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Chapter 2 Lumber Carpentry First Canadian Edition
© 2009 Nelson Education Ltd.
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Manufacture of Lumber Logs arrive at a sawmill and the bark is removed
A bandsaw cuts the log into planks A series of saws are used to slice, edge and trim The wood is cut to various dimensions Wood is stacked for sticking and then dried Carpentry First Canadian Edition © 2009 Nelson Education Ltd.
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Carpentry First Canadian Edition © 2009 Nelson Education Ltd.
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Manufacture of Lumber (cont.)
Lumber is standardized and shipped Measuring terms Long, narrow surface is the edge Long, wide surface is its side The extremities are called ends Distance across the edge is the thickness Distance across the side is the width Distance from end to end is the length Carpentry First Canadian Edition © 2009 Nelson Education Ltd.
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Carpentry First Canadian Edition © 2009 Nelson Education Ltd.
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Plain-Sawed Lumber Common way of cutting lumber
Log is cut tangent to annular rings This produces a distinctive grain Least expensive, producing greater widths Shrinks during drying, warps easily Slash-sawed lumber Carpentry First Canadian Edition © 2009 Nelson Education Ltd.
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Carpentry First Canadian Edition © 2009 Nelson Education Ltd.
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Quarter-Sawed Lumber Produces pieces with annular rings at right angles Shrinks less, warps less easily High durability Frequently used for flooring Also called vertical-grain or edge-grain Carpentry First Canadian Edition © 2009 Nelson Education Ltd.
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Carpentry First Canadian Edition © 2009 Nelson Education Ltd.
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Combination Sawing Using technology to cut a log in a way that wastes the least amount and takes a short amount of time Carpentry First Canadian Edition © 2009 Nelson Education Ltd.
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Carpentry First Canadian Edition © 2009 Nelson Education Ltd.
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Moisture Content and Shrinkage
Green Lumber Newly cut wood that hasn’t dried and will shrink Should not be used in construction As it shrinks, it usually warps Subject to decay due to its moisture content Seasoned wood should be protected from moisture Carpentry First Canadian Edition © 2009 Nelson Education Ltd.
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Moisture Content (MC) Expressed as a percentage
Determined by the weight before and after oven drying and dividing that number by the dry weight Lumber used for framing and exterior should have an MC that does not exceed 19% Carpentry First Canadian Edition © 2009 Nelson Education Ltd.
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Carpentry First Canadian Edition © 2009 Nelson Education Ltd.
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Carpentry First Canadian Edition © 2009 Nelson Education Ltd.
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Carpentry First Canadian Edition © 2009 Nelson Education Ltd.
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Carpentry First Canadian Edition © 2009 Nelson Education Ltd.
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Drying Lumber Can be air dried and stacked in piles with spacers
Can be stacked and dried in huge ovens called kilns that provide controlled temps, humidity and air circulation Kiln drying takes less time but is more costly Carpentry First Canadian Edition © 2009 Nelson Education Ltd.
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Carpentry First Canadian Edition © 2009 Nelson Education Ltd.
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Carpentry First Canadian Edition © 2009 Nelson Education Ltd.
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Drying Lumber (cont.) Recommended MC for exterior finish lumber is 12%
Lumber with 8-10% MC is for interior trim and cabinet work Moisture meters are used to measure moisture content Carpentry First Canadian Edition © 2009 Nelson Education Ltd.
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Carpentry First Canadian Edition © 2009 Nelson Education Ltd.
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Lumber Storage Store lumber so it is protected from moisture and other hazards Keep lumber off the ground Cover with a tarp, leaving room for air circulation Carpentry First Canadian Edition © 2009 Nelson Education Ltd.
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Lumber Defects A defect is any fault that detracts from its appearance
Warps are caused by drying lumber too fast, poor storage, or surfacing lumber before it is dry Splits (called checks) are caused by uneven drying Cracks (called shakes) run between and parallel to annular rings Carpentry First Canadian Edition © 2009 Nelson Education Ltd.
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Carpentry First Canadian Edition © 2009 Nelson Education Ltd.
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Lumber Defects (cont.) Lumber with a lot of juvenile wood can warp or twist Knots are cross-sections of branches in the trunk of the tree Pitch pockets are small cavities holding pitch Wane is bark on the edge of lumber Pecky wood has small grooves through the grain Carpentry First Canadian Edition © 2009 Nelson Education Ltd.
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Carpentry First Canadian Edition © 2009 Nelson Education Ltd.
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Lumber Grades and Sizes
Largest manufacturer of softwood is Western Wood Products Association (WWPA) Three categories include: Boards–under 2 inches thick Dimension–2 to 4 inches thick Timbers–5 inches and thicker Carpentry First Canadian Edition © 2009 Nelson Education Ltd.
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Lumber Grades Hardwood grades established by the National Hardwood Lumber Association Firsts and seconds (FAS) is the best grade Each piece must be at least 6” wide by 8’ long Next best grade is called Select (4”x6’) No. 1 common grade allows narrower widths by shorter lengths Carpentry First Canadian Edition © 2009 Nelson Education Ltd.
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Carpentry First Canadian Edition © 2009 Nelson Education Ltd.
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Lumber Sizes Rough lumber directly from the sawmill is close to nominal size Planing reduces the thickness and width to standard and uniform sizes Nominal size (what the piece is called, for example a 2x4) is not actual size (1½ x 3½) Carpentry First Canadian Edition © 2009 Nelson Education Ltd.
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Lumber Sizes (cont.) Lumber sizes are indicated by a series of numbers. Thickness″ × Width″ × Length′ For example, 1″ × 10″ × 12′ (One inch thick × 10 inches wide and 12 feet long) Carpentry First Canadian Edition © 2009 Nelson Education Ltd.
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Lumber Names Three general types: 1x6 2x6 4x6 e.g. 1x6 e.g. 2x6
Boards – 1 inch or less in thickness e.g. 1x6 1x6 2x6 Dimension Lumber – 2 inches in thickness e.g. 2x6 4x6 Timbers – larger than 2 inches in thickness e.g. 4x6 Carpentry First Canadian Edition © 2009 Nelson Education Ltd.
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Actual vs. Nominal Actual dimensions of lumber are smaller than the name implies. For example: A nominal 2x6 6″ 2″ 2x6 Carpentry First Canadian Edition © 2009 Nelson Education Ltd.
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Actual vs. Nominal Is actually 1 ½″ × 5 ½″ 1 ½″ 2x6 5 ½″ Carpentry
Actual dimensions of lumber are smaller than the name implies. For example: A nominal 2x6 5 ½″ 1 ½″ Is actually 1 ½″ × 5 ½″ 2x6 Carpentry First Canadian Edition © 2009 Nelson Education Ltd.
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Actual vs. Nominal Nominal Actual 1x4 ¾″ x 3 ½″ 2x4 1 ½″ x 3 ½″ 1x6
Carpentry First Canadian Edition © 2009 Nelson Education Ltd.
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Actual vs. Nominal Nominal (inches) Actual 1x4 19 x 38 2x4 38 x 89 1x6
37 Actual vs. Nominal Nominal (inches) Actual (millimetres) 1x4 19 x 38 2x4 38 x 89 1x6 19 x 140 2x6 38 x 140 1x8 19 x 184 2x8 38x 184 1x10 19x 235 2x10 38 x 235 1x12 19 x 286 2x12 38 x 286 Carpentry First Canadian Edition © 2009 Nelson Education Ltd.
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Lumber Volume Lumber may be purchased by the piece.
e.g., 36 – 2x8–16′ Large quantities of lumber are often purchased by the board foot (bdft). e.g., 750 bdft of 2x4’s This is typically done at the wholesale level. Also allows for varying board lengths. Carpentry First Canadian Edition © 2009 Nelson Education Ltd.
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Board Foot Measure (cont.)
Formula for figuring board feet is: Bdft = # pieces × Thickness″ × Width″ × Length′ ÷ 12 Note: Thickness (inches), Width (inches), & Length (feet) Example – How many board feet are in 180 pieces of 2x816′ long? Answer: 3840 bdft. 180 × 2 × 8 × 16 ÷ 12 = 3840 bdft Carpentry First Canadian Edition © 2009 Nelson Education Ltd.
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Carpentry First Canadian Edition © 2009 Nelson Education Ltd.
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Conclusion Wood can be air dried or kiln dried
There are different grades of wood Care must be taken to store wood in a dry place with good air circulation Carpentry First Canadian Edition © 2009 Nelson Education Ltd.
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