This document discusses the properties and uses of wood. It notes that wood is strong yet lightweight, making it suitable for building structures, furniture, tools, and other applications. The document outlines the differences between hardwoods and softwoods, and describes how wood properties depend on grain direction. It also discusses the advantages of using wood in construction, including its flexibility, thermal and sound insulation properties, fire resistance, and status as a renewable resource.

1. Dr f Dejahang (BSc CEng, BSc (Hons) Construction Mgmt, MSc, MCIOB,
PhD)
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Dr f Dejahang BSc CEng, BS (Hons) Construction Mgmt, MSc, PhD

4. WOOD
 The Mechanical properties and availability of
wood have made it a natural material for:
 building structures
 Furniture
 Tools
 Vehicles
 decorative objects
 Etc

5.  Worldwide it is used more than metal or
plastic.
 Wood is a natural product and when used
responsibly is a sustainable resource which
need not result in damage to the
environment.
 Forests can be protected by recycling and
reusing the wood, using less wood and by
supporting sustainable forest management

6.  The strength of wood is highly dependent
on the loading direction.
 Wood is strongest in tension along the
fibres and is weakest in the radial and
tangential direction.
 When loaded in its strongest direction
(longitudinal along the grain - wood can
have a strength to weight ratio advantage
relative to steel of 2:1.

7.  When wood is loaded in other directions (radial
and tangential to the grain this advantage
disappears.
Wood Types
 It is customary to describe wood using the
following terms.
 there is some degree of overlapping in practice.
 Carpentry- applying to structural work in buildings
and ships

8.  Timbering - applying to temporary
work such as formwork for concrete,
gantries and shoring
 Joinery -wooden structures inside
buildings, such as doors and window
frames
 Cabinetwork - cabinetry - making
furniture

9. Hardwoods
 Hardwood trees are generally broadleaved
trees.
 These tree species are deciduous, retaining
their leaves only one growing season.
 The designation Hardwood trees does not
necessarily relate to the hardness of the wood.
 Hardwood trees are also called broad leaf trees
or deciduous trees.

10. Typical hardwood trees include:
 Ash
 Elms
 Oak
 Maple
 Walnut
 Hickory
 mahogany, and walnut.

11. Woods grown in tropical
climates are generally
hardwoods.
Hardwood have shorter fibres’
compared to softwood.
Some hardwoods are
evergreen.

12. Softwoods
 Softwoods are one of the botanical groups
of trees that have persistent needle-like or
scale-like leaves;
 softwoods are evergreen and have longer-
length fibres’ than hardwoods.
Softwood trees include pines, spruces,
firs, cedars.

13.  The yew is one of the few types of
softwood that is native to the UK.
 There are a number of softwoods
(yew) that are harder and tougher
than many hardwoods
Larches, including tamarack, are
exceptions, being deciduous
"softwoods".

14. Use of timber in
construction
 Today, when architects and engineers
design landmark buildings like bridges or
government offices, schools or Factories,
they look to timber to express a
contemporary beauty which is nonetheless
rooted in nature and a respect for the
environment.

15.  The flexibility of lightweight modular timber
construction is particularly suited to multi-purpose
halls because of its ready adaptability.
 Wood is a high-performance material
 low in weight
 high in density, with excellent load-bearing and
thermal properties
 and the availability of a wide range of timbers,
each with its own characteristics, means wood
can be suitable for most special requirements.

16. One specific advantage of wood
is its ability to reduce energy
use.
Timber construction has a
higher heat insulation value
than conventional construction
methods, even with lower wall
thicknesses.

17.  An external wall constructed using
timber may have only half the
thickness of a brick or concrete wall
 yet provide double the thermal
insulation value
 while at the same time avoiding the
thermal bridging common with other
construction methods.

18. Flexibility
 The flexibility of timber construction methods
makes it easier to vary a building’s orientation
on site, its floor plan, the number of rooms, the
interior design and the overall appearance
 while timber’s thermal efficiency means walls
can be slimmer
 releasing up to 10% more space than other
building methods.

19. Fire prevention
 Unlike many other materials, timber behaves
predictably in fire
 forming a charred surface which provides
protection for the inner structure
 timber elements can remain intact and fully load-
bearing during a fire.
 The fire-retardant detailing of modern timber
construction prevents cavity fires and the spread
of combustion gases

20. Sound insulation
 Modern timber buildings readily
comply with sound insulation
standards through using a layered
structure of different materials.
 Even more demanding standards can
be met using a number of different
design solutions.

21. Durability
 With good design and correct detailing,
structural wood needs no chemical
treatment to achieve a long life.
 Wood is resistant to heat, frost, corrosion
and pollution;
 the only factor that needs to be controlled
is moisture

22.  Wood is a unique and renewable material
 As trees grow they naturally absorb CO2
from the atmosphere
 Wood is the building material of the
future
 The materials used in a typical 2-
bedroomed semi-detached house in
England emit about 14 tonnes of CO 2 in
their extraction and manufacture.

23.  By using timber frame, you can save
up to 9 tonnes per house;
 by increasing the amount of wood
products such as:
 wood windows,
 doors
 Flooring
 They saves still more CO 2
 Recycling and re-use of wood

24. Reconstituted wood-based products

25.  Similarities and differences between steel and
timber as structural materials.