Timber Technology

Question 1

What is the centre of the tree called?

Answer 1

The Pith. It is not very good wood

Question 2

Dead Part of the three trunk?

Answer 2

Heartwood. Protects from fungal

Question 3

What is Sap Wood?

Answer 3

Nutrient Part of the tree. Living

Question 4

Two Main Classes of Wood Species?

Answer 4

Softwood and Hardwood

Question 5

Soft Wood Characteristics?

Answer 5

• Softer
• Easier to Handle
• Does not split when nailed
• Popular as sawn Timber

Question 6

Softwood Trees?

Answer 6

Evergreen Trees such as Pine and Fir

Question 7

Hardwood Trees?

Answer 7

Deciduous trees such as:

• Mahogany
• Oak
• Maple
• Gum Trees
• Walnut used in high quality furniture

Question 8

Which direction is shrinkage least likely to occur?

Answer 8

Longitudinal

Question 9

Two types of shrinkage?

Answer 9

Tangential - Results in timber stressing

Radial -

Question 10

How Does Cupping occur?

Answer 10

When grains of wood are at angles

Question 11

What percent mark does shrinkage occur?

Answer 11

25%

Question 12

How is wood dried/seasoned?

Answer 12

Kiln drying:

• Steam
• LPG Gas
• Solar
• Off cuts

Air drying

Other:

• Chemical
• Microwave

Question 13

What is EMC?

Answer 13

Equilibrium Moisture Content

Question 14

What is external/inland EMC?

Answer 14

15%

Question 15

Describe EMC flows?

Answer 15

• Wet atm/Dry Wood = Moisture moves to wood
• Dry Atm/Wet Wood = Moisture moves from wood
• Wood at EMC = No moisture movement to/from wood

Question 16

Benefits of Seasoning?

Answer 16

• Better Resistance to decay by fungi
• Improved resistance to weathering
• Stale in dimension; Creep Alleviated; Protective coating adheres better
• Strength Improves

Question 17

What are the timber products?

Answer 17

• Sawn Timber
• Laminated Veneer Lumber (LVL)
• Plywood
• Hardboard
• Glulam

Question 18

Sawn Timber Examples. (Probably won’t examine)

Answer 18

• Stump: Foundation of houses
• Bearer: Bears load of house
• Floor Joist: Prevent bearer from bending
• Stud: Wall Timber

Question 19

How is LVL made?

Answer 19

Timber is sawn into thin piles (Laminates) along the direction of the fibre

Question 20

What is Plywood?

Answer 20

Similar to LVC but the fibres in adjacent sheets are orthogonal directions (Criss cross)

Question 21

Difference between plywood and LVL?

Answer 21

1. Alternative directions in plywood

2. Plywood is a sheet product whereas LVL is a beam

Question 22

What is hardboard?

Answer 22

Hardboard is a compressed composite board

Question 23

What is Medium Density Fibreboard (MDF)?

Answer 23

MDF is a type of hardboard which is made from wood fibres glued under heat and pressure

Question 24

What is Glulam (Glue Laminated Timber)?

Answer 24

Plain saw timber bits glues together, enabling curved and tapered features to be achieved

Question 25

What is cross laminated timber?

Answer 25

Plain sawn timber put into a panel. They are in layers. Sticking together timber. Used for big buildings. Layered in different directions. Alternating pattern makes a plate. We want stiffness in multiple directions.

Question 26

Sorting timber classifications?

Answer 26

Appearance grading and Structural Grading

Question 27

Structural Gradings Methods?

Answer 27

Visual stress grading Machine Stress Grading Proof Grading Quality Control

Question 28

Most common timber grade?

Answer 28

F7

Question 29

Visual Stress Grading Characteristics?

Answer 29

- Size of knots relative to specimen - Borer Holes - Termite Galleries

Question 30

Why are knots problems?

Answer 30

They change grain direction. This can cause localised weak spots

Question 31

Durability Issues?

Answer 31

- Weathering - Decay with Fungi - Termites and bores - Countering Measures

Question 32

Weathering issues?

Answer 32

- Bleaching and erosion of surface - Loosening of timbers - Opening of cracks - End of lumbers most vulnerable - Metal connectors are prone to corrosion

Question 33

Fungi occurs at:

Answer 33

- M.C >20% - Presence of oxygen - Ideal at 25-40deg C - Sapwood at periphery is more vulnerable

Question 34

Termite and bores facts:

Answer 34

- Hazard level increases with latitude | - End of member is most vulnerable to attack

Question 35

Countering Measures:

Answer 35

- Sheltering and protective - Isolation from ground - Moisture control - Use durable timber specie - Chemical treatment

Question 36

Difference between glulam and LVL?

Answer 36

Glulam uses plain sawn timber stuck together with reasonable thickness whereas LVL uses thicker ones stuck together