Modern Timber Construction & Application in Buildings

TIMBER CONSTRUCTION
BIA1021 - Materials & Construction 1
for
Bachelor of Science of Architecture
Session 2024/25, Semester 1
15 October 2024 (Week 2)

TIMBER
• The wood which is suitable or fit for
engineering construction or engineering
purpose is called timber
• It should have structural as well as
aesthetic merits.

Name origin
To build
Timbrian
(English
word)
Timber
USES OF TIMBER
• Building Construction
• House Post Construction
• Beams And Rafters
• Construction Of Bridges And Boats
• Furniture And Instruments
• Railway Sleepers And Packing Cases
• Toys And Engraving Work
• Railway Coach Wagons
• Formwork Of Cement Concrete

General Properties
• Color – a darker color in wood indicates greater durability.
• Odor – it is present only on freshly cut trees.
• Hardness – is the ability of wood to withstand indentations caused by harder
bodies.
• Density – densest woods are generally the strongest.
• Grain - Depending on the actual alignment, the grain may be straight, spiral,
interlocked, wavy or irregular.
• Spiral Grain
• Interlocked Grain
• Wavy Grain
• Texture - In hardwoods, the texture depends upon the size and distribution
vessels and rays. In softwoods, it is determined by the size and distribution of
tracheid.

Identifications of Timber
• Luster- is the ability to reflect light beam pointedly.
• Workability- the relative case in which wood is shaped cut and fastened
together than the others.
• Warping- is the general term used to describe any variation from a true
surface.
• Moisture content- is a percentage of the mass of water over the mass of
wood fibre in a piece of timber.
• Specific Gravity- is the ratio found by dividing the weight of a substance by
the weight of an equal volume of pure water.

Moisture of Timber
• Moisture Content - It is one of the most important characteristics of timber
that affects its use on the site performance.
• Equilibrium Moisture Content (EMC) - moisture content of wood changes in
response to the temperature and humidity of its surroundings.
• Fibre Saturation Point (FSP) – when the cell cavities are empty but the cell
walls still retain their bound water.

SEASONING
• Fresh timber which is obtained from trees have about 30 to 40
percent sap or moisture.
• This sap is very harmful for the life of the timber.
• Therefore it is essential to remove the sap by applying certain
special methods.
• All such methods are collectively termed as seasoning of timber.

TYPES OF TIMBER SEASONING
Timber
seasoning
Artificial
seasoning
Water
seasoning
Natural
seasoning

Artificial
seasoning Kiln seasoning
Chemical seasoning
Electric seasoning

Advantages of seasoned timber
• It has reduced weight
• Strong and durable
• Resistance to decay and rot
• Takes high polish
• Easier to work with
• Lasts longer

Defects in timber
Defects caused in timber may be basically classified into two categories:
 Internal Defects – due to factors affecting the growing tissue or the tree.
 External Defects – due to external agents or subsequent treatment of timber.

Defects in Timber
• The defects occurring in the timber
are grouped as follows :-
1. Defects due to conversion
2. Defects due to fungi
3. Defects due to insects
4. Defects due to natural forces
5. Defects due to seasoning

Defects due to conversion
• During the process of converting timber to the
commercial form, the following defects occur:-
a) Chip mark- marks or signs placed by chips on
the finished surface of timber.
b) Diagonal grain- Due to improper sawing of
timber.
c) Torn grain- Caused when a small depression is
formed by falling of a tool or so.
d) Wane- Denoted by the presence if original
rounded surface on the manufactured piece of
timber.

Defects due to fungi
Fungi attack timber only when the following two conditions are
satisfied simultaneously:
i. The moisture content of timber is above 20%.
ii. There is presence of air and warmth for the growth of fungi.
Following defects are caused in the timber by the fungi:
• Blue stain- sap of wood is stained to bluish color.
• Brown rot-decay or disease of timber.
• Dry rot- converting of timber into dry powder form.
• Heart rot- indicated by the hollow sound given out when struck with
a hammer.
• Sap strain-loses the color of sap.
• Wet rot- causes chemical decomposition of wood of timber.
• White rot- opposite of brown rot.

Defects due to insects
and
natural forces
Insects which are usually
responsible for the decay of
timber:-
• Beetles
• Marine borers
• Termites
Natural forces causes:
• Abnormal growth
• Rupture of tissues

Defects due to natural forces
• Burls- growth of the tree is upset and irregular projections appear.
• Callus- soft skin which covers the wound of the tree.
• Chemical stain- discoloring of wood.
• Coarse stain- annual rings get widened.
• Dead wood- timber obtained from dead trees.
• Druxiness- white decayed spots which are concealed by healthy wood.
• Foxiness- indicated by red or yellow tinge in wood.
• Rind galls- these are typical curved swelling formed upon the trunk of the
tree by successive layer of the sapwood.
• Twisted fibers- fibers or wandering hearts are caused by the prevalent
wind turning or twisting the tree at its young age constantly in one
direction.
• Upsets- are clipping or buckling of fibers caused by crushing of fibers
when the trunk is felled violently over a rocky surface.
• Water stain-
• Wind cracks- are shakes on the outside of a log due to the shrinkage of
the exterior surface caused by the atmospheric influences.

Defects due to seasoning
Following defects occur in the seasoning process of wood:
• Bow- a curvature of the timber in the direction of its length.
• Case-hardening- it is due to the unequal drying of the exterior surfaces under
compression and the interior surfaces under tension due to rapid drying.
• Check - these reduce the shearing resistance of the wood.
• Collapse - the cells of timber are flattened due to excessive shrinkage.
• Cup- a curvature in the transverse direction of the timber.
• Honey-combing- separation of the fibers in the interior due to drying stresses.
• Radial shakes
• Split- separation of the fibers along the grain and extends from one end of the
plank to the other.
• Twist- a spiral distortion along the length of the timber.
• Warp

Shakes
• Shakes- or cracks are caused by the rupture
of tissues resulting in partial or complete
separation of the fibers along the grain.
Star Shakes
Heart Shakes
Cups Shakes
Ring Shakes
Radial Shakes

Objects of preservation of timber
• The preservation of timber is carried out to achieve the following three
objects:-
• To increase the life of timber structures.
• To make the timber structures durable.
• To protect the timber structures from the attack of destroying agencies such as
fungi, insects, etc.

TIMBER PRESERVATIVES
The main classes of timber preservatives are :
• Ascu treatment
• Chemical salts
• Coal tar is highly effective against fungi.
• Cresote oil
• Oily substances insoluble in water
• Water soluble salts
• Zinc chloride is the most extensively used of this type. It is clean and
odourless.

• Scientifically prepared
timber in a factory.
• They possesses
desired shape,
appearance, strength,
etc.
Industrial
timber
Veneers
Plywoods
Fibre boards
Impreg timbers
Compreg timbers
Block board and lamin board
Glulam
Flushdoor shutters
Particle board or clip board
Hardboard

Veneers (IS:303-1989)
• These are thin sheets or slices of wood if superior quality whose thickness varies
from 0.40 mm to 6 mm or more.
• They are obtained by rotating a log of wood against a sharp knife of rotary cutter
or saw.
• The veneers after being removed are dried in kilns to remove moisture.
• Veneers may be glued with suitable adhesives on the surface of inferior wood.
• Used to produce plywood, batten boards and lamina boards.
• May be fixed on corners or bent portions.
• Indian timbers suitable are mahogany, oak, rosewood, sissoo, teak, etc.

Plywood
• Plywood is a panel formed of three or more layers of veneer glued together, usually with
the grain of adjacent veneers running at right angles to each other, held in position by the
application of suitable adhesives.
• The perpendicular placing increases longitudinal and transverse strengths of plywood.
• The plywood are available in different commercial forms such as batten board, lamina
board, metal faced plywood, multiply, three-ply, veneered plywood, etc.
• According to CPWD specifications, plywood for general purposes are of following three
grades:
i. Boiling Water resistant
ii. Warm water resistant
iii. Cold water resistant

Advantages of plywood
It has a good strength both across as well as along the grain.
Plywood has better splitting resistance due to grains in adjacent layers running
at the right angle and nailing and screwing even closed to the edges in safe.
Can easily be bending to a curvature limited by the tensile and the compressive
strength of the other plies.
The face piles made at different heartwoods show great aesthetic variety in
grain pattern and color.

Hardwood
• Hardboard - manufactured from raw materials like
wood waste, veneer manufacturing, furniture making.
Sizes of hardboards
 Medium hardboard
 Normal hardboard
 Tempered hardboard
Thickness of Hardboards

Width and Length of Hardboards

• Fibre Board: Rigid boards and they are known as the oressed wood or
reconstructed wood. The fibre boards form an ideal base for all types f
decorative finishes like distemper, oil paint, etc.
• Impreg timbers: Timber which is fully or partly covered with resin and used
for moulds, furniture, decorative articles, etc.
• Compreg timbers: Almost with same properties as of above, it is treated
under high pressure. The strength and durability is more.
• Block boards or lamin boards: it is a board having core strips, each not
exceeding 7 mm in thickness
• Glulam: Glued and laminated wood made of solid wood.
• Flush door shutters: More popular for interior works.
• Particle boards: is a board manufactured from particles of wood or other
lingo cellulose materials.

Batten
Baulk
Board
Deal
End
Log
Plank
Pole
Quartering
Scantling
Market
forms of
timber

Batten has
breadth and
thickness
which does not
exceed 50
mm.
Baulk is a
roughly
Squared
timber piece
and it is
obtained by
removing bark
and sap wood.
Board is a
plank whose
thickness is
less than 50
mm and width
exceeds 150
mm.
Deal is a piece
of soft wood
with parallel
sides which
has a width
limited upto
230 mm.
End is a short
piece of
batten, deal,
scantling.

Log is a trunk of
tree obtained
after removal of
branches.
Plank is a timber
piece with
parallel sides.
Pole is a sound
long log of wood.
Also called as a
spar.
Quartering is a
square piece of
timber.
Scantling are the
pieces if
miscellaneous
sizes of timber
sawn out of a log.

Joineries
• Joinery is a part of woodworking that involves joining together pieces
of timber or lumber, to produce more complex items. Some wood joints
employ fasteners, bindings, or adhesives, while others use only wood
elements. The characteristics of wooden joints - strength, flexibility,
toughness, appearance, etc. - derive from the properties of the materials
involved and the purpose of the joint. Therefore, different joinery
techniques are used to meet differing requirements. For example, the
joinery used to construct a house can be different from that used to
make puzzle toys, although some concepts overlap.

Joint Explanation
Butt Joint The end of a piece of wood is butted against another piece of wood. Simplest and weakest joint.
Lap Joint The end of a piece of wood is laid beside and connected to another piece of wood. The next simplest
and weakest joint.
Bridle Joint This joint is where the through mortise is open on one side and forms a fork shape. The mate has a
through tenon or necked joint. Used to join rafter tops, scarf joints and sill corner joints in timber
framing.
Dowel Joint The end of a piece of wood is butted against another piece of wood. A very common joint in factory-
made furniture.
Mitre Joint Similar to a butt joint, but both pieces have been beveled.
Finger Joint Also known as a box joint, is a corner joint with interlocking fingers. Receives pressure from two
directions.
Dovetail
Joint
A form of box joint where the fingers are locked together by diagonal cuts. More secure than a finger
joint.

Dado Joint Also called a housing joint or trench joint, a slot is cut across the grain in one piece
for another piece to set into.
Groove Joint Like the dado joint, except that the slot is cut with the grain.
Tongue and
Groove
Each piece has a groove cut all along one edge, and a thin, deep ridge (the
tongue) on the opposite edge.
Mortice and Tenon A stub (the tenon) will fit tightly into a hole cut for it (the mortise). The traditional
method of jointing frame and panel members in doors, windows, and cabinets.
Birdsmouth Joint Also called a bird's beak cut, this joint used in roof construction. A V-shaped cut in
the rafterconnects the rafter to the wall-plate.
Cross Lap A joint in which the two members are joined by removing material from each at the
point of intersection so that they overlap.
Splice Joint A joint used to attach two members end to end.

Heavy Hardwood- Chengal
• Chengal is considered the number one wood (classified as heavy
hardwood) of Malaysia and export of logs is prohibited due to its scarcity.
• Planing is known to be easy and a smooth finish is easily achieved
• Boring is not hard
• Turning is easy as well and a smooth finish is achieved
• Nailing is very difficult and mostly a hole has to be predrilled to receive a
nail
• The timber is classified as naturally durable and is normally very resistant
to termite attack and fungal infestation .

• The timber is suitable for all forms of heavy construction, railway sleepers, heavy duty
furniture, laboratory benches, bridges, marine construction, boat building, telegraphic and
power transmission posts and cross arms, piling, mallets, flooring (heavy traffic), decking,
vehicle bodies (framework and floor boards), fender supports, cooling towers (structural
members), staircase (balusters, carriages, handrails, newels, risers, stringers, treads,
bullnoses, round ends and winders), columns (heavy duty), door and window frames and
sills, tool handles (impact), carving works and other uses where strength and durability are
required.
• On the Malay Peninsula Chengal has been used as the wood of choice for house and
boatbuilding. It is sometimes referred to as the "Malaysian Teak".

Keruing- Middle Hardwood
• Keruing is the name given to the timber yielded from more than 70 species of the
genus Dipterocarpus. This group of large hardwoods is indigenous to South East Asia,
where the species are harvested from managed forests with regeneration programs.
• Keruing timber is low maintenance, hardwearing and ideal for outdoor furniture use. The
wood is strong and classified as durable, making it useful for construction purposes. Other
common uses include internal flooring, protected framing and boards, internal joinery and
mouldings, lining, paneling and framework. Preservative-treated material is used for poles,
piles, sleepers and cross-arms. It is often used as a cheaper alternative to oak for heavy
construction, decking, vehicle building and sleepers, and it is also in plywood.
• Across this entire species of keruing, a wide variety of heartwood hues are available,
including deep-pink, orange-pink, and purple-red. The most common heartwood is red-
brown.

Malaysian Rubber Wood
• Rubber wood is a light-colored medium-density tropical hardwood obtained from
the Pará rubber tree (Hevea brasiliensis), usually from trees grown in rubber
plantations.Rubberwood is commonly advertised as an "environmentally friendly"
wood, as it makes use of plantation trees that have already served a useful
function.
• In 2002, the Malaysian Ministry of Primary Industries marketed it under the name
"Malaysian Oak.
• Rubberwood has a dense grain that is easily controlled in the kiln drying process.
Rubber-wood has very little shrinkage making it one of the more stable
construction materials available for furniture, toys and kitchen accessories. It is
easily worked, and takes on stains uniformly. As with all hardwoods, rubberwood
comes in varying degrees of quality.
• It is not suitable for outdoor use, as rain can leach the protective chemicals from
the wood, exposing it to fungus and insect attacks. Excessive moisture will also
cause the wood to warp and rot.

ADVANTAGES OF TIMBER
• Can be easily handled and joined.
• Timber can be used for both load bearing structures and non-load bearing instruments.
• It can be easily converted to any shape and size.
• With the advent of superior adhesives and other forms of timber connectors.
• The wastage in timber construction is less because all wastes can be put one use or the
other.
• It has high resale and salvage value.
• Timber has better insulating properties than any other materials.
• Durability of timber can be very high, if properly seasoned and preserved.
• Timber constructions are light in weight and strong and can be made economical.
• For aesthetic and decorative appearance.
• Easily available.
• High energy efficiency.

What is Vernacular Architecture?

According to its etymology, “verna” means native and
“architecture” is to design buildings, thus vernacular
architecture is an architecture style that is built to meet the
present needs, keeping in mind the local climate,
culture, and materials.
- https://www.re-thinkingthefuture.com/

“Vernacular architecture can be defined as a type
of local or regional construction, using traditional
materials and resources from the area where the
building is located.”
- ArchDaily (2023)

Image by Iain Buchanan
Surrounding Setting
Space Arrangement
Construction Method
Climatic Responsive Design
Social & Cultural
The Village Setting

The Village Setting
Image by Lim Jee Yuan (1987)

Surrounding Setting
Centric
Linear

Space Arrangement
Image by Lim Jee Yuan (1987)

Space Arrangement
Image by Mohd Firrdhaus Mohd Sahabuddin (2012)
Lantai Jarang

The Advantages and Disadvantages of
Timber Construction

Timber Construction
Advantages Disadvantages
• Being light in weight, it is preferred for building works in earth
quake prone regions.
• It is an excellent material for decorative and general use
furniture. Lot of other internal decorations can be carried out
with it.
• It can with stand, shocks better than iron and concrete.
• It is good insulator of electricity and heat.
• It is good sound absorbing material.
• Timber can be easily strengthened by attaching steel or other
material with it.
• Easy to cut and reshape as per desired dimensions.
• Locally available. The workers of woodwork easily available.
• Catches fire easily.
• Can be affected by termite.
• Not suitable for heavy loads and
multistoried structures.

The Principles of Timber Construction

The Basic Construction Methods

The Floor and Wall Construction

Detail & Specification in Timber Construction

Cross Section of
a Timber House

Modern Timber Construction & Application in Buildings

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