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wood questions - chapter 3

Terms

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plainsawed
Most lumber intended for use in the framing of buildings is plainsawed, a method of dividing the log that produces the maximum yield and therefore the greatest economy.
quartersawn
Used in applications where different appearances of the wood or different erosion rates would cause a problem, such as finish flooring, interior trim, and furniture. Hardwoods are often quartersawn to produce pieces of lumber that have the annual rings running nearly perpendicular to the face of the piece. Boards with this vertical grain tend to remain flat despite changes in moisture content.
Almost every piece of lumber contains one or more discontinuities in its structure caused by:
growth characteristics of the tree from which it came or
manufacturing characteristics that were created at the mill.
Among the most common growth characteristics are
knots - which are places where branches joined the trunk of the tree;
knotholes - which are holes left by loose knots dropping out of the wood;
decay and insect damage

Knots & knotholes reduce the structural strength of a piece of lumber and often considered detrimental to its appearance. Decay & insect damage may or may not affect the lumber.
Manufacturing characteristics arise largely from
changes that take place during the seasoning process because of the differences in rates of shrinkage with varying orientations to the grain.

Splits & checks are usually caused by shrinkage stresses. Crooking, bowing, twisting, and cupping all occur because of nonuniform shrinkage.
Wane
Wane is an irregular rounding of edges or faces that is caused by sawing pieces too close to the perimeter of the log. Experienced carpenters judge the extent of these defects and distortions in each piece of lumber and decide accordingly where and how to use the piece in the building.
The effects of cupping in flooring and interior baseboards and trim are usually minimized by
using quartersawn stock and by shaping the pieces so as to reduce the likelihood of distortion.
Each piece of lumber is graded either for:
appearance or for structural strength and stiffness, depending on its intended use, before it leaves the mill.

Lumber is sold by species and grade; the higher the grade, the higher the price.
In determining the 'real size of lumber'

- 1" subtract ____
- 2",4", 6" subtract ____
- 8", 12" subtract _
1" - subtract 1/4"

2",4", 6" subtract 1/2"

8", 12" subtract 3/4"
Give the actual cross-sectional dimensions of the following pieces of kiln-dried lumber:
1 x 4
2 x 4
2 x 6
2 x 8
4 x 4
4 x 12
given 1 x 4; actual 3/4" x 3-1/2"
given 2 x 4; actual 1-1/2" x 3-1/2"
given 2 x 6; actual 1-1/2" x 5-1/2"
given 2 x 8; actual 1-1/2" x 7-1/4"
given 4 x 4; actual 3-1/2" x 3-1/2"
given 4 x 12; actual 3-1/2" x 11-1/4"
Why is wood laminated?
Originally, to overcome shortcomings of solid wood, but with new consciousness of sustainability, focus is on maximized utilization of wood fiber from each tree. Year by year, a larger and larger percentage of wood fiber used in buildings is in the form of manufactured wood products.
There are 3 major reasons to laminate:
1. size - any desired size of structural member can be laminated, up to the capacities of hoisting & transportation needed to deliver it.
2. shapes can be obtained that cannot be obtained in nature - curves, angles, cross sections u-shaped timber for a ship.
3. Quality can be closely controlled. Seasoning is carried out prior to lamination, eliminating checks and distortions that characterize solid timbers.
Why would you specify preservative-treated wood?
Deck, outdoor furniture or wood foundation. Roof sheathing on attached structures so that the wood is pressure impregnated with a chemical that makes it more fire-resistant.
Fire resistance and decay and insect resistance are the two main reasons to treat wood.
What common species of wood have decay- and insect-resistant heartwood?
The heartwood of some species of wood is naturally resistant to decay and insects and can be used instead of preservative-treated wood. The most commonly used decay-resistant species are:
Redwood, Bald cypress, and Red and White cedars. The sapwood of these species is no more resistant to attack than that of any other tree, so "All-Heart" grade should be specified.
Why are nails the fastener of choice in wood construction?
Nails are the favored means of fastening wood because they require no predrilling of holes under most conditions and they are extremely fast to install.
1. Woods used for framing, sheathing, paneling are________ such as: ____________
2. Woods used for moldings, paneling, furniture are ______ such as:
3. What is generally used for houses?
____________
1. softwoods used for framing, sheathing paneling are: western hemlock, Idaho white pine, white spruce
2. Woods for moldings, paneling furniture are hardwoods such as ash, cherry, mahogany
3. Woods generally used for houses are pine, white wood.
An advantage of using plywood over paneling or particle board is that
plywood doesn't outgass like paneling or particle board does.
A wood resistant to termites
redwood
A wood used for moldings, window and door frames
Ponderosa pine (softwood - white)
Decay-Resistant Woods, Used for Shingles, Siding, Outdoor Structures
California redwood, Southern cypress, Western red cedar, White cedar
What's OSB?
Oriented Strand Board
Evolving from waferboard in the late 1970s, OSB is unique in that long wood strands are oriented, not randomly placed. Since its debut in 1978, OSB has been rapidly accepted. In fact, in many areas of North America, OSB has virtually replaced other panels in new residential construction. Today, all model building codes in the U.S. and Canada recognize OSB panels for the same uses as plywood on a thickness-by-thickness basis.
Framing lumber is considered to be seasoned when
its moisture content is 19% or less. For framing applications that require closer control of wood shrinkage, lumber seasoned to a 15% moisture content, labeled "MC 15" is available. It is of little use to season framing lumber below 13% because wood is hygroscopic and will take on or give off moisture to stay in equilibrium with the moisture in the air.
Pieces of lumber less than 2" in nominal thickness are called _______.
Pieces ranging from 2 to 4 inches in nominal thickness are referred to collectively as ______ _______.
Pieces nominally 5 inches and more in thickness are termed ______
< 2" = boards

2 - 4 " = dimension lumber

>= 5" = timbers
Lumber in the U.S. is priced by the ________ _______, which is based on __________.
priced by the board foot which is based on nominal dimensions, not actual dimensions.

A board foot of lumber is defined as a solid volume 12 sq. inches in nominal cross-sectional area and 1 foot long.
Other parts of world sold by cubic meter.
Veneers for structural plywood are ________ sliced, which is the most economical, giving a grain which is __________ and _________.
Face veneers for hardwood plywood, flitches are _________ or __________.
The finest figures on the grain are pro
rotary sliced, which is the most economical, giving a grain which is broad and uneven.

Face veneers for hardwood plywood are plain sliced or quarter sliced. The grain produced by quarter slicing results in a very close grain pattern with prominent rays.
Standard plywood panels are
___ by ___ feet in surface area and range in thickness from ____ to _____
4 x 8 feet in surface area and range in thickness from 1/4 to 1 inch.
The 3 methods of fastening with nails are
1. face nailing is the strongest of the 3 methods.

2. End nailing is relatively weak and is useful primarily for holding framing members in alignment until gravity forces and applied sheathing make a stronger connection.
3. Toe nailing is used in situations where access for end nailing is not available. Toe nails are surprisingly strong - load tests show them to carry about 5/6ths as much load as face nails of the same size.
joist hangers
joist hangers are used to make strong connections in floor framing wherever wood joists bear on one another at right angles.
heavier steel beam hangers are used primarily in
laminated wood construction.
Post bases serve two functions
1. prevents water from entering the end of the post
2. anchors the post to the foundation.
Example sheet metal connectors shown in the diagram in the book are less commonly used than the hangers but are invaluable in solving special framing problems and in reinforcing frames against wind uplift and earthquake forces. 3 types:
1. rafter anchor
2. framing anchors
3. angle
Three types of prefabricated wood panels.
The framed panel is identical to a segment of a conventionally framed wall, floor, or roof.

The facings on the stressed-skin panel are bonded by adhesive to thin wood spacers to form a structural unit in which the facings carry the major stresses.

A sandwich panel functions structurally in the same way as a stressed-skin panel, but its facings are bonded to a core of insulating foam instead of wood spacers.

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