WOOD CONSTRUCTION

WOOD

Hardwood: deciduous• Oak, maple, walnut

• fine carpentrySoftwood: coniferous (cone bearing)

• Pine, spruce, fir

• outdoor

WOOD DECAY

Decay requires:• Food (wood)• Moisture

MOISTURE CONTROL

• Susceptible wood should be 8" above soil

• 5% grade from house out 10'• Downspouts 10' away from house

MOISTURE CONTROL

• Shrubs should be 5' + 1/2 the mature diameter away from house

MOISTURE CONTROL

• Crawlspace crowned and covered with plastic

NATURALLY DECAY RESISTANT WOOD

CEDAR• Fragrant• Structurally weak

NATURALLY DECAY RESISTANT WOOD

CEDAR• Commonly 1x dimensions

NATURALLY DECAY RESISTANT WOOD

CYPRESS• Good structural• Commonly 1x dimensions

NATURALLY DECAY RESISTANT WOOD

REDWOOD• Natural red color• Good structural• Expensive • Heartwood most resistant (versus

sapwood)

NATURALLY DECAY RESISTANT WOOD

COMPOSITE WOOD• Hardwood sawdust and reclaimed

plastic• Very durable, good longevity• No splinters• Expensive

NATURALLY DECAY RESISTANT WOOD

IPE (EE-pay)• Tropical wood• Extremely dense (drill holes for nails)• Decay and fire resistant• Does not float

PRESSURE TREATED WOOD

• Wood susceptible to decay• Forcing chemical preservatives into

wood under high pressure• Copper-containing (ACQ)

• Safest available• Arsenicals (Not common anymore)

• Chromated copper arsenate (CCA)• Health concerns

• Creasote• Railroad ties

PRESSURE TREATED WOOD

• Concentration ratings•0.40 -- ground contact (pounds per

cubic foot)

PRESSURE TREATED WOOD

SOUTHERN YELLOW PINE• Structurally strong• Dense• Very susceptible to warping and

shrinkage

PRESSURE TREATED WOOD

• Do not burn, toxic fumes• Avoid prolonged inhalation of

sawdust• Wash after prolonged exposure

WOOD SIZE

• Nominal size: actual dimension of wood at the cutting mill

• Actual size: after milling (shrinkage and planing)• 1" and less: 1/4"• 2" to 6": 1/2"• 8" and above: 3/4"

COMMON DIMENSIONS

• Lengths: 6', 8', 10'...• Thickness and width• 2" bys (2x4, 2x6, 2x8, 2x10 or 2x12)• 4" x 4" or 4" x 6"• 6" x 6"

COMMON DIMENSIONS

• PLYWOOD: thin layers of wood glued together

• 4'x8' sheets• Thickness: 1/4", 1/2", 3/4", 5/8"...• Exterior grade

GRADING: QUALITY

• SELECT and NO. 1 high grades•No. 2 commonly used

GRADING: MOISTURE

• Moisture content• Dried to less

than 19% moisture to avoid rot (s-dry)

• >19% is green wood (s-grn)

GRADING: OTHER

• Mill• Grading

association• Species

GRAIN

• Growth rings created by different growth rates throughout year

• Springwood: lighter band an softer• Summerwood: dark and dense• Fine grain: rings close together (slow

grower)• Coarse grain: rings far apart

HEARTWOOD• Inner, inactive portion of trunk• Plugged off and high resistance to rot

SAPWOOD• Outer layer still active• Not as decay resistant or structurally

sound

QUALITY

• Warping, bowing, cupping, splitting

Knots• Result of limbs• Reduces strength and workability

STORAGE

• Off ground• Stacked neatly • Covered and out of direct sun