UNIT 5 -Construction Lumber

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UNIT 5 -Construction Lumber
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Construction Lumber
Hardwood
Softwood
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Hardwood
Deciduous Trees such as Oak, Locust,
Maple. Rarely used in Landscape Construction,
because of checking, splitting, and
discoloration. Less resistance to rot, due to
lower levels of oils and resins. Some
exceptions are Teak, Black Locust, Cypress. Oak
is often used as railroad ties then coated with
creosote as a preservative.
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Softwood
Coniferous Trees such as Yellow Pine, Douglas
Fir, Cedar, Redwood. Widely used in Landscape
Construction, because of their softer
qualities. Softwoods are easier to machine and
paint. Resistance to rot, due to higher levels of
oils and resins.
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Softwood Types
Cedars Weakest softwood, easy to machine, does
not hold nails well, Rot resistant and weathers
to natural gray, Readily available and moderately
expensive. Douglas Fir Moderately hard,
difficult to work with, does not take paints
well, moderate rot resistance, requires stain or
preservative, Readily available and moderately
expensive.
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Softwood Types
Southern Yellow Pine Hard dense. Strongest
wood used. Hard to machine, does not take stain
and paint well. Will shrink and warp due to
excess moisture and oils. Treated to resist rot,
can be stained. Widely available in many sizes
and shapes. Least expensive. Redwood Strong and
moderately dense. Most versatile, easiest to work
with and stain. Highly rot resistant, Weathers to
uniform gray. Most difficult to find and most
expensive.
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Chromated Copper Arsenate

• Saw, sand, and machine CCA-treated wood outdoors,
  when possible. Wear a dust mask, goggles, and
  gloves.
• Clean up all sawdust, scraps, and other
  construction debris thoroughly and dispose of in
  the trash (i.e., municipal solid waste).
• Do not compost or mulch sawdust or remnants from
  CCA-treated wood.
• Do not burn CCA-treated wood, as toxic chemicals
  may be released as part of the smoke and ashes.
• After working with the wood, wash all exposed
  areas of your body, especially the hands,
  thoroughly with soap and water.
• Wash your work clothes separately from other
  household clothing before wearing them again.

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Wood Alternatives
Plastic lumber is an increasingly popular
building material. Plastic lumber, which is most
frequently composed of high density polyethylene
(HDPE), does not release hazardous materials into
the ground. An additional benefit of using this
material is that it is often manufactured with
recycled plastic. Therefore, using plastic lumber
conserves natural resources. In addition, plastic
lumber usually requires less maintenance.
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Wood Alternatives
Composite lumber - Wood and plastic combined into
one lumber product is called composite lumber.
Wood/plastic composites generally exhibit low
moisture absorption and high resistance to decay,
insect, and UV ray damage. The wood component
provides the composite with greater dimensional
stability than plastic lumber, but not as much as
wooden lumber. Like plastic-only lumber,
wood/plastic composite lumber is often made with
recycled materials.
Alternatives to CCA
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Lumber Grades
Select Grade A Best clear Lumber Grade B
Blemish Free Grade C Small Defects Grade D -
Utility ( knots under ½)
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Lumber Grades
Common No. 1 Sound Knots No. 2 Loose
Knots No. 3 Large Knots, Bark edges No. 4 5
Poorest wood quality
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Plain or Quarter Sawn??
In Plain sawing the cut is made tangent to the
growth rings. This method yields the maximum
number of cuttings with minimal waste. Wood cut
in this manner is more prone to warp.
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Plain or Quarter Sawn??
In quarter-sawing the cut is made radially to the
annual rings. The log is cut into quarters, then
towards the center. This method is more
wasteful, therefore more expensive, but is less
distorted by warping.
It also reduces checking and splitting.
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Rough Cut Lumber
Rough cut lumber is defined as its name implies.
Rough cutting is the first machining of a log
into nominal dimensions. EX 2X4, Its appearance
is actually ROUGH in so that it is not suitable
in landscape construction for aesthetic reasons.
It is also not recommended for exterior
applications, because it will not take paints and
stains well and will have little rot resistance.
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Dimensional Lumber
Dimensional lumber is Rough cut lumber which has
been surfaced on all sides. This surfacing
removes part of the lumber making it smaller than
its original size. Typically this surfacing
removes about ¼ per side. This makes
dimensional lumber about ½ smaller in width and
height. EX. 2X4 is actually 1.5X3.5