This document provides information on the material properties and characteristics of timber. It discusses that timber is a natural product made of wood from trees. It grows in rings and its properties vary based on species and growth conditions. The document outlines the production of wood within trees and describes key characteristics like grain, moisture content, drying, and shrinkage. It also discusses grading standards and jointing methods for timber.

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timber in internal applications
Material Basics
Timber and Wood Products
Basic material properties and
characteristics.

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timber in internal applications
Material Basics
The nature of timber
• Timber is a natural
product, drawn from
the wood in the
trunks of trees.
• Its character is
consistent with the
species of tree and
the form and growth
over time of the
wood in it.
Regrowth in a native forest

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timber in internal applications
Material Basics
Tree growth
• New wood on outside of tree
– oldest wood on the inside
– youngest wood on the outside
– diameter largest at the base
– one ring (layer) per growing season
• Tree in forest grows toward light
– trunk is straight
– lower branches die
– leaving small knots in wood
• Bark protects wood from damage
– the tree sheds bark each year

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timber in internal applications
Material Basics
Production of wood
Cambium - growth cells
• wood cells created on the inside
• bark cells created on the outside
Sapwood - newest wood
• on the outside of tree (~ 1-3 cm)
• takes nutrients from root to leaves
Heartwood - older wood
• cells closed - can’t pass nutrients
• storage for waste - extractives
Pith - the start of growth in the tree
• the original sapling

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timber in internal applications
Material Basics
Variation: fibre & grain
• The cell structure is designed to serve particular
functions in a tree.
• Its properties vary in different directions.
rays
rays
cells
fibres
vessels
hardwood earlywood
rays
latewood
softwood

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timber in internal applications
Material Basics
Variation: species & growth
• Species and
genetics:
– selected stock or
natural seed.
• Climate:
– wet or dry, cold or
warm.
• Arrangement:
– native forest or
plantation.

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timber in internal applications
Material Basics
Each piece is unique
Myrtle burl veneer
Quarter sawn hardwood

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timber in internal applications
Material Basics
Properties are variable
• Drying (seasoning) & shrinkage
• Strength & hardness
• Durability
• Appearance

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timber in internal applications
Material Basics
Moisture and drying in wood cells
removed
bound
waterSeasoned
timber
15% MC
100% MC
Unseasoned
timber
Growing
tree
free water
25% MC
fibre saturation
bound water
Partially
seasoned
timber

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timber in internal applications
Material Basics
Benefits of drying
• Drying timber
increases its:
– strength;
– stiffness;
– stability
– durability; &
– ease of fastening.
• It is ideally dried to a
moisture content in
equilibrium with its
service environment.
Checking the moisture content

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timber in internal applications
Material Basics
Timber shrinks as it dries
• It shrinks at different rates in
different directions.
• Once dry, it will expand &
contract to be in equilibrium
with changing local conditions.
Shrinkage from 12% to 25% MC
Radiata pine Rad 3.5% Tang 4%
Hoop pine Rad 2.5% Tang 3.5%
Cypress Rad 3.5% Tang 4%
Spotted gum Rad 4.5% Tang 6%
Karri Rad 4.5% Tang 10%
Sydney blue gumRad 5% Tang 9%
Grey Ironbark Rad 5.5% Tang 7.5%
Mountain ash Rad 6.5% Tang 13%
SoftwoodHardwood
Tangential
shrinkage
Radial
shrinkage
Longitudinal
shrinkage

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timber in internal applications
Material Basics
Shrinkage in sawn sections
• Tangential shrinkage
is the highest;
• So, the growth rings
tend to shorten as the
timber dries.

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timber in internal applications
Material Basics
Timber dries at different rates
• Pines have a porous cell structure:
– They can be dried very quickly.
– Turnaround time from saw to store can
be as low as a week.
• Hardwoods have a non-porous cell
structure:
– The moisture must diffuse through the
cell wall.
– Drying can be very slow.
– It must be done carefully.

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Material Basics
Grain, strength & stiffness
Direction of grain
Strong parallel to grain & stiff parallel to grain
Weak perpendicular to grain
Properties of the grain

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timber in internal applications
Material Basics
Summary of characteristics
• Timber is a natural material
• Each piece is unique in fibre, texture and
colour
• Its strength is dependant on the
properties of the wood and the slope of
the grain
• It takes up and gives up moisture
• It expands and shrinks as it does so
• It deteriorates in line with exposure

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Material Basics
Timber products
• Timber is available in a wide range of
products and species including:
– Solid sawn, moulded and laminated timber;
– Veneer;
– Plywood; and
– Wood panels.

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timber in internal applications
Material Basics
Timber products: sawn
• Hardwood or
softwood.
• Solid timber cut from
a log and dried.
• It is a versatile
material used for
moulding, frames and
exposed structures.
• Size is restricted.

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timber in internal applications
Material Basics
Timber products: mouldings
• Hardwood or
softwood.
• Solid seasoned
timber milled to a
wide variety of
shapes.

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timber in internal applications
Material Basics
Timber products: glue laminated
• Small pieces of
timber glued
together to form a
larger element.
• Used as both a
structural and
finishing element.
• Size is limited only
by transport
capacity.
bench top
beam

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timber in internal applications
Material Basics
Timber products: curved glulam
• Glue laminated
material can be
curved.
Curved bar

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timber in internal applications
Material Basics
Timber products: veneer
• Thin layers of solid
wood sliced from a
flitch or peeled from a
log and dried.
• High quality material
is used as a
decorative finish.
• Lower grade material
is used to make
plywood, LVL and
similar products.
Veneer leaf

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timber in internal applications
Material Basics
Timber products: plywood
• Layers of veneer
glued together so
that the grain
direction alternates
between layers.
• Usually produced in
sheets.
• Very good in a
structure, as a lining
and as a flooring
surface.

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timber in internal applications
Material Basics
Timber products: wood panels
• Panels made from
wood or wood fibres
bound together with
glue, or other binder:
– Particleboard
– Medium Density
Fibreboard (MDF)
– Hardboard
– Core board
MDF sheet

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timber in internal applications
Material Basics
Appearance grading
• Production process
of sorting products
into groups with
similar
characteristics &
properties.
• Timber identified by
calling up a specific
grade.
Visual grading

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timber in internal applications
Material Basics
Grading standards
• AS 1810-1995 Timber - Seasoned
cypress pine - Milled products
• AS 2796-1999 Timber - Hardwood -
Sawn and milled products
• AS 4785-2002 Timber - Softwood -
Sawn and milled products

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timber in internal applications
Material Basics
AS 2796 Hardwood - Sawn & milled
• This standard defines the requirements
for hardwood used for visual
applications: architectural (flooring, etc),
lining & cladding; &
• It is in two main sections:
– product requirements; &
– visual grades.

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timber in internal applications
Material Basics
Appearance grading - rules
• Establish permissible limits on:
– gum vein
– knot size & frequency (location unimportant)
– splits, cracks, checks (size and frequency)
– stain (colour), grain uniformity
– utility: want, wane, cup, bow, spring, twist

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timber in internal applications
Material Basics
Grade range
• From select grade
– uniform wood with
few natural features
• Through to high
feature grade
– including lively
natural feature as
part of a desirable
aesthetic.

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timber in internal applications
Material Basics
AS 2796 Hardwood - Sawn & milled
• Tolerances are established for the major
product groups (not grades):
– Joinery and dressed boards;
– Strip and overlay flooring, mouldings, sawn
boards for feedstock; &
– Light decking, lining boards, cladding, facia,
bargeboards.

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timber in internal applications
Material Basics
AS 2796 Part 1 - distortion
• Bow - depends on
thickness
• Spring - dependent on
width
• Twist - separate limits
for less or more than
25 mm thick
• Cup - 1mm per 100
mm width

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timber in internal applications
Material Basics
AS 2796 Part 1
• No lyctid susceptible sapwood is
allowed. (Lyctids are small wood eating insects.)
• MC anywhere in a piece must be
between:
– 9-14% for most products including flooring.
– 8-13% for parquet & furniture components.

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timber in internal applications
Material Basics
AS 2796 Hardwood - Sawn & milled
• The standard recognises feature as a
desirable visual characteristic;
• Therefore, distortion and machining
tolerances are associated with product,
not grade; &
• The timber can then be specified with
the desired appearance for any function.

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timber in internal applications
Material Basics
AS 4785 Softwood - Sawn & milled
• Layout is similar to AS 2796 with product
requirements & visual grades;
• Visual grades are Clear, Appearance,
Select, Standard, Utility Grade;
• With radiata, there is a much greater use
of industry grades; &
• Terms can vary between companies.

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timber in internal applications
Material Basics
Jointing
• Timber is a highly
versatile material
that can be shaped
and joined easily.
Mortice and tenon Housed
Half housed

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timber in internal applications
Material Basics
Jointing methods
Overlap Fixing blocks
DowelBiscuit

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timber in internal applications
Material Basics
Conclusions
• Timber is a natural product.
• It has been used for centuries.
• Skilled use and understanding of the
material can yield excellent results.