Transcript WOOD CONSTRUCTION

WOOD CONSTRUCTION
WOOD
Hardwood: deciduous
• Oak, maple, walnut
• fine carpentry
Softwood: 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