WOOD! What is wood? An organic, natural composite of cellulose fibres A living structure combining strength & flexibility Contains WATER, even when dried,

WOOD!What is wood?

• An organic, natural composite of cellulose fibres • A living structure combining strength & flexibility

• Contains WATER, even when dried, making it pliable.• Weight for weight has the best engineering properties

of any material• Excellent insulator compared to metal, plastic and

concrete

Types of Timber• SoftwoodComes from EVERGREEN trees with needles. Typically grows quickly and in colder climates making it relativelycheap to buy.

• HardwoodComes from DECIDUOUS trees which grow slowly in warmer climates making it more expensive. Is denserthan softwood with a tighter grain.

The terms soft and hardwood are misleading as hardwoods are not necessarily hard or softwoods soft. Balsa (a hardwood) is actually softer than most softwoods. Though evergreens do tend to be less dense.

Types of SOFTWOOD Pine

Pale yellow with brown streaksand knots.• CHEAP• LIGHT

• QUITE STRONG• DURABLE

Cedar

Pale red and fragrant with a uniform,straight grain.• DURABLE

• NATURAL RESISTANCE TO ROT• EASY TO WORK

• LIGHT•GOOD INSULATOR

Types of HARDWOODTeak

Yellow/dark brown with a tight grain and high natural oil content.

• STRONG•DURABLE

• CURVES WELL / PLIABLE• NATURAL RESISTANCE TO RAIN

Mahogany

Pink/reddish brown with an attractive, interlocking grain.

• FAIRLY STRONG•ATTRACTIVE•DURABLE•EXPENSIVE

Oak

Light to medium brown with an open grain.

• STRONG•HARD• TOUGH•HEAVY• POROUS

Ash

Pale, light golden brown with an open grain.• FLEXIBLE• TOUGH•DURABLE

• EASY TO WORK

Beech

White – pinky brown with a close grain.• HARD• STRONG

• WARPS EASILY• TOUGH

• SUSCEPTABLE TO SHRINKAGE

Elm

Light to medium brown with an interlocking grain.

• PLIANT / BENDS WELL•TOUGH

• RESISTS SPLITTING• DURABLE IN WATER

• RESISTS DECAY WHEN WET

Types of Manufactured BoardPLYWOOD

Layers of thin wood sheets glued together at 90 degree angles to

each other. Often veneered.• STRONG IN RATIO TO WEIGHT•PLIABLE / CAN BE BENT• RESISTANT TO SPLITTING,

WARPING

BLOCKBOARD

Strips of softwood between 7-25mm thick are glued together side by sideand sandwiched between 2 layers of

veneer.• CHEAP• STRONG

• NOT SUITABLE FOR OUTDOOR USE

CHIPBOARD

Small wood particles mixed together with glue, heated and pressed in to

sheets. Usually plastic veneered.• VERY CHEAP

• CAN BE MADE FIRE RESISTANT• NOT VERY STRONG

• ABSORBS WATER AND SWELLS•RESISTANT TO WARPING (IF DRY)

MDF – Medim Density Fibreboard

Softwood waste is broken down into tiny fibres, mixed with urea

formaldehyde, heated and compressed into panels. Often veneered.

• CHEAP•DOESN’T WARP WHEN DAMP

• EASILY MACHINED• CAN BE MADE FIRE OR WATER

RESISTANT

HARDBOARD

Similar to MDF but denser. Made from compressed, glued fibres. Has one smooth side and one textured.

• CHEAP•EASY TO WORK

•POOR RESISTANCE TO MOISTURE• DOES NOT SPLIT OR CRACK

Which wood for

which purpose ?

TEAK Resists moisturePliable/curves well Durable

ELM Resists decay

Durable in waterTough

ASHEasy to work

FlexibleTough

Quiz time!

What wood mightthis be made of?

PLYWOOD!

And these?

Mahogany Oak

Or these?

MDF Pine

Finishes

• Sanding • Planing

Finishes

• Varnishing • Staining

Finishes

• Bleaching • Waxing

Finishes

• Oiling • Distressing

Finishes

• Lacquering

Health and Safety

• Wood manufacturing has one of the highest accident rates in the industry (www.hse.gov.uk)

• Wood dust can create health problems if a person inhales it or is exposed to it over a long period of time

• Dust/chippings can get in eyes• Wood dust can be slippery

Health and Safety

• Can get splinters if wood is untreated• Wood can be quite heavy• Machinery is dangerous eg. Saws, drills• Electrical equipment can break or be faulty• Noise of some machinery can cause heath

problems after long exposure• Fire risk – both wood/wood dust and the

products that treat it e.g varnish, paint

Sustainability

• Wood regarded as sustainable material• Grows naturally• Renewable• Uses CO₂ that humans create burning fossil

fuels, breathing etc.

Sustainability

• LCA (Life Cycle Assessment) method rates wood highly in sustainability.

• Evaluates materials of course of their life.

Sustainability

• Wood is good for environment in terms of:Global warming potentialResource useEmbodied energyAir pollutionWater pollution

Sustainability

• Global warming potentialStores CO₂Uses it as energyLower energy usage than in making of plastic and metal

Sustainability

• Resource useResource is renewableUsually easily recyclable/reusableDurable/long term

Sustainability

• Embodied energySum of all energy used to produce woodLower than other materials such as plastic and metalFrom raw material extraction, transport, manufacture, assembly, installation through to dis-assembly, deconstruction and decomposition

Sustainability

• Air pollutionWhen wood is living tree good for air pollutionExtraction and construction is lower than most resourcesOnly bad for air pollution when burned

Sustainability

• Water pollutionLow level pollution concerning wood and waterRated against other resources

Recycling

Pros Environmentally

friendly Raises awareness of

deforestation Saves landfill space If can be used in place

of plastic/metal, saves non renewable sources

Cons Recycled wood costs

less, but recycling costs high and time consuming

Demolition becomes more time consuming and complicated

Not well established trade

Recycling

• Wood can be recycled in different waysBecome fuelFlooring/deckingBeamsMulch

• Can either be broken down (fuel/mulch) or kept in original condition and refinished (beams/flooring)

By Ellie, Laura and Sophie