Lecture 18

Question 1

How does wood change?

Answer 1

Wood shrinks across the grain not along the grain. Lumber cross section changes due to the relative humidity of air. Quarter sawn shrinks unifromly, flat sawn lumber cups, bows, or twists

Question 2

What is lumber surfacing done by?

Answer 2

Surfacing is done by high-speed planing machines

Question 3

What does lumber surfacing do?

Answer 3

Smoothes lumber, round off the edges, and makes it more square, removing some of the distortions that occurred during the seasoning process

Question 4

What is lumber that was surfaced before seasoning called?

Answer 4

S-GRN (surfaced green)

Question 5

Softwoods

Answer 5

Originating from north American forests, fast growing, plentiful, inexpensive, soft, easily workable

Question 6

Hardwoods

Answer 6

Harvested from around the world, slower, denser, more expensive

Question 7

Three classifications of softwood lumber

Answer 7

Board lumber (or boards), dimension lumber, and timbers

Question 8

Most commonly used lumber

Answer 8

2x (two-by)

Question 9

Dimension lumber is available in lengths of..?

Answer 9

8ft, 10ft, 12ft, and so on up to 28ft

Question 10

Lumbers strength and appearance

Answer 10

Not same degree of uniformity as steel or concrete

When axis runs parallel to grain, stronger.

Question 11

What reduces strength in lumber?

Answer 11

Knot in a member, if grain doesnt run parallel to the axis

Question 12

Knots in members

Answer 12

Weaker, stronger when near longitudinal axis

Question 13

What is a check?

Answer 13

A check is a seperation of wood fibers along the rays (perpendicular to growth rings)

Question 14

What is a shake?

Answer 14

A separation of wood fibers along the growth rings

Question 15

What is a split?

Answer 15

A split occurs at the ends of a member and is a complete separation of wood fibers through the entire end

Question 16

What is a wane?

Answer 16

A wane is the absence of wood or the presence of bark at the corner or the edge of a piece that results from the sawing process

Question 17

Lumber grading

Answer 17

Each piece of lumber used for structural framing is graded and stamped

Question 18

What do higher structural grades mean?

Answer 18

Fewer defects and when left exposed are generally also more attractive

Question 19

Appearance grading

Answer 19

Appearance grading is always performed visually

Question 20

What is bio-deterioration?

Answer 20

Cause by living organisms that use wood as food

Question 21

What are the two groups of organisms that consume wood?

Answer 21

Fungi (fungal decay, decay of wood or rotting)

Insects (termites, water based wood eating insects, and carpenter ants)

Question 22

Termite control

Answer 22

For wood members not buried in the ground, maintain distance between ground, soil barrier with chemical soil treatment, natural decay resistant, termite shield, inspection and remediation

Question 23

What is preservative treated lumber?

Answer 23

Most effective and commonly used method of achieving termite protection. Must be toxic to organisms but non-damaging to wood.

Question 24

Three types of preservatives to protect lumber

Answer 24

Creosote, oil-borne preservatives, waterborne preservatives

Question 25

What is FRTW

Answer 25

Fire-retardant treated wood is lumber of plywood that has been pressure treated with chemicals that retard the development of fire.