
able raw materials. The Intergovernmental
Panel on Climate Change (IPCC) has published
lists of the quantities of carbon stored in vari-
ous timber products. It is assumed that there is
225 kg of carbon in each m3
of timber (that has
a bulk density of 450 kg and is absolutely dry).
DIN EN 16449 prescribes the conversion of
stored carbon into CO2
.
Based on this approach to the balance, the
carbon sequestration effects of various mater-
ial-specific structures in the building sector
can be determined, calculated, assessed and
compared. Figure A 4.2 shows examples of
different buildings and their absolute amounts
of carbon resulting from the use of products
made of renewable raw materials in buildings
and their conversion into carbon dioxide in
tons [5].
Potential savings from substitution
As well as temporarily storing biogenic carbon,
construction products made of renewable
materials can replace or substitute compo-
nents made of finite resources such as plastics,
metals and minerals. A fundamental precondi-
tion for estimating the potential savings result-
ing from the use of construction products made
of renewable materials is the application of the
same functional equivalents. This precondition
is fulfilled by surveys of each cubic metre of
a particular structural element or of the same
part of the building with the same energy con-
sumption. Substitution potential varies for each
environmental indicator. The potential for the
indicator “greenhouse gas” (CO2
-equivalent
or CO2
-eq.) is shown as an example here.
The substitution effect that can be achieved
by using products made of renewable raw
materials can vary greatly depending on the
choice of materials used in the primary struc-
ture and for fittings (windows/ doors, floors
and facade cladding). The literature on this
topic usually currently draws on the meta-
study by Sathre & O’Connor, which identified
an average substitution factor of 3.9 t CO2
-eq.
per tonne of timber used [6]. However, these
figures do not take current standards into
account and contain possible credits. On-
going research projects show that these factors
have to be reviewed and recalculated [7]. The
figure for wood can be estimated at between
1.6 and 2.6 kg CO2
-eq. of fossil-derived green-
house gas emissions per kilogram of timber
used in an average detached house. Depend-
ing on the part of the building to be substituted
pursuant to DIN EN 15978, it includes Modules
A and C for the primary structure and fittings,
but not the credits from the extra benefits in
Module D. These can be accounted for separ-
ately [8].
Carbon sequestration versus an efficient
use of resources in construction
If extensive carbon sequestration contributes
to the achieving of climate protection goals, it
would seem to be advisable to use wood as a
building material wherever possible. Yet if we
want to use material resources efficiently and
timber structures appropriately, we should not
necessarily leap to this conclusion too quickly.
Efforts to use more wood as a material, espe-
cially in competition with the use of wood to
generate energy, must be balanced to ensure
that enough renewable raw materials remain
available. The potential effects of extensive
carbon sequestration and the efficient use of

26. 26
43
91 96
119
128
118
136
98
141
189 186
170
204
163
188
0
50
100
150
200
250
EW: TFC EW: TFC,
solid wood
EW: TFC
GF + 4 FS GF + 4/6 FS GF + 5 FS
CS: Stb
Wooden
floorboards
CS: Wood-
concrete
composite
CS: Wood-
concrete
composite
CS: Wood-
concrete
composite
RS: SRC
Wooden
floorboards RS: Solid wood RS: Timber
beams
IW: SRC
IW: SRC (GF)
Solid wood (UF)
IW: SRC and
Timber studs
EW: TFC
GF + 3 FS
CS: Timber
beams
RS: Timber
beams
IW: Timber
studs
EW: TFC
GF + 3 FS
(Var. 1)
RS: Timber
I beams
IW: Timber
studs
CS: Timber
beams
CS: Timber
beams
EW: TFC
GF + 3 FS
(Var. 2)
RS: Timber
I beams
IW: Timber
studs
CS: Solid
wood
EW: TFC
EGF + 3 FS
(Var. 3)
RS: Timber
I beams
IW: Timber
studs
CS: Timber
I beams
EW: TFC
GF + 3 FS
(Var. 4)
RS: Timber
I beams
IW: Timber
studs
EW: TFC
GF + 3 FS
(Var. 5)
RS: Timber
beams
IW: Solid
wood
CS: Solid
wood
EW: TFC
GF + 2 FS
RS: Solid
wood
IW: Timber
studs, SRC
CS: Solid
wood
EW: TFC
GF + 7 FS
RS: Solid
wood
IW: Solid
wood
CS: Solid
wood
EW: Solid wood
GF + 7 FS
(Var. 1)
RS: Solid
wood
IW: Solid
wood
CS: Solid
wood
EW: TFC/
Solid wood
GF + 5 FS
RS: Timber
I beams
IW: Solid
wood
CS: Solid
wood
EW: TFC
GF + 3 FS
RS: Solid
wood
IW: Solid
wood
CS: Solid
wood
EW: Solid
wood
GF + 3 FS
RS: Timber
I beams
IW: Timber
studs
SC: SRC and
steel
SC: SRC and
steel SC: SRC SC: SRC SC: SRC
SC: SRC SC: SRC SC: SRC SC: SRC SC: SRC SC: SRC SC: SRC SC: SRC SC: SRC SC: Steel
Renewable
raw
materials
[kg/m
2
WF]
Hybrid Timber construction
A 4.3
Life-cycle assessment
wood as a resource and a material should be
considered individually for each building task.
Optimising buildings in terms of structural,
fire safety, energy use, economic and interior
climatic criteria will always involve compromise
and every type of construction will result in a
different optimum. Buildings’ support structures
require large quantities of materials to build
them, so they can extensively sequester car-
bon. Facades, on the other hand, need to be
well insulated and as thin as possible, so the
large quantities of insulating materials they
require mean that less timber is used in their
construction and less carbon is stored in that
way. Visible interior walls and solid timber
ceilings offer potential for extensive carbon
sequestration, but it may be preferable for
soundproofing or fire safety reasons to build
these structures in other ways. Individual areas
must be considered in each case.
A German Federal Environmental Foundation
(Deutsche Bundesstiftung Umwelt – DBU)
research project compared various timber
buildings with each other and analysed the
differences in amounts of renewable raw
materials used in buildings and their carbon
sequestration and greenhouse gas emissions
[9]. Fig. A 4.3 shows the amounts of renewable
raw materials in timber apartment buildings,
which are classified as hybrid buildings (with
a certain proportion of timber in exterior walls),
timber-frame structures or solid timber struc-
tures (with cross laminated timber load-bearing
structures). Related superstructures and fittings
are also shown.
Appropriate government funding and support
programmes are also important in helping
to establish timber construction. The City of
Munich, for example, has a funding programme
that supports the construction of environmen-
tally-friendly timber buildings and pays a sub-
sidy for every kilogram of carbon stored under
certain conditions, as long as timber from sus-
tainable forestry is used.
CO2
-efficient timber construction
If construction is to be as CO2
-efficient as
possible, contractors and clients must take
decisions to pursue this type of construc-
tion and set precise goals at the outset of
planning.
Planning CO2
-efficient buildings
Target values based on the following assump-
tions should be set in the preliminary design
phase:
• Use of timber in the primary support struc-
ture, which has a major influence on the
results of the life-cycle assessment.
• Keeping energy consumption to a minimum
during the use stage.
• The fixing of maintenance cycles for individ-
ual structural components. They influence
construction and create specifications for
construction quality.
• Formulation of disposal scenarios for the
entire structure and for any dismantling into
individual parts with options for reusing
timber elements.
The connection between the construction and use
stages
Efforts to optimise buildings have so far con-
centrated on the lowest possible energy con-
sumption and keeping CO2
emissions low
during the use stage. With the introduction
of the passive house standard, almost-zero
energy and plus-energy buildings, there is an
increasing focus on the potential savings that
the construction and maintenance of buildings
can offer.
Figure A 4.4 shows a comparison of the pri-
mary energy requirements of a multi-storey
building according to the EnEV 2009 standard
(70 kWh/m2
a) and those built to a passive
house standard (15 kWh/m2
a), with the energy
required for construction, maintenance and
energy supply shown for a period of 50 years.
It clearly demonstrates that the overall energy
consumption of buildings with highly effi-
cient energy standards is lower over the
building’s life cycle. At the same time, the
percentage distribution between buildings
(construction) and energy supply shifts in
the use stage, so primary energy consump-
tion assumes vital importance in buildings
with high energy consumption standards.
More than 50% of primary energy requirements
and greenhouse gas emissions generated
by passive house buildings are produced by
the building’s construction and maintenance,
so there is an increasing focus on the overall
material concept and on individual construction
products. The better a building’s energy use
standard is and the less energy it consumes,
the more influence its construction will have on
its overall life-cycle assessment.
Dismantling and disposal
The EU’s Waste Framework Directive estab-
lishes a waste hierarchy and prescribes that,
in Europe, as much material as possible
should be re-used or recycled [10]. In a sec-
ond step, material is also regarded as an
energy resource. If wood is to be reused as
a material, it must be classified as waste
wood [11]. Only timber that is not contamin-
ated with hazardous substances can be
reused, so timber that has been treated with
chemical timber preservatives cannot be re-
used, but must be used to generate energy.
Better reuse of untreated, reclaimed timber
can help to stabilise the amounts of timber
available at a reasonable cost in the long
term. Solid wood should generally be first
used as construction timber, with the next
step being the use of weak wood and wood
cut during thinning in wood-based materials.
The third and last option is to use wood in
thermal energy recovery. This approach
greatly extends and expands the extent of
carbon sequestration.

27. 27
Construction
Maintenance
Building services
over 50 years
25%
Apartment building EnEV 2009 standard
(70 kWh/m2
a)
Apartment building Passive house standard
(15 kWh/m2
a)
6%
36%
17%
47%
69%
A 4.4
Life-cycle assessment
Long transport routes have a negative
effect on environmental assessments and
the fossil fuels used to achieve them reduce
primary energy efficiency, so the wood for
buildings should be sourced from the region
in which it is processed and used and then
reused in thermal energy recovery as far as
possible.
Cascading use of raw materials
A targeted extension of the material life cycle
of solid wood products and the consistent
application of “cascading use” (multiple reuse
of a raw material) can open up sources of raw
materials for new products. Keeping contami-
nants to a minimum and intelligent dismantling
concepts (reuse or recycling of valuable mater-
ials) can make it possible to greatly reduce
the amounts of raw materials used in thermal
energy recovery. In the wood-processing sec-
tor, the potential of efficient cascading use is
only fully exploited in horizontal reprocessing
and recovery (e.g. simultaneous use of wood,
bark and shavings) and remains otherwise
largely unused. Vertical integration of this kind
of use over the whole life cycle of materials
could be expanded. Every structure is built in
layers. The layers and their sequences are
closely connected with the total service life of
the structural element and must be designed
and optimised with maintenance, dismantling
and recycling scenarios during the planning
stage. When the interaction of layers is well
planned, structural elements and components
can be better demarcated from each other
and joints designed with a view to subsequent
dismantling, with a focus on detachable con-
nections in structures (e.g. screws instead of
adhesives).
The carbon footprint of timber in buildings
Some general guidelines must be considered
when using timber to sequester carbon in
buildings:
• To build carbon-efficient buildings, specifi-
cations on the structure’s carbon footprint,
primary energy consumption (in the form
of material and energy) and the amount of
renewable raw materials used in it must be
established in the planning phase.
• The intensive energy use of mineral building
materials means that parts of buildings such
as cellars and foundations have a major
impact on buildings’ carbon footprints. The
extent of the effect will depend on the size
of cellar and type of foundation. The taller a
building is, the lower their percentage ratio
will be.
• The wood used must come from sustainable
forestry management.
• The extent of carbon sequestration increases
with the amount of wood or wood-based
materials used. Support structures require
large amounts of materials. Another factor
that may increase carbon sequestration is
the use of planar solid wood structural com-
ponents in walls, ceilings and roofs.
• The amount of timber used must be consid-
ered in relation to a resource-saving use of
timber stocks, so the advantages of max-
imum carbon sequestration must be weighed
up against an economical use of timber.
• Local government authorities should estab-
lish sustainable contract award practices
by prescribing maximum carbon footprint
specifications for the construction phases of
different types of buildings. These could be
anchored in development plans.
Comparative evaluations of conventional
and timber buildings based on life-cycle
assessments
Comparisons made between buildings built
using conventional (mineral) materials and
methods involving construction products made
of finite resources and buildings containing
high proportions of products made of renew-
able raw materials reveal the significant
potential environmental benefits that timber
buildings can offer the ecosystem. One
example of this are the comparative life-cycle
assessments published in the catalogue for
the “Bauen mit Holz – Wege in die Zukunft”
(“Building with wood – paths into the future”)
exhibition [12], that analyse eight examples
of buildings in which many structural compo-
nents made of renewable raw materials were
used. The life-cycle assessments carried
out make use of the ÖKOBAUDAT database
(oekobaudat.de; 2011–2013 version) as basic
information. LEGEP software was used to
model and calculate objects. Each building
was compared with a model of a standard ver-
sion with conventional construction products
made largely of non-renewable, i.e. mineral,
metallic and synthetic raw materials. This ver-
sion was identical with the actual building in
its space, area and design and met the same
energy targets. The structural components
were taken from the LEGEP database element
catalogue and had the same structure and
choice of materials as those built into many
buildings already assessed. The modelling
of these “non-identical twins” clearly shows
the difference between various construction
methods.
In the following life-cycle assessments, the
buildings were surveyed from the lower edge
of their ground floor slabs. Cellars and founda-
tion elements (with cellars under some or all
of the floor space and foundations) were not
included in the assessments because they
would have tended to distort the results in
terms of the building’s function and its mater-
ial quality.
Only buildings with timber primary support
structures were taken into account. The vari-
ous building materials were grouped into
non-renewable (mineral, metallic, synthetic)
and renewable raw materials (wood, plant and
A 4.3 Amounts of renewable raw materials in kg/m2
of
living space for various timber and hybrid apart-
ment blocks
Ground floor (GF), upper floor (UF), full storeys
(FS), exterior walls (EW), timber frame construc-
tion (TFC), ceiling structure (CS), steel-reinforced
concrete (SRC), inner walls (IW), roof structure
(RS), staircase (SC)
A 4.4 Correlation between primary energy consumption
used to build buildings with different energy use
standards and their primary energy consumption
over 50 years

28. 28
Life-cycle assessment
animal fibres) for the purposes of evaluation.
To facilitate comparisons of objects, the refer-
ence value was 1 m2
of gross floor area only
above ground, and the kilogram was used as a
unit of weight.
The comparison shows that buildings made of
renewable raw materials had about 50–65% the
weight of conventional buildings. The results
also showed a very low proportion of renew-
able raw materials of just 0.5–1% of the total
weight of conventional buildings. In buildings
containing high proportions of renewable raw
materials, they accounted for up to 18% of the
total weight. The low percentage of their share
of the weight – despite an almost exclusive use
of wood – was due to the heavy weight of the
mineral building materials used. A concrete
floor slab in a timber building weighs about
as much as two timber slabs plus the flooring.
Most of the buildings surveyed had two stor-
eys. The influence of a mineral floor slab only
decreases significantly in multi-storey timber
buildings.
Figure A 4.5 shows the results of such a com-
parison of buildings, based on the example
of the Fernpaßstraße housing development in
Munich [13].
The results of this study will have to be recalcu-
lated to take into account the current DIN EN
15978 standard and adjusted ÖKOBAUDAT
from 2015. Credits (Module D) for the inciner-
ation of building products at the end of their life
cycles to generate energy will no longer be
included in the calculations, so that the advan-
tageousness of the global warming potential
indicator levels off at up to 50% [14].
Conclusion
The construction sector offers considerable
opportunities for greatly reducing greenhouse
gas emissions. New buildings are always
more energy-efficient to operate, so interest
in the carbon footprint of building materials is
increasing.
The advantages of using timber from an ecological
point of view
Timber products offer a number of significant
advantages from a climate protection point of
view:
• Wood used as a construction product can
have a double climate protection advantage.
Compared with other building materials, it
produces only low CO2
emissions from fossil
sources and it can store CO2
and remove it
temporarily from the atmosphere.
• The best ways to take advantage of the
potential savings of CO2
that wood offers for
the building sector are to use a high propor-
tion of timber products, to use wood prod-
ucts that are as durable as possible, and to
replace energy-intensive materials with wood
and wood-based products.
• Specific national factors significantly influ-
ence the carbon footprint of construction
products and buildings, because the differ-
ent energy sources in the electricity mix
of various countries can mean that simi-
lar production processes may have differ-
ent carbon footprints. These factors must
be properly considered when assessing
products.
• To avoid negative effects on the carbon
sink effect of forests, wood must come from
sustainably managed forests.
• Wood and wood-based building materials
can be reused, recycled as a material and
then be used to generate energy in cascad-
ing use, which can extend the period for
which atmospheric carbon is stored many
times over. A cascading use of wood not only
makes it possible to use this resource effi-
ciently, it also allows for multiple substitution
effects due to the use of more energy-inten-
sive materials and/or of fossil energy sources
in energy recovery.
The carbon footprint of structural components in
timber buildings
Building with timber, which can temporarily
sequester carbon and replace non-renewable
materials, can make a major contribution to
achieving climate protection goals, as long
as the wood comes from sustainable forestry.
The following factors should also be taken
into account:
• Foundations and cellars have the biggest
influence on the carbon footprints of build-
ings. The extent of their influence depends
on the size of cellar and type of foundation.
The taller the building, the lower the ratio of
their influence will be.
• The extent of carbon sequestration increases
with the amount of timber from sustainable
forestry used in a building.
• Most of the carbon in a building is stored
in its support structure because it requires
the largest amount of timber. Solid wood
structures use a great deal of timber so they
store a large quantity of carbon. The amount
of timber used must, however, be propor-
tionate to the use of timber in a way that
preserves it as a resource, so the advan-
tages of maximum carbon sequestration
must always be weighed up against an eco-
nomic use of timber.
• A building’s fittings (floor coverings, win-
dows, doors and any wooden facade clad-
ding), regardless of the material used for
the support structure, can influence carbon
sequestration in the long term, particularly
since fittings may be replaced several times
over a building’s life cycle [15].
• The carbon footprint of assembly on a build-
ing site is minor compared with that resulting
from the manufacture of building materials.
• Maintenance of structural components
(e.g. by providing the wood with structural
protection) is essential for optimising the
durability of building products beyond
the building’s life cycle and thus its carbon
footprint.
A 4.5 Comparison of selected indicators in life-cycle
assessments (calculated with ÖKOBAUDAT
2011–2013) made between timber buildings
in the Fernpaßstraße housing development
in Munich (DE) 2012, (Architekten Hermann
Kaufmann/Lichtblau Architekten) and buildings
built with conventional materials. Period under
review – 50 years
A 4.6 Fernpaßstraße housing development

29. 29
Timber
Standard
Timber – Primary energy non-renewable – Primary energy renewable of which proportion of heating value
Standard – Primary energy non-renewable – Primary energy renewable of which proportion of heating value
Timber – non-renewable – renewable
Standard – non-renewable – renewable
Timber
Standard
0 5 10 15 20
0 0.04
0.02 0.06 0.08 0.1
0 500 1000 1500
0 30
10 20 40 50 60
Comparison of greenhouse potential [in kg CO2
-equivalent to each m2
of net floor space and year]
Comparison of abiotic resource potential [in kg of antimony-equivalent to each m2
of net floor space and year]
Comparison of primary energy consumption for construction, maintenance and disposal
[in kWh for each m2
of net floor space and year]
Comparison of material required for construction and maintenance [in kg per m2
of gross floor area]
A 4.5
A 4.6
Life-cycle assessment
Notes:
[1] COM (2007) 860 final: A lead market initiative for
Europe. http://eur-lex.europa.eu/LexUriServ/
LexUriServ.do?uri=COM:2007:0860:FIN:en:PDF.
20.07.2015
[2] Basic data timber balance for timber construction
products. http://www.holzundklima.de/projekte/
oekobilanzen-holz/docs/Rueter-Diederichs_2012_
OekoHolzBauDat.pdf. 23.11.2015
[3] Reporting under the United Nations Convention on
Climate Change and Kyoto Protocol 2012 – National
inventory report on the German greenhouse gas in-
ventory (Nationaler Inventarbericht zum Deutschen
Treibhausgasinventar) 1990–2010. Published by the
Umweltbundesamt (German Environment Agency),
08/2012
[4] Rüter, Sebastian: Projection of Net Emissions from
Harvested Wood Products in European Countries –
For the period 2013–2020. Working report from
the Institut für Holztechnologie und Holzbiologie
No. 2015/1, Johann Heinrich von Thünen Institute
(vTI), p. 63. http://literatur.thuenen.de/digbib_
extern/dn048901.pdf. 24.02.2017
[5] Kaufmann, Hermann; Nerdinger, Winfried et al.:
Bauen mit Holz: Wege in die Zukunft. Munich, 2011
[6] Sathre, Roger, and O’Connor, Jennifer. Meta-analysis
of greenhouse gas displacement factors of wood
product substitution. In “Environmental science &
policy” 13, 2010, p. 104–114
[7] THG-Holzbau: Treibhausgasbilanzierung von
Holzgebäuden – Umsetzung neuer Anforderungen
an Ökobilanzen und Ermittlung empirischer Substitu-
tionsfaktoren. Joint project of the RUB, Thünen Insti-
tute, TUM and Ascona GbR. Final report scheduled
for publication in 2017
[8] Current calculations in the THG-Holzbau research
project were carried out for this purpose.
[9] Methodenentwicklung zur Beschreibung von Ziel-
werten zum Primärenergieaufwand und CO2
-Äquiv-
alent von Baukonstruktionen zur Verknüpfung mit
Grundstücksvergaben und Qualitätssicherung bis
zur Entwurfsplanung. German Federal Environmental
Foundation (Deutsche Bundesstiftung Umwelt), File
number 31943/01
[10] DIRECTIVE 2008/98/EC. http://eur-lex.europa.eu/
legal-content/EN/TXT/?uri=URISERV:ev0010.
10.08.2015
[11] In Germany this is done through the Altholzverord-
nung, AltholzV (Waste Wood Ordinance) , 2012
[12] König, Holger: Ökobilanz-Vergleich von Gebäuden
in Holzbauweise im Vergleich zu Standard-Bauwei-
sen bei Neubauten und bei Gebäudemodernisie-
rung. In: Kaufmann, Hermann; Nerdinger, Winfried
(eds.): Bauen mit Holz – Wege in die Zukunft. Sup-
plement to the exhibition catalogue of the same
name. Munich, 2015
[13] ibid.
[14] as for Note 7
[15] ibid.

30. 30
A 5.1
Interior air quality –
the influence of timber
construction
Maren Kohaus, Holger König
Wood has been used as a construction mater-
ial for human habitations for centuries and
wood and wood-based materials are still used
in a wide range of ways as a construction
material, flooring, wall and ceiling cladding
and to make fittings and furnishings in modern
buildings.
The material is highly prized for its naturalness
and authenticity. Wood surfaces in particular,
due to the material’s specific character, colour,
grain, texture and porousness, are generally
regarded as appealing to your senses, as
various investigations by Maximilian Moser
and the “Interaktion Mensch und Holz” study
confirm [1]. Wood’s specific structural and
physical characteristics such as low thermal
conductivity (-value = 0.11–0.17 W/mK) and
low thermal effusivity coefficient or b-value
(Fig. A 5.3) mean that wood surfaces are usu-
ally perceived as warm. Natural wood sur-
faces also help to regulate interior climates
because wood absorbs moisture from the
interior air and gradually releases it again [2].
The smell of wood, which is made up of emis-
sions of volatile substances, has a pleasantly
calming effect on some people. A 2003 study
by the Joanneum Research Forschungsge-
sellschaft on the potential effects of stone
pine wood in the immediate environment on
people’s circulation and sleep found that it
improved their performance and general well-
being [3].
Maximilian Moser’s 2007 “Schule ohne Stress”
(School without stress) study analysed the
effect of solid wood fittings and equipment
in classrooms. It came to the conclusion that
the calming effect of wood, estimated by
measuring the students’ heart rates and vagal
tone, could have a positive effect on health [4].
Current research projects, such as the HOMERA
study, are seeking to establish findings on the
possible effects of wood and wood products on
health by means of technical scientific observa-
tion and medical evaluation [5]. Given the com-
plexity of the topic, the potential of research in
this area is immense.
Until further findings become available, discus-
sions on the extent to which emissions from
wood and wood-based materials in contempor-
ary timber buildings can be regarded as harm-
ful to health, as inherent to wood and therefore
natural and harmless, or even promote health,
will remain current. To offer clients, users and
planners some security and bring some clarity
into the discussion, relevant aspects will be
examined in detail below.
A healthy indoor climate
Regardless of how a building is built, it must
provide an indoor climate that users perceive
as pleasant and accommodate activities for
which rooms are designated. Comfort criteria
(as specified in DIN EN 15251) offer guidance
on the factors that need to be taken into
account:
• Protection from cold, heat and moisture/
damp caused by weather
• Protection from high levels of moisture
caused by usage and resulting condensation
and mould formation
• Protection from interior and exterior noise
pollution
• Optimum lighting and adequate daylight as
well as protection from excessive sunlight
(heat/overheating)
• Sufficient ventilation for the particular usage
and a resulting reduction in CO2
concen-
trations
• Protection from ionising (e.g. radon) and
non-ionising radiation (e.g. electric smog)
• Low-level pollution of interior air from building
materials, equipment and devices
An adequate exchange of air provided by
manual or mechanical ventilation ensures that
emissions produced by building products,
electronic devices and by people are dissi-
pated, although toxin-free building materials
should be used where possible.
Emissions in interior air
Materials used inside buildings can pollute the
air within by emitting particles in the form of
dust, fibres or gases. Relevant for interiors are
only those emissions that are released within
the airtight layer (see “Airtight layers”, p. 97f.).
A 5.1 Interior wood in a kindergarten, Bizau (AT) 2009,
Bernardo Bader Architekten
A 5.2 Recommended TVOC levels and resulting recom-
mended action(s)
A 5.3 Thermal effusivity coefficients of certain building
materials
A 5.4 Classification of chemical compounds by boiling
point