hout, nieuwbouw, Nederland, houtgebruik Universiteit van Amsterdam PhD Fraanje PJ

1. Originalarbeiten á Originals Holz als Roh- und Werkstoff 57 (1999) 407±417 Ó Springer-Verlag 1999
Use of wood in new Dutch one family dwellings since 1969
P. J. Fraanje
407
The application of wood for building purposes, especially È È
Holzverwendung fur neue hollandische
when used in constructions, can be seen as a high quality È
Einfamilienhauser seit 1969
application. As wood is, in contrast with most other Die Verwendung des Rohstoffs Holz im Bauwesen, vor al-
building materials, a renewable resource, and because the È
lem fur Holzkonstruktionen, kann man als Nutzung von
environmental impact is relatively low, wood is promoted È
hoher Qualitat ansehen. Holz ist im Gegensatz zu den
by the Dutch government in the ``20% more wood for the meisten anderen Baumaterialien ein erneuerbarer Rohstoff.
building sector'' programme. In this article an overview is Weil die Belastung der Umwelt relativ niedrig ist, wird die
given of wood utilization in new one family dwellings È
Holzverwendung durch die niederlandische Regierung im
(OFD's), built in the past three decades. The wood use per Rahmen des Programms ,,20% mehr Holz im Bau`` gefor- È
average OFD dropped from 6.2 m3 in 1969 to 3.4 m3 in È
dert. In diesem Beitrag wird die Holzverwendung fur neue
1996. Most of the wood is currently applied to roof and È
Einfamilienhauser (EFH) in den letzten dreiûig Jahren
window frames. It appears that there is a decrease in the analysiert. Fur ein EFH brauchte man im Jahre 1969 6,2 m3
È
total wood use for new OFD's and that the amount of wood Holz, 1996 dagegen nur 3,4 m3. Heute sind Dach und
products per average OFD also shows a declining ten- È
Fenster die wichtigsten Bauteile fur die Holzverwendung.
dency, counterbalanced however by a growing gross ¯oor Es zeigt sich, daû sowohl die gesamte Holzverwendung als
area and an increasing number of unsubsidized OFD's. For auch die durchschnittliche pro EFH laufend sinkt, obwohl
1996, a balance of the total amount of wood applied in all È
die Brutto-Boden¯ache der EFH gestiegen ist. Dies liegt
OFD's with the input and output of wood products is daran, daû der Anteil nicht subventionierter EFH in den
presented. The total wood stock in all OFD's is estimated È
letzten Jahren zunahm. Fur 1996 wird hier eine Bilanz der
to amount 21 ´ 106 tonnes for 1996. This can be seen as a È
gesamten Holzmenge fur alle EFH zusammen mit In- und
reservoir out of which wood becomes available every year È
Output von Holzprodukten prasentiert. Die gesamte
through renovation and demolition of OFD's. This sec- Holzmenge in EFH betragt rund 21 ´ 106 t und steht jedes
È
ondary wood (together with wood waste from newly built È
Jahr fur Abbruch und Renovierung von EFH bereit. Das
OFD's) can be cascaded, so that the resource wood is È
Altholz kann (zusammen mit Holzabfallen von Neubauten)
optimally used. The article concludes with options to in- wieder verwendet werden (cascade), so daû der Rohstoff
crease the amount of wood used in new OFD's, by ± È
Holz optimal genutzt wird. Eine Moglichkeit zur Steigerung
amongst others ± increasing the market shares of timber È È
der Holzverwendung fur EFH bietet z.B. die Erhohung des
frame dwellings, wooden ¯ooring and wooden foundation È È
Marktanteils im Holzskelettbau, bei holzernen Fuûboden
piles. und Fundamentierungspfahlen.È
1
Introduction
The use of timber in dwellings is interesting from an en-
vironmental point of view, as wood is, in contrast to most
P.J. Fraanje other building materials, a renewable resource with rela-
IVAM Environmental Research tively low environmental impact and a positive effect on
University of Amsterdam the indoor environment (Schneider 1986; Fraanje et al.
P.O. Box 18180, 1990; La¯eur and Fraanje 1997). The utilization of the
1001 ZB Amsterdam, The Netherlands
resource of wood in the building sector, especially when
I thank Prof. Dr. L. Reijnders of the Interfaculty Department of used for structural purposes, can be seen as a high quality
Environmental Sciences (IDES) of the University of Amsterdam application and therefore is a good start for a cascading
for his comments. I am grateful to Mr. W.J. de Graaf of PRC strategy (Fraanje 1997; La¯eur and Fraanje 1997). In
Bouwcentrum in Bodegraven, Mr. F.G.M. van Swam and Mr. general, the use of wood as a building material is envi-
È
R.G.A. Bult of Hugli Pollock Read in Utrecht, Mr. A.G. Oskam of ronmentally preferable to application in products with a
Damen Consultants in Rotterdam (now working at Centre for shorter life time e.g. pallets, as carbon locked up in wood is
Sustainable Building in Utrecht) and Mr. E. Knapper of the
Netherlands Central Bureau of Statistics (CBS), for supplying stored for a longer period of time (Fraanje and La¯eur
data. The research for this article was ®nancially sponsored by the 1994; Fraanje 1997; Drunen 1997).
NWO-research programme for sustainability and environmental Against this background, the Dutch Ministry of Hous-
quality. ing, Physical Planning and Environment (VROM) pub-

2. lished a report within the framework of its programme for working in renovation projects. Although being quantita-
sustainable building in which an effort to increase the tively less important, this article is limited to newly built
application of timber and other wood products in the dwellings. Speci®c data on wood use for renovation of
building sector by 20% is formulated (Boonekamp 1995). dwellings are not available as most of the renovation
Some important institutions in the building and civil en- activities are not recorded.
gineering market, like the Ministry of Public Works and Apart from the new OFD's yearly some 20±30% of all
Water Management as well as two umbrella organisations dwellings are new apartments in multi storey blocks. The
of housing corporations, have committed themselves to amount of wood products per apartment constitutes a
this goal. In 1990, the year of reference of the 20% more fraction of the wood products used for OFD's; in apart-
wood programme, 2,150,000 m3 of wood products were ments built after 1968, 2.5 times less wood is applied than
used in the whole Dutch building sector (residential, non in an OFD (de Graaf 1996). Therefore, within the section of
408
residential and civil engineering) (Boonekamp 1995). For new dwellings only newly built one family houses (without
1990, the use of sawn wood and sheet material was esti- sheds) (OFD's) are taken into account.
mated at an average of 2.8 m3 wood product per new
dwelling, totalling 280,000 m3 net and 400,000 m3 gross 3
(excluding wooden foundation piles) for 97,500 new The use of wood in dwellings
dwellings built in this year (Boonekamp 1995). In 1980, thebuilt between 1969 and 1982
average still was 3.8 m3 wood product per new dwelling There are unfortunately no detailed data covering the use
(Fraanje et al. 1990). of wood in Dutch new OFD's during the 20th century.
Within the framework of the 20% more wood pro- Estimates for the 1900±1945 period suggest that roughly
gramme, the total amount of wood for the new dwellings 10.4 m3 of timber was applied in new OFD's (Botman
has to be enlarged by about 100,000 m3 in the year 2000 1979), whereas only about 8.5 m3 were used in the 1945±
(Boonekamp 1995). The object in view is to double the 1970 period (Botman 1979). It should be noted that earlier
number of timber frame dwellings and to expand the mentioned estimates refer to analyses of typical single
number of wooden carrying inner cavity walls, sloping OFD's; they are not a result of a representative cross-sec-
roofs, wooden foundation piles and sheds (Boonekamp tion. Detailed data are available as to OFD's built between
1995). 1969 and 1982. In this paragraph, the application of wood
Exact data on wood applications in new dwellings since products in new one-family dwellings in the period be-
1982 in the Netherlands are not available, but experts havetween 1969 and 1982 is analyzed. In the period between
the impression that timber products lost ground in the 1969 and 1982, the Ministry of Housing and Physical
residential sector (Eisma 1979) (Boonekamp 1995). Wood Planning (VRO) documented the use of building materials
products seem to be more and more replaced by other in new dwellings, in the Quantitative Material Documen-
materials like concrete and plastics, so the actual trend of
tation (QMD). For a period of fourteen years, a unique
wood utilization in the building sector tends towards the documentation was developed, however published only
opposite direction of the ``20% more wood programme''. partly and at different places (CBS 1976±1984; Eisma 1973±
In an effort to trace the actual development of wood use1980 and van derWerff 1980±1985). In 1983, the Dutch
and to view this against the background of longer term government decided to stop this documentation, due to
trends, it is attempted to determine the average amount of cuts in expenditure. Since then some consultants have
wood in new one family dwellings (OFD) in the Nether- emerged offering information per building product or
lands over the last three decades. OFD's in the Netherlandselement for a commercial price, but no overview is given,
built in this period typically have two ¯oors and an attic.and data are hardly published anymore.
The attention is focused on which building elements are For the QMD, the utilized building material according
usually made of wood and changes therein. Further, the to 1000±1200 plans for new dwellings was recorded. This
total amount of wood in all OFD's in the Netherlands is represented a 1% cross-section of all new dwellings. Such
estimated and a wood balance for 1996 is presented. Data recording was possible, as for all new houses authorization
on the total wood stock and wood ¯ows are relevant for of the central government on the basis of drawings and
determining the cascading potential of timber in the Dutch speci®cations was necessary. It should be noted that as
OFD stock. Finally, some options for an increase in wood plans for building were used, the data for 1969 are rep-
utilization for OFD's are given. resentative for the dwellings built in 1970, etc. A slight
drawback of this method may be that minor differences
2 between plans and the actual dwellings are possible,
New one family dwellings especially where ®nishing materials are concerned.
Most of the timber used annually in the Netherlands is Based on the primary data of the Quantitative Material
applied in the residential sector (NEI 1983; NEHEM 1983; Documentation, Table 1 lists the use of wood in different
Fraanje and La¯eur 1994; Boonekamp 1995). Apart from construction elements and building products for one
the 400,000 m3 for new dwellings, also about 650,000 m3 family dwellings without shed for the period 1969±1982.
(gross) of wood and sheet material (boards, plywood etc) The table is divided into the categories foundation, ¯oor,
was used for renovating dwellings in 1990 (Boonekamp facade, ceiling, wall, roof, door and staircase. Not included
1995). Wood is a light weight, strong, ¯exible, easy in the QMD are skirtings, roof laths, thresholds and indoor
adaptable and workable (on the building site) building ®nishings, as well as timber used for shuttering and scaf-
material which explains its popularity amongst contractors folding. Also excluded from the QMD is the use of wood

3. Table 1. The use of timber and boarding material in different construction elements and building products are given for one family dwellings without shed for the period 1969±1982
È È
Tabelle 1. Die Verwendung von Schnittholz und Brettmaterial in verschiedenen Konstruktionselementen und Baustoffen fur Einfamilienhauser ohne Schuppen in den Niederlanden
von 1969±1982
Wood use in new one family dwellings (OFD's) without shed 1969±1982
Number of OFD's 85100 91300 98500 112400 109900 100600 88600 93900 84500 81900 73300 68900 78375 63950
Building element year 69 70 71 72 73 74 75 76 77 78 79 80 81 82
Foundation pieces 346800 366400 386300 370600 326600 326500 283600 316100 284000 131200 135000 140800 90700 73400
Wooden foundation piles
Floor
Floor beams m3 39600 42600 33473 42311 36107 27145 19605 27188 22431 19162 16641 12513 7949 7642
Wooden ¯ooring 1000 m2 1484 1858 1936 2062 1482 808 610 687 464 392 331 274 121 111
Plywood 1000 m2 28 8 17 58 105 48 124 95 151 117 193
Chipboard 1000 m2 14 77 115 138 105 170 200 85 66 44 42 37
Planks of hardwood 1000 m2 31 5 10 4 16 0 0 22 0 0 0 0 0 0
Parquet 1000 m2 0 0 16 12 13 16 20 16 16 11 14 4 3 0
Facade
Wooden facade 1000 m2 11 1 8 23 nb 11 13 15 0 15 21 40 24 20
Wooden sheatings OFD's 4400 4400 5900 5600 6300 6900 6300 3700 2800 2000 1700 1000
Coniferous window frames 1000 m2 2712 2790 2746 2958 2641 2123 1478 1178 757 670 751 626 625 435
Hardwood window frames 1000 m2 382 422 730 1126 1332 1277 1433 1949 2033 1819 1269 1157 1238 1020
Parapets wood 1000 m2 138 133 189 342 422 460 364 441 448 399 288 187 173 174
Parapets plywood 1000 m2 28 31 46 72 79 70 73 65 63 62 38 51 49
Parapets ®breboard 1000 m2 2 2 5 2 0 1 1 0 0 0 0 0 0
Wooden parapet for balconies 1000 m2 28 42 25 31 14 24 33 30 29 46 16 28 20 9
Ceiling
Fibreboard ceiling 1000 m2 1467 1546 1606 1306 783 391 264 156 93 12 46 7 1 0
Wooden ceiling 1000 m2 234 250 219 356 759 641 535 605 687 289 211 204 103 55
Chipboard ceiling 1000 m2 nb nb 85 67 71 137 77 100 66 35 17 4 10 10
Wall
Wooden carrying inner cavity wall 1000 m2 nb 108 90 99 101 221
Non carrying interior wall chipboard 1000 m2 8 13 nb 425 465 374 328 260 197 130 105 112 120 66
Roof
Beams for roo®ng m3 80800 86900 82324 100482 102876 86139 76077 96266 88838 79523 61608 57123 53053 37893
Boarding spruce 1000 m2 3371 3215 2303 1880 1410 852 400 258 258 155 118 46 9 8
Boarding plywood 1000 m2 21 7 13 83 112 121 69 211 190 189 304 429 521 528
Boarding woodwool(cement) 1000 m2 239 69 174 156 260 120 60 48 35 45 22 0 1 3
Boarding chipboard* 1000 m2 137 65 119 83 278 6086 4839 4681 4435 3003
Reed ¯ax straw boarding 1000 m2 2324 3278 3648 5598 5993 5782 5485 6850 6217 included in chipboard data
Roo®nsulation woodwool 1000 m2 119 76 142 136 63 78 18 0 62 0 0 0 0 0
(Ply)wood for gutters m3 1310 1260 1389 1618 1837 1820 1719 2190 2055 2156 1668 1157 713 575
Wooden dormer pieces 11440 10313 14300 12000 12900 10400 13840 15440 14160 17600 16800 12051 11092 8514
Wooden pivotal window pieces 5170 13630 20680 28012 24252 30174 32430 40138 29422 35881 43150 44556 61100 54219
Doors
Front door coniferous pieces 29500 30400 30000 31300 20000 20900 14000 12700 6100 5700 6800 4400 5300 3900
Front door hardwood pieces 40100 37800 46500 52500 59500 50300 48900 58900 59100 64800 54900 48900 53100 44100
Front door plywood pieces 14300 22000 20600 23600 22000 17900 13500 13800 8600 24200 20500 8200 10900 6900
Kitchen, terrace, balconydoor pieces 129000 131000 139700 164500 169100 157000 137600 160700 148100 141000 108400 93200 91700 70700
Outer doors (total) pieces 212900 221200 236800 271900 270600 246100 214000 246100 221900 222900 181700 154700 161000 125600
409

4. for constructions of inner walls and ceilings. Table 1
582
11100
52200
54358
shows dramatic decrease in wooden foundation piles, ¯oor
beams, wooden ¯ooring and spruce boarding of roofs.
Especially for window frames, inner door frames and front
743
13600
68000
66619
doors, hardwood gained market shares at the cost of co-
niferous wood in the period 1969±1982.
663
4
19600
57600
58565
Estimation of the wood use in one-family
dwellings (OFD's) in 1996
For the period after 1982, hardly any detailed information
729
22830
59800
62305
410 on wood use in new dwellings is available. There are,
however, reports with estimates of wood product market
shares (Dielen 1985; de Graaf 1988; Boonekamp 1995; de
822
37410
66200
69615
Graaf 1996). For 1996, there are also informations available
È
from BuildsightÒ (produced by Hugli Pollock Read, Ut-
recht 1997), a software programme for producers in the
847
29000
68500
71825
building market. Buildsight is based on about 1400 inter-
views on building sites in combination with statistical
information on total area's of roofs, walls etc. of newly
953
36200
74400
79815
built OFD's. As the interviews take place on the building
sites, the data gathered are representative for the same
year, so in contrast to the QMD, the data for 1996 refer to
904
30600
73500
76000
the OFD's built in 1996.
In the following the wood use for 1996 in new OFD's is
estimated. In 1996, 61,007 OFD's were realized, of which
1033
41300
86900
83200
36% were detached, while the other 64% of OFD's were
built in a row (Buildsight 1997). Table 2 summarizes the
wood use in new OFD's in 1996. These elements are the
1158
59700
90200
92800
Table 2. The estimated amount of wood products (in m3) ap-
1230
67800
99300
91100
plied in one family dwellings (without shed) built in 1996
Tabelle 2. Geschatzte Menge an Holzprodukten (m3) in Einfa-
È
È
milienhausern (ohne Schuppen), die 1996 gebaut wurden
1129
67200
93100
81048
Building element m3 (1996)
Foundation
Wood use in new one family dwellings (OFD's) without shed 1969±1982
1082
71600
80993
76158
Wooden foundation piles 5630
* documentation modi®ed in 1978 (accounts for a sudden increase)
Floor
Floorbeams 7240
Plywood/OSB ¯ooring 4935
1016
72200
78204
67905
Facade
Wooden facade 2800
Coniferous window frames (spruce, pine) 2310
1000 pieces
Hardwood window frames 19940
Ceiling no estimation
OFD's
Wall
pieces
pieces
Carrying inner cavity wall 2860
Roof
Beams for roo®ng 58230
Boarding plywood/chipboard/OSB 66175
** after 1975 data are extrapolated
Plywood for gutters 1095
Wooden staircase to ®rst ¯oor
Wooden dormers 1315
Wooden staircase to attic**
Wooden inner door frames
Wooden pivotal windowÃ) 2865
Doors
Wooden outer doors 5320
Inner doors of wood 5490
Wooden inner door frames 2040
Table 1. (cont.)
Staircases
Wooden staircase to the ®rst ¯oor 9900
Staircases
Inner doors
Wooden staircase to the attic 6000
Total 204.145
* wood for window frames of dormers

5. same as the ones covered by the QMD (Table 1), with the hardwood to coniferous wood was about 90:10 in 1990 but
exception of parapets. In order to outline the underlying changed to 85:15 in 1993 (Boonekamp 1994). Probably,
data and assumptions for 1996, the speci®c building ele- this has to do with campaigns against the use of tropical
ments of OFD's built in 1996 in which wood is applied are hardwood in combination with the emergence of techni-
reviewed: cally well-constructed coniferous window frames.
4.1 4.4
Foundation Ceiling
Most wooden foundation piles are made of spruce (about Wood does not play a role anymore in this building element
75%), the other 25% are larch and douglas (de Graaf 1988). except as a construction for ®xing gypsum board. This
According to (Beukema 1997) 1±5% of all dwellings built in application was not recorded in the QMD. For all 110,000
411
1995 by housing corporations is built on wooden piles. dwellings in 1987 de Graaf (1988) estimated a total wood use
Another estimate for 1996 arrives at 1% (Swam 1997). In of over 8,000 m3, mainly used in about 5,500 timber frame
this article, the assumption is made that the market share of houses. For 1996, no data are available, and in accordance
wooden piles amounts 2% of all OFD's, and that every house with Eisma (1979), no estimate is given in Table 2.
is founded on 18 piles. This is less than the percentages of
all new dwellings in 1987 (9%), 1990 (7%), and 1995 (8%) 4.5
(see Boonekamp 1994; de Graaf 1988; de Graaf 1996). Wall
Wooden load carrying inner cavity walls seem to be quite
4.2 popular in new residential buildings. Their market share
Floor was estimated at 20% of all dwellings built by housing
Wooden ground ¯oors have completely disappeared from corporations in 1995 (Beukema 1997). According to in-
the OFD market (Eisma 1979e) and wooden ®rst ¯oors are formation of Buildsight however, the market share
rare in newly built houses. Excluding timber frame amounts to only 5% of the total area load-bearing inner
buildings, the market share of wooden ®rst ¯oors in 1990 walls in all new OFD's; this equals 57,000 m2 in 1996
is estimated at 1 to 2% (Boonekamp 1994). This is in ac- (Buildsight 1997).
cordance with the share of 1% which can be derived from It is unknown, how much wood is used for inner non-
(Beukema 1997). In 1996, there was a total surface of bearing walls. A relatively small amount of timber, mostly
329,000 m2 of wooden ¯oors in all new OFD's (3% of the spruce, is used in combination with gypsumboards
total ¯oorarca in OFD's). The amount of beams necessary (Boonekamp 1994). For 1996 there are no data on wood
is calculated from the ratio ¯oorarea ¯oorbeams in 1982. use in inner walls. In line with Eisma (1979) and
Far out most popular for ¯ooring is sheet material like Boonekamp (1994) this wood use is neglected.
oriented strand board, underlayment and plywood. It is
assumed that the average thickness of the ¯ooring material 4.6
is 15 mm and that the area of wooden (spruce) ¯ooring is Roof
nil (see Table 2). From Buildsight (1997), it can be derived that the total
surface of sloping roofs of OFD's in 1996 was 5,882,000 m2.
4.3 With the ratio of wooden beams to roof area, the total
Facade amount of beams can be calculated. The 1996 market share
Buildsight lists 140,000 m2 of wooden facades, corre- of beams in sloping roofs is estimated at 90%.
sponding to a market share for OFD's of 1.5%. Pre-fabri- For boarding of roofs, it is assumed that 75% of the total
cated facades often have wooden parapets. Buildsight gives sloping roof area of OFD's is boarded with plywood and
no information on parapets; no estimate is given in chipboard, with a thickness of 15 mm. The wood use in
Table 2, as the total surface is not known. In the period ¯at roofs in OFD's (504,000 m2 in 1996) is neglected.
1980±1982 about 3,000 m3 of wood were used for parapets In 1996, 32% of all OFD's had a gutter boarded with
related to window frames. In line with the data for 1987 wood products (Buildsight 1997), most of it plywood (de
and 1990, indicating a market share of 50% for wooden Graaf 1988). Detached houses had a facade of 9.82 in
parapets related to window frames in facades for all width, while an OFD in a row had a facade of 5.43 m in
dwellings (de Graaf 1988; Boonekamp 1995), the market width (Buildsight 1997). If the assumption is made that the
share of wooden parapets for 1996 is estimated at 50%. length of gutters is twice the width of the facade, an esti-
Wood is market leader in window frames for new mate can be derived of the wood use for gutters in 1996.
OFD's. According to (Buildsight 1997), the total window In 1996, 20.5% of all new OFD's had a dormer. The
frame surface in facades of OFD's built in 1996 was market share of wood is put at 50% (see Table 2). This
1,246,000 m2, 92% of which was wood. The total market means an increase compared with the estimated 35%
shares of wood for window frames in all dwellings in 1982, market share for 1990, in line with expert opinion
1987, 1990, and 1995 were estimated at 95, 91, 85, and 90%, (Boonekamp 1994).
respectively (de Graaf 1988; Boonekamp 1994; Boonekamp
1995). Of the wooden frames applied in OFD's in 1996, 4.7
13% is coniferous and 87% hardwood according to Doors
Buildsight (see Table 2). This ratio is roughly in line with In 1996, 232,000 outer doors were used for all new OFD's
estimates of Boonekamp (1995) who states that the ratio of (Buildsight 1997). It is estimated that of this total number

6. there were 25,000 doors for sheds and 10,000 doors to wood is put at 30:70 and for 1981 and 1982 70:30 and for
garages. Furthermore it is assumed that 90% of all outer 1996 at 75:25. The above mentioned estimates are in line
doors of OFD's are made of wood and that the ratio with the data reported by van der Werff (1984b) and es-
hardwood to coniferous wood is 85:15. In 1987, of wooden timates by de Graaf (1988); Boonekamp (1994) and
outer doors in all dwellings, hardwood had a share of 81% Boonekamp (1995).
and coniferous wood of 9%. Merbau was by far the most Table 3 summarizes the total amount of wood products
popular wood used for hardwood outer doors, followed by applied in OFD's built in the period 1969±1982 and in
meranti (de Graaf 1988). 1996, as well as the calculated amount per OFD for these
Most inner doors are made of spruce in combination years. For a good interpretation of the data derived from
with plywood or chipboard. In 1996, the total amount of the QMD, it is important to realise that they are an average
inner doors was 610,000 (Buildsight 1996). Using a con- from three categories of one-family dwellings, namely
412
version factor, the total amount of wood used for inner Housing Act (HA) houses, Premium houses (P) and non-
doors can be estimated. The total area of wooden inner subsidized houses. The ®rst two categories are more (HA)
door frames in 1996 was 1,541,000 m2; this equals a market or less (P) subsidized by the government. It should be
share of wood of 13% (Buildsight 1997). This percentage is noted that in the non-subsidized category, twice or even
lower than the market share for wood of 20% of all thrice as much timber is applied as in Housing Act houses
dwellings built in 1995 by housing corporations (Beukema (Eisma 1979) (NEI 1983). For this reason, the share of the
1997) but higher than the estimates for 1987 (de Graaf non-subsidized category within the OFD sector is also
1988) and 1990 (Boonekamp 1994): 10% and 5±10%, re- given in Table 3.
spectively. Of the wooden inner door frames used in OFD's It should also be noted that for the period of 1969±1982,
in 1996, 86% were made from hardwood, 14% of conifer- the wood use refers to OFD's built in 1970±1983. The
ous wood (Buildsight 1997). In 1982, still 29% of the values for 1996 are representative for the OFD's built in the
wooden inner door frames in all dwellings were made of same year.
coniferous wood and 71% of hardwood (van der Werff It can be learnt from Table 3 that from 1969 to 1982, the
1984b), so between 1982 and 1996 coniferous wood lost total amount of wood products used in all OFD's is almost
market shares at the cost of (mostly tropical) hardwood. constantly declining, the years 1976 and 1977 being the
exception to the rule. In this period, a relative great vari-
4.8 ation in roofs was a fashion among architects, which may
Staircases partly explain the higher average (van der Werff 1980).
About 115,000 staircases were built into all new OFD's in Furthermore, in 1976±1979 the share of unsubsidized
1996 (Buildsight 1997). It is assumed that they are all made houses was relatively high, leading to a higher volume of
from wood. It can be derived from de Graaf (1988) that in wood used in OFD's. In 1969, over half a million m3 wood
1987, of wooden staircases in all dwellings, hardwood had products were used in OFD's, while in 1982 and 1996 only
a market share of 72% and coniferous wood of 18%. 200,000 m3 wood products were applied. In 1972, the year
In Table 2, the estimates of the wood use per building with the highest number of OFD's planned, the total wood
element in 1996 in new OFD's are given. To determine the use was also the highest of the 69±82 period. The total use
amount of m3 per application, use is made of conversion of products of coniferous wood (mainly spruce) declined
factors in line with de Graaf (1996) and Oskam (1995). dramatically in the period 1969±1982. For 1996, the total
use of coniferous wood is estimated less than in 1982. The
5 application of hardwood reached its peak in 1976 and 1977
Total wood use in new OFD's and maintained a yearly level of about 30,000 m3. As far as
The data from Table 1 can be converted into m3 wood sheet material (®bre/chip boards, plywood) is concerned,
products and accumulated to coniferous wood, hardwood it should be noted that, due to changes in the documen-
and sheet material (chipboard, plywood, soft- and hard- tation, a strange jump occurs in the data around 1978. This
board). For the determination of conversion factors, use is is related to a modi®ed calculation method of the boarding
made of information in Oskam (1995); de Graaf (1996). of roofs, being the main outlet for sheet material.
As to the kind of wood product, it should be noted that Coniferous wood was, in 1969, by far the main category,
for kitchen/terrace/balcony doors and for staircases to the accounting for more than 92% of the total amount of
®rst ¯oor, the assumption is made that in the period be- wood, while in 1982 this share had declined to just over
fore 1976 the ratio between hardwood and coniferous 50%. In 1996, coniferous wood makes up 48% of all wood
wood was 20:80 and afterwards 80:20. For staircases to the products applied in OFD's. In 1969, solid tropical hard-
®rst ¯oor, the ratio between hardwood and coniferous wood had a share of only 3% of the total amount of wood
wood is estimated at 20:80. For pivotal windows, the as- used in OFD's. In 1996, 14% of all wood products in OFD's
sumption is made that until 1975 all of them were made were made from solid tropical hardwood. For sheet ma-
from coniferous wood, after 1975, 10% is assumed to be terial (in 1969 mainly ®breboard, chipboard and plywood)
made of hardwood. For wooden dormers, the assumption the share increased from 5% in 1969 to 38% in 1996
is made that until 1975 all of them were from coniferous (mainly chipboard, OSB and plywood), with a notably
wood, after 1975, 80% is assumed to be made of hardwood. strong increase in chipboard during the seventies.
For wooden inner door frames the assumption is made Per OFD, the average wood use dropped from 6.19 m3
that until 1975 they were all made of coniferous wood, in 1969 to 3.22 m3 in 1982 and 3.35 m3 in 1996. Excluding
between 1976 and 1980 the ratio hardwood to coniferous wooden foundation piles from the analysis in 1969,