Wood and Timber

Question 1

How many cubic meters of tinder are harvested worldwide every year?

Answer 1

~1.6 billion m^3

Question 2

How much timber is used in the UK each year?

Answer 2

50 million m^3

Question 3

How much timber does the UK produce each year?

Answer 3

~16 million m^3

Question 4

How much of the UKs timber is imported?

Answer 4

66%

Question 5

What type of wood is used in construction, and where does it come from?

Answer 5

Softwood

From Scandinavia and the baltic states

Question 6

What type of wood is used for furniture and interior design and where does it come from?

Answer 6

Hardwood and it comes from Eastern and Western Europe and North America

Question 7

How is tropical wood used?

Answer 7

In marine construction and high value interiors

Question 8

What are some advantages of wood in construction?

Answer 8

• Excellent combination of physical properties
• High compressive and tensile strength
• Readily available
• Relatively low cost
• Good thermal properties
• Good durability in some conditions
• Predictable fire behaviour
• Sustainable material if harvested right
• compatible with other engineering materials
• Aesthetically pleasing

Question 9

What are some disadvantages of timber?

Answer 9

• Widely variable properties
• variability in performance
• properties vary in different directions
• contains inherent flaws
• significant waste from each tree
• durability can be poor under particularly wet conditions
• attacked by certain insects, bacteria, and fungi
• transport costs
• needs to be dry before use
• dimensional stability
• fire performance

Question 10

What makes wood a sustainable construction material?

Answer 10

• It is the only renewable construction material
• Low embodied energy consumption
• Low in use energy consumption due to low thermal conductivity
• High embodied carbon due to photosynthesis

Question 11

How much CO2 does a tree absorb through photosynthesis and how much oxygen do they produce in the same period?

Answer 11

1000kg CO2

727kg O2
per m^3 growth

Therefore young trees are better for the environment than old ones

Question 12

By using wood instead of another construction material how much CO2 is embodied?

Answer 12

2 tonnes per m^3

Question 13

How much more energy do concrete and steel use than timber strength for strength?

Answer 13

concrete uses 5x

steel 6x

Question 14

What organisation ensures sustainable forests?

Answer 14

The forest setwarship council (FSC)

Question 15

What does the FSC do?

Answer 15

combat illegal and unethical logging techniques as well as environmentally damaging logging

Question 16

How much of the wood consumed in Europe is from European forests?

Answer 16

over 90%

Question 17

Why is the European forest industry so good?

Answer 17

It plants more trees than it harvests

European forests grow by 3,500 square miles a year

Question 18

How much carbon is stored in European forests?

Answer 18

9.5 miillion tonnes

Question 19

How much of the weight of wood is carbohydrate?

Answer 19

70%

Question 20

What structure does glucose have?

Answer 20

ring

Question 21

What are glucose molecules linked by

Answer 21

alpha or beta linkages to form polysaccharides

Question 22

What does cellulose consist of?

Answer 22

Cellulose structures, joined by beta-1,4 bonds

Question 23

What part of wood does lignin make up?

Answer 23

The non biodegradable part

Question 24

What is the structure of lignn

Answer 24

A massive random polymer of phenylpropane alcohol

Question 25

What is the moisture content of wood when it is cut?

Answer 25

up to 85%

Question 26

How is wood dried?

Answer 26

Either by air drying or Kiln drying

Question 27

What is the structure of wood like?

Answer 27

On the very outside you have bark, consisting of the periderm (cork cambium and cork) and the living phloem Then you have the sapwood Then the heartwood

Question 28

What are the differences between heartwood and sapwood?

Answer 28

- colour - durability - permeability

Question 29

What is not different about heartwood and sapwood?

Answer 29

Strength

Question 30

How do you tell the difference between soft and hardwoods?

Answer 30

Softwoods come from coniferous trees, hardwoods come from deciduous trees

Question 31

What are key parts of the microstructure of wood?

Answer 31

- Multi-component - hygroscopic - anisctropic - inhomogeneous - Discontinuous - inelastic - fibrous - porous - biodegraddable - renewable

Question 32

What does SEM stand for?

Answer 32

Scannign electron microscopy

Question 33

What does the microstructure of hardwood resemble?

Answer 33

close packed drinking straws

Question 34

Why is are the properties of woods different in different directions?

Answer 34

Due to inherit flaws such as knots, wanes, growth rings and fissures

Question 35

What grain direction is strong in tension?

Answer 35

Along grain

Question 36

What grain direction is strong in compression?

Answer 36

Along grain

Question 37

What grain direction is resistant to shear?

Answer 37

across strain

Question 38

How does wood perform in bend strength testing?

Answer 38

like a fibre reinforced composite material with significatn toughness

Question 39

What decay mechanisms are present in wood?

Answer 39

Fungal decay | Dry and wet rot

Question 40

What moisture content is neeeded for decay to occur in wood

Answer 40

>25% | hence why wood is not good when in contact with soil

Question 41

What is the associated costs of insect infestation a year to the UK?

Answer 41

£900 million

Question 42

What types of insects cause damage to wwod?

Answer 42

``` Not as moisture dependent: Common furniture beetle Death watch beetle House longhorn Powderhpost beetles Forest longhorn beetles Pinhole borer Wood wasps ``` Marine Borers: Shipworm Gribble

Question 43

Name some structural timber composites

Answer 43

- Glulam - Orientated Strand-Board (OSB) - Laminated veneer Lumber (LVL) - Parallel strand lumber (PSL) - Laminated strand lumber (LSL) - Prefab I joists

Question 44

What are the benefits of structural timber composites?

Answer 44

They are sold as products Their properties are known The properties are product specific Design information is provided by technical approval documents

Question 45

What are other names for structural wood products?

Answer 45

- Engineered wood products - Engineered Lumber products - Structural composite lumber

Question 46

What are the benefits of glulam?

Answer 46

- Better structural properties - dimensional stability - large sizes - reduced wastage of timber resource - less material variablilty - aesthetic variety - utilization of material unuitable for conversion to sawn timber

Question 47

What wood species mostly makes up glulam?

Answer 47

European whitewood

Question 48

Usually how deep are the laminates in glulam?

Answer 48

45 mm

Question 49

What adhesive is used in glulam?

Answer 49

PRF phenol resorcinol formaldehyde

Question 50

Where does the higher class material go in glulam if inhomogeneous?

Answer 50

on the outside

Question 51

What is the mass of glulam?

Answer 51

500 kg m^-3

Question 52

What are some of the size/ shape benefits of glulam?

Answer 52

- standard straight cross sections - Curved and / or tapered - manufactured up to 45 m

Question 53

Where is glulam typically used?

Answer 53

Beams and columns Domes, curved roofs and arches footbridges

Question 54

Where is orientated strand lumber used?

Answer 54

Timber frame wall panels

Question 55

How is laminated venner lumber made?

Answer 55

Produced by bonding together veneers peeled from a log (~3mm thick) These long panels are cut into structural sized sections Veneers are orientated in common grain direction

Question 56

What is the maximum length currently available for laminated veneer lumber?

Answer 56

26m

Question 57

Where is laminated veneer lumber typicall used?

Answer 57

roof or floor beams in factory built housing | Flanges of I joists footbridges and bridge decking

Question 58

How are parallel strand lumber sections produced?

Answer 58

Long peeled veneers (2400mm) are coated with glue and layered using a heat and pressure quasi extrusion process to form long structural sized sections

Question 59

What are the benefits of I joists?

Answer 59

Strong, stiff, straight, light, long | Dimensionally stable, cost effective, easy to handle, use less timber material, quality assured

Question 60

How many new homes are made out of timber in the UK?

Answer 60

25%

Question 61

How many new homes in scotland have a timber frame?

Answer 61

3/4

Question 62

How much shorter is the construction time with timber?

Answer 62

30%

Question 63

How many days does it take to get a timber frame house weather proof

Answer 63

less than 5

Question 64

How much more wood is used than in an equivalent masonry home?

Answer 64

5-6m^3

Question 65

How many tonnes of CO2 are saved by every timber house?

Answer 65

4

Question 66

What other benefits to timber framed houses have?

Answer 66

reduced running costs

Question 67

What are the advantages of wood as an engineering material?

Answer 67

- Low energy content needed for preduction - Low cost of production - Wood is environmentally friendly material - wood is renewable - wood has very high specific strength - wood is low density, which makes it easier to transport - very low disposal costs - not electrically conductive - most are non-toxic - low thermal conductivity - not weakened by nails and screws - resistant to stress concentrations

Question 68

What are the main disadvantage of wood in construction?

Answer 68

- Large variability in properties between species - wood is dimensonally unstable - strength decreases when wet - time-dependent deformation such as creep and visco-elasticity - susceptible to termites, wood worms etc. - cannot be used at high temperatures - suscpetible to rot and disease - highly anistropic - Not particularly fire resistant