503 335w3 20 wood and application intro

www.csaw.utas.edu.au Management for sustainability Content • Definitions and concepts • Key characteristics of wood • Key requirements of acceptance in applications www.csaw.utas.edu.a

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Characteristics of wood and the

requirements of application

Key concepts in wood properties

and applications

www.csaw.utas.edu.au

Management for sustainability

Content

•  Definitions and concepts

•  Key characteristics of wood

•  Key requirements of acceptance in applications

KDA503/335 Timber, its origin and characteristics

Wood and its characteristics

Definitions and concepts

Wood means:

•  the hard, fibrous substance

lying under the bark in a tree

or shrub

Taken together, the wood has

resource characteristics:

•  These are the physical

properties of the material in

the log and the log s form

•  Developed in response to the

tree s evolutionary needs

Timber means:

•  The range of timber and wood products available to meet society’s needs

These have product characteristics largely determined

by manipulating the resource characteristics during

production

Applications means:

•  Society’s uses for wood and

timber For solid wood products,

this is predominantly in building

Applications generally have

performance requirements

that are generally set

independently of the resource or

material characteristics

Timber use in Australia

•  Australia’s timber industry sells:

–  About 75% of production

to the residential building sector, mainly for detached house

–  About further 10% to the non-residential sector

•  In short, the timber industry make building materials

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Key characteristics of wood and timber?

•  natural

•  renewable

•  variable (anisotropic)

•  hygroscopic

•  bio-degradable

•  democratic

•  versatile

Key requirement of acceptance in applications?

•  regulatory compliant performance

•  market compliant performance

•  quality (fit-for-purpose)

•  available

•  economic

Key characteristics of wood

Natural

existing in or caused by nature; not made or caused by humankind

•  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

of the wood in it over time

Regrowth in a native forest

Renewable - conditionally

not permanently depleted when

used

•  Renewable resources are:

–  natural forces or

–  organic - things that can be

harvested and regrown

•  Most renewable building

materials are things grown

•  They require both time and

space to renew themselves

•  They can be used sustainably

if the rate of use is less than

the rate of renewal

Variable / anisotropic

having physical properties that have different values when measured in different directions

•  Timber’s variability doesn’t stop there It also varies with its original location in the tree, and the tree’s age, source, and species

zone of wood property change

zone of unchanging wood properties

(age of deposited wood – years)

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Hygroscopic

the ability to loose or gain

moisture content with

fluctuations in environmental

humidity

•  When harvested, timber holds

a significant volume of water

•  After seasoning, timber

absorbs or loses moisture to

remain in equilibrium with the

surrounding atmosphere

•  As it absorbs moisture, it

expands As it loses moisture,

it shrinks

Hardwood drying in racks

Biodegradable

capable of being decomposed by bacteria

or other living organisms

Wood can be consumed by:

•  fungi (or decay) when its

MC is regularly higher than about 20%

•  insects and termites

•  marine organisms

Lyctid borer attach in sapwood

Democratic

appealing to or adapted for

the benefit of people at

large

•  Timber use isn t

necessarily limited by skill

or equipment

•  It is relatively easy to

make significant and

useful items with wood

•  Increases in skill can lead

to significant increases in

output

Hand-made WW2 igloos

Versatile

able to adapt or be adapted

to many different functions or activities

•  Wood is available in many forms

–  Rounds, sawn, glulam, ply, LVL, fiberboard, etc

•  Each of these forms can

be assembled or combined in many ways

Key requirements of acceptance in

applications

Regulatory compliant performance

performance level dictated

by regulation

•  In Australia, most timber

is used in building, and building is regulated by the National

Construction Code (NCC)

•  This establishes the minimum required performance of materials and their arrangement

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Regulatory compliant performance

The important aspects for

building design are:

•  Safety;

–  including structural and fire

safety;

•  Occupant health;

•  Occupant amenity; and

•  Sustainability

These are all

material-independent

Market acceptance

•  Performance level dictated by desire, impression, traditions or market whim

•  Requirements may not be linked to functionality or ability to supply

•  Market criteria can be regional and resilient, leading to considerable specification inertia

Medium Feature Standard:

Increased feature providing a surface with distinct natural appeal

Low Feature Select:

Straight & even grain with uniform texture

High Feature:

Distinct with a rich, lively & vibrant surface

Quality (fit-for-purpose)

appropriate and of a

necessary standard for

its intended use

•  Quality requirements

may be:

–  defined in a

BCA-referenced standard

–  established by market

expectation

•  Confidence in quality

can be key acceptance

requirement

Glulam made to AS 1328 Glued-laminated structural timber

Available

able to be used or obtained;

at someone's disposal

•  Items need to be available to be used

•  Specifiers and users need to:

–  Know what is available and what it can do

–  Be confident of regular and supported supply

Timber stock racks

Economic

requiring fewer resources or

costing less money

•  Economic construction

supplies the desired level of

performance at a system cost

comparable to or less than

alternatives

•  Specifiers and users need to:

–  Know that it is economic

–  Be confident of competitive

pricing

Class 3 hotel construction

Summary

•  Timber is natural, renewable, variable (anisotropic), hygroscopic, bio-degradable material

•  It is democratic, versatile in its use and has a high-strength to weight ratio

•  To be accepted, timber solutions must provide regulatory and market compliant performance

•  It can (and needs to) provide quality (fit-for-purpose) solutions, available to the building community, and economic when compared to alternative solutions

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