WOOD

Question 0

What is the difference between cellulose and lignin?

Answer 0

Lignin is the soft substance that bonds the tough cellulose

Question 1

Tell me about the different components of a living tree.

Answer 1

The pith is the innermost section of the heartwood, from the first year of growth. The heartwood is the inner section that is no longer living. The sapwood is the thick layer of living cells that pump nutrients up towards the leaves. A very fit in there called cambium creates new bark cells towards the outside and new wood cells going inward.

Question 2

Which are larger and less dense, Springwood or earlywood cells… Or Summerwood or latewood cells?

Answer 2

Springwood/earlywood because the air is cool, groundwater plentiful, conditions that favor rapid growth

Question 3

What is the basic difference between softwoods and hardwoods?

Answer 3

Softwoods are from coniferous trees, I do they have a relatively simple microstructure (large longitudinal cells called tree kids with a few radial sells called rays to store and transfer nutrients).

Hardwoods are from Broadleaf trees, more complex in structure, having many more rays and two kinds of longitudinal cells: small diameter fibers and large diameter vessels/pores, transporting sap.

Question 4

Most of the lumber used for building framing today comes from…

Answer 4

Softwoods

Question 5

What is the lumber recovery factor?

Answer 5

Percentage of wood products produced from a cubic meter of log

Question 6

How many BTU does solid lumber embody per pound? What has a higher embodied energy?

Answer 6

1000 to 3000 BTU per pound. Manufactured wood products are from 3000 to 7500 BTU per pound.

Question 7

Would it does not have the lowest embodied energy compared to other structural materials, but …

Answer 7

… when used in small buildings wood structures usually have a lower overall embodied energy

Question 8

What is the first thing you cut a log with to make lumber?

Answer 8

A headsaw

Question 9

What is the difference between plainsawn and quartersawn?

Answer 9

Plainsawn is wood that is sliced straight, and therefore also with a variety of flat patterns. Greater economy than…

Quartersawn. Sliced diagonally, four ways. This produces edge grain or vertical grain lumber, more consistent. Less warping.

Question 10

Water makes up from 30% to as much as 300% of the dry weight of wood. What are the different types of water in wood?

Answer 10

Free water is held in the cavities of the cells. This water leaves first.

Found water, making up 26 to 32% of remaining moisture, is held within the cellulose of the cell walls. When this water leaves the wood shrinks, and stiffness and strength increase.

Question 11

What is the definition of seasoned wood?

Answer 11

Wood but has been brought down to a moisture content of 19% or less

Question 12

MC 15 would have the moisture content to 15%. But it doesn’t make any sense to bring it down below 13%, why?

Answer 12

Because the wood will take on the moisture of the environment anyway. For interior carpentry you can bring it down lower, to moisture content expected in the completed building.

Question 13

What is the equilibrium moisture content?

Answer 13

The expected moisture in the completed conditioned building

Question 14

Why is kiln drying preferred to air drying?

Answer 14

It can be done faster, producing more uniform wood

Question 15

What causes checks in wood?

Answer 15

Tangential shrinkage being greater than radial shrinkage

Question 16

Why do crooking, bowing, twisting, and cupping occur?

Answer 16

Nonuniform shrinkage

Question 17

Compare defect-free wood to steel on a strength per-unit of weight basis.

Answer 17

They are equal. But since lumber usually has defects it is inferior to steal in strength by weight.

Question 18

How does the strength of wood in tension compare to the strength of wood in compression?

Answer 18

It’s roughly half in tension. 300 to 1000 psi versus 600 to 1700 psi

Question 19

If a piece of lumber is less than 2 inches in nominal thickness it is called a

Answer 19

Board

Question 20

If a piece of lumber is between 2 and 4 inches in nominal thickness it is called

Answer 20

Dimension lumber

Question 21

If a piece of lumber is five or more nominal inches in thickness it is called

Answer 21

A timber

Question 22

What is the unit of price for lumber?

Answer 22

The board foot

Question 23

Name two improvements on the basic glulam Beam.

Answer 23

Hybrid glulam Beam. Uses composite laminated veneer on the top and bottom - 20% stronger and 15% stiffer.

FRP reinforced glulam. Uses a thin strip of high-strength fiber reinforced plastic between the first and second limitations nearest the edge of the beam. You can save 25 to 40% in the volume of wood.

Question 24

What is the difference between levitated strand lumber (LSL) and oriented strand lumber (OSL)? What are two others?

Answer 24

The wood strands in LSL are longer

Laminated veneer lumber (LVL) looks like plywood without cross bands

Parallel strand lumber PSL looks like LFL and OSL but more uniformly parallel

Question 25

What is wood – plastic composite usually used for?

Answer 25

Exterior decking, railing systems, trim

Question 26

When does lumber become plastic lumber?

Answer 26

When it is at least 50% plastic

Question 27

Structural grade plastic lumber is usually made from… which makes it…

Answer 27

High density polyethylene and which is reinforced with glass fibers … At Least as strong as conventional solid wood but lacking some other useful qualities

Question 28

What are composite panels?

Answer 28

To face veneers bonded over a core of reconstituted would… Sounds like regurgitated wood

Question 29

What is particleboard?

Answer 29

It has a smaller particles size than OSB

Question 30

Why use a medium – density overlay or a high – density overlay?

Answer 30

Where plywood needs to be especially smooth

Question 31

What is a flitch?

Answer 31

And alternative to rotary slicing, giving it more interesting veneer… Can also be arranged to produce symmetrical grain patterns

Question 32

What is A-B plywood?

Answer 32

Grade a veneer on one side, grade B veneer on the other

Question 33

What is creosote?

Answer 33

Oily derivative used to treat wood in engineering structures… Odorous, toxic, and unpaintable… Unsuitable for most building construction purposes

Question 34

What is pressure treated wood?

Answer 34

This actually refers usually to preservative treated wood …. Because long-lasting protection can only be accomplished by pressure impregnation driving preservative chemicals deeply into the fibers

Question 35

What is a pro and a con of incising wood?

Answer 35

It helps would absorb preservative chemicals, but it’s slightly lowers the structural capacity

Question 36

The hardwood of some species is naturally decay resistant. What are some of these species?

Answer 36

Redwood, cedar, black locust, black black walnut

Question 37

What is the most common material used in wood preservatives?

Answer 37

Copper … Therefore corrosive to many medals

Question 38

What do you measure the size of a nail in?

Answer 38

Pennies

Question 39

What are lag screws?

Answer 39

For heavy structural connections, with square or hexagonal heads, driven with a wrench rather than a screwdriver

Question 40

Main reason to use a washer with the bolt

Answer 40

Just tributes the force over a greater area of wood

Question 41

What does a split ring do?

Answer 41

Like a washer, it distributes load over a greater area of wood. You route out to circles in heavy timber and insert in the middle of the connection a split ring where the bolt will be fastened

Question 42

What is a SIP?

Answer 42

Structural insulated panel, two sheets of plywood or OSB joined firmly by a stiff plastic foam core

Question 43

What kind of pre-fabricated panel functions structurally like SIP?

Answer 43

Stressed-skin panel, which has two layers of plywood bonded by adhesive to the frame