timber 1

Question 1

what are the 3 sub systems for timber?

Answer 1

1. Root system
2. Trunk
3. Crown

Question 2

what are the 3 characteristics of timber?

Answer 2

1. strength
2. Appearance
3. durability

Question 3

Name 4 natural defects of timber

Answer 3

1. Knots
2. Fungi
3. Cracks
4. overgrowth

Question 4

Name 3 types of Knots that are found

Answer 4

1. Live
2. Dead
3. Enclosed

Question 5

What are Knots?

Answer 5

Branches that become enclosed within growing trunk

Question 6

What are cracks?

Answer 6

Fissures which disrupt continuity of of timber

Question 7

3 types of cracks?

Answer 7

1. Star heat shake
2. cup/ring shake
3. Radial shake

Question 8

Defects of fungal decay are?

Answer 8

1. Dote

2. Punk

Question 9

What is dote?

Answer 9

White streaks/ patches
called pocket rot
LITTLE DETERIORATION

Question 10

What is punk?

Answer 10

Progressive decay, can cause softening

softening of centre- brittle heart, spongy heart, punky heart

Question 11

what causes blue stain?

Answer 11

Sap stain. they feed on sugars left over from sap

Question 12

what is reaction wood?

Answer 12

timber where one side is in compression

Question 13

what situations does reaction wood form in?

Answer 13

on slopes

in windy areas

Question 14

is reaction wood strong?

Answer 14

no. brittle and prone to shrinkage. Can distort

Question 15

defects of preparation of wood?

Answer 15

1. conversion

2. seasoning

Question 16

what is seasoning?

Answer 16

Drying of wood

Question 17

how can distortion occur if seasoning defect happens?

Answer 17

1. excessive drying
2. uneven drying
3. exposed to wind/ rain

Question 18

what is mechanical stress grading?

Answer 18

1. applying TRANVERSE load over successive short lengths
2. machine records MAX deflection, converts to mod of elasticity
3. compares relationship between stiffness and strength

Question 19

advantages over visual grading of mechanical stress grading?

Answer 19

1. non destructive
2. more reliable
3. lower factors of safety