Wood

Question 1

Advantages of using wood as a building material?

Answer 1

• Beauty
• Availability
• Cost
• Production
• Biodegradable
• Sustainable
  etc

Question 2

What is Endogenous?

Answer 2

• Intertwined growth
• Bamboo, palms etc
• Strong
• Lightweight
• Not really used in engineering (dev countries)

Question 3

What is Exogenous?

Answer 3

• Outward growth (most other trees)
• Fibres grow from centre outwards by added concentric
  layers (annual rings)

Question 4

What is Hardwood?

Answer 4

Board leaf tree

Question 5

What is Softwood?

Answer 5

• Conifevous trees

- Needle like foliage and cones

Question 6

What is Deciduois?

Answer 6

• Loose foliage in autumn
• Ash, oak, maple trees
• Doe inc larch which is a conifer

Question 7

Radiata facts

Answer 7

= 90% of sawn lumber

• From california
• Light in colour
• Low durability but easily treated
• Moderately strong

Question 8

Douglas Fir facts

Answer 8

= 5% of sawn lumber

• From western USA
• Pink/brown in colour
• More durable than radiata

Question 9

Rimu facts

Answer 9

• Commercially available in small quantities
• NZ Native
• Brown in colour
• Medium density
• Reasonably strong

Question 10

Forestry Management Steps include?

Answer 10

1) Planting (1000 seedings per hectare)
2) Thinning (removing trees, after thinning 300-600 trees remain per hect, allows for better growth)
3) Pruning (cutting off branches on young trees to prevent knots)

Question 11

Macrostructure in order from outer layer in middle.

Hint - 5 main layers

Answer 11

1) Outerbark
2) Innerbark
3) Cambium cell layer
4) Sapwood
5) Heartwood

Question 12

What is bark for?

Answer 12

Protection as it is dense and rough.

Question 13

Innerbark purpose?

Answer 13

Transport sap from leaves to growing parts of tree.

Question 14

Cambium purpose?

Answer 14

Forms new wood bark.

- As they grow they form a ring of new cells varying in width 0.02-0.05mm depending on rate of growth.

Question 15

Sapwood use?

Answer 15

about 1/3 radium of log

• Takes moisture from roots
• Stores food for growth

Question 16

What is Heartwood?

Answer 16

Inner core of tree, non living cells, more resistant to decay.

Question 17

What is the pith?

Answer 17

• Centre of trunk
• Small cylinder of primary tissue
• New shoot of the growing tip of the tree

Question 18

What is Latewood (summer wood)?

Answer 18

• Forms later in growing season
• Cell growth slow
• Smaller diameter, thicker cell walls
• Darker in colour

Question 19

What is Earlywood (spring wood)?

Answer 19

• Forms during rapid growth
• Cells have large diameter, thin cell walls
• Light in colour

Question 20

Variability in wood

Answer 20

• Number of species (30,000)
• Composite material, diff components, very diff properties
• Imperfections, knots etc
• Anisotropic
• Properties of wood are highly sensitive to moisture condition