3311 - Wood Module

1
Wood
2
Terminology and Classification
The terms wood, lumber, and timber are often used
interchangeably, but each term has a distinct
meaning. Wood Hard fibrous substance lying
beneath the bark of trees. Lumber Wood that has
been sawn into construction members. Timber
Lumber that is five inches or larger in its
least dimension.
3
Terminology and Classification
Wood is classified as softwood or hardwood
depending on the type of tree it originates
from. Softwoods, such as pine, fir, and spruce,
come from needle-leaved conifers, which are
evergreen Hardwoods, such as maple, oak, and
sycamore, come from broad-leaved deciduous trees,
which shed their leaves annually. The important
difference between softwoods and hardwoods is
botanical, which refers to the cellular structure
of the two groups. Most hardwoods are in fact
harder than softwoods however balsa wood, one of
the softest woods known is actually a hardwood.
4
Characteristics of Wood Wood consists of
approximately 70 cellulose and 18 to 28
lignin, which is the adhesive imparting strength
to the wood. The remainder is made up of
minerals and extractives, which give wood its
color, odor, and resistance to decay.
5
Cutting and Sawing Lumber
Lumber can be cut from a log in two different
ways tangent to the annual rings, called
plain-sawed in hardwoods and flat-grained or
slain-grained in softwoods. Lumber cut radially
to the annual rings is called quarter-sawed in
hardwoods, and edge-grained or vertical-grained
in softwoods.
Lumber is classified as quarter-sawed if the
grain is 45 degrees to 90 degrees to the wide
face and plain-sawed if the grain is 0 degrees to
45 degrees to the wide face.
6
PLAIN SAWNED LUMBER AND TIMBER
QUARTER SAWNED LUMBER AND TIMBER
7
Cutting and Sawing Lumber

• Characteristics of plain-sawed lumber include
• Distinct grain pattern,
• May twist, cup, or wear unevenly,
• Tends to have a raised grain,
• Shrinks and swells more in width, less in
  thickness,
• Less waste in cutting, and therefore less
  expensive.

8
Cutting and Sawing Lumber

• Characteristics of quarter-sawed lumber include
• Relatively even grain pattern,
• Wears evenly with less warpage,
• Shrinks and swells more in thickness, less in
  width,
• More waste in cutting and therefore more costly.

9
Shrinkage, distortion, and warpage of lumber
depends partially on the way lumber is cut from a
tree. Wood shrinks most in the direction of the
annual growth rings (tangentially) less across
these rings (radially) and very little parallel
to the grain (longitudinally).
10
Seasoning of Wood shrinkage stiffness
strength
As moisture content in the cells of wood changes,
particularly as it dries out, wood members can
change shape if the change moisture content is
not done in controlled conditions. As wood dries
out the amount of shrinkage differs in various
directions. Shrinkage is limited to parallel to
the grain of the wood. It is greatest when
measured in a tangent to the growth rings. The
amount of shrinkage along the radius of the wood
is less than that tangentially. Depending on
where in the log the member is cut from,
uncontrolled drying can cause wood members to
exhibit unusual shapes as shown here in this
exaggerated illustration.
11
Seasoning of Wood shrinkage stiffness
strength appearance
Making wood suitable for construction involved
more than simply cutting down a tree and sawing
the wood to size. Wood in a tree is green, that
is, contains a large amount of water. If green
lumber is used in construction, it will shrink as
it dries out.
Making wood suitable for construction involved
more than simply cutting down a tree and sawing
the wood to size. Wood in a tree is green, that
is, contains a large amount of water. If green
lumber is used in construction, it will shrink as
it dries out. To minimize shrinkage, lumber
should be seasoned dried before use to between10
to 20 moisture content. This can be accomplished
by air drying, which takes several weeks or
kiln drying.which takes only a few days. Over 90
of lumber is kiln dried Framing lumber is
considered seasoned if its moisture content is
19 or less. An 18 2x10 loses approx 5 gallons
of water
Hardwood Inc.Tour Tuesday, Sept. 6, 2011
12
Drying Lumber Video 139 minutes
13
Wood Defects
Variety of defects affect the strength appearance
use and grading of lumber. Defects may be
natural. damaged by insects decayed by fungus
and of course, destroyed by fire. or caused by
manufacturing
14
Wood Defects
NATURAL DEFECTS
Knot branch embedded in a tree and cut through
manufacturing. Shake pitted area sometimes found
in cedar and cypress. Pitched Pocket opening
between growth rings and containing resin.
15
Wood Defects
MANUFACTURED DEFECTS
Check lengthwise grain separation caused by
seasoning. Split lengthwise separation of wood
extending from one face to another. Wane lack of
wood on the edge or corner. Warp shrinkage
distortion of a plane surface, includes---bow,
crook, cup and twist.
16
Wood can be damaged by insects and decayed by
fungus
Pressure Treating Lumber Video 101 minutes
17
Standardized terms and dimensions
18
Standardize Dimensions Nominal Verse Actual size
19
Plywood Veneer Cutting
forms random pattern
forms repeating pattern
forms parallel pattern
20
Sample Plain Sliced Patterns
21
Sample Quarter Cut Patterns
22
Miscellaneous Panels
running match
book matching
balance match
slip matching
random matching
center match
23

Book Match

• Every other veneer turned over
• Veneer joints match, creating symmetrical pattern
• Most common
• Used with plain slicing most

24
Slip Match

• Leaves slipped off in sequence without turning
• Repeating grain - joints dont match
• Often used with quartered or rift veneers

25
Random Match

• Veneer book broken
• Leaf sequence destroyed on purpose
• Appearance of boards
• Casual or Rustic
• More difficult than Book or Slip

26
T Tension C Compression
Wood is generally stronger in compression than
tension. Unlike other materials, the strength of
wood is not the same in every direction for
tension and compression. Wood is stronger when
the load is applied parallel to the grain than
perpendicular to the grain. In fact, the strength
of wood in tension perpendicular to the grain is
so low that this type of loading can easily cause
the wood to split.
For shear, wood is very strong perpendicular to
the grain and relatively weak parallel to the
grain. Therefore, horizontal shear stress
(parallel to the grain) is often a design
consideration, while vertical shear stress
(perpendicular to the grain) is not.
27
Wood Species
What is Southern Pine? Video 100 minute
28
Wood Species Guide

• http//www.hardwoodweb.com/lumber/rfq/quotes.cfm?d
  oguide

29
Example of what we will see at tourPurpleheart
Lumber
Sources Includes species in tropical regions of
Central America and South America. Appearance
Generally straight grained, sometimes
interlocked, with a fine even texture. Creamy
white sapwood and vibrant purple heartwood that
turns to dark-purplish brown with exposure to
light. Physical Properties Very heavy, hard,
strong, and stiff with good decay resistance and
stability in service. Steam-bends moderately
well. www.exotic-wood.com/purpleheart.htm
30
(No Transcript)
31
Structural Strength of Wood

• Species ( Fir, Hemlock, Pine, etc)
• Grade
• Direction of Grain ( parallel or perpendicular)
• Size and Shape
• Moisture Content

32
(No Transcript)
33
(No Transcript)
34

• Definition of Moisture Content
• Weight of water compared to the weight of dry
  wood
• Formula for Moisture Content
• Weight of water as of wt. of dry wood

35

• What is considered an acceptable moisture content
  of framing lumber?

36

• What is considered an acceptable moisture content
  of framing lumber?
• 19
• Weight of the water in the wood is 19 of the
  weight of the dry wood.
• If the wood was 100 pounds dry, then it has 19
  pounds of water in it.

37
Wood
38
(No Transcript)
39
Engineered Wood Products

• Particle Board
• MDF
• OSB
• LVL
• LSL
• Masonite
• Plywood
• Glulam
• Plastic Lumber
• Wood I-Beams
• Wood Trusses

• Structural Wood Panels
• plywood
• composite panel
• non-veneered panel

40
Particle Boardmanufactured from wood particles,
such as wood chips, sawmill shavings, or even saw
dust. Made with larger pieces of wood than used
to make MDF
41
Oriented Strand Board (OSB)sometimes called
waferboard
42
Oriented Strand Board (OSB)
43
O S B Video 108 minutes
44
Medium Density Fiberboard (MDF)Combination of
softwood fibers, wax resin. Stronger than
particle board
45
Laminate Strand Lumber (LSL)Made up of strands
of lumber instead of veneers
46
Laminated Veneer Lumber (LVL) LVL is made by
gluing sheets of veneer together. Unlike plywood,
here all veneer layers are going in the same
direction. Wide panels are manufactured to the
thickness of the desired lumber. The panels are
ripped into lumber of nominal width.
47
Masonite Type of hardboard invented by
William H. Mason.1 It is formed using the Mason
method, using wooden chips and blasting them into
long fibers with steam and then forming them into
boards. The boards are then pressed and heated to
form the finished boards. No glue or other
material is added.
48
Plywood made from thin sheets of wood veneer,
called plies or veneers, layered in opposite
directions
49
What is hardwood plywood?

• Three or more layers of wood or wood products
  laminated into a single sheet
• FACES Outside decorative veneers
• CORE MDF, PB, VC, Combos

50
Construction balance

• Three is minimum
• Always Odd3, 5, 7, 9
• Panel Balance a Must!

51
Plywood Video 2.21 minutes
52

• Plywood is classified as interior or exterior
  depending on the type of adhesive used
  moisture-resistant for interior use, and
  water-proof for exterior use. Plywood used in
  construction is primarily softwood. Plywood used
  for interior millwork or cabinetry is usually
  hardwood. .

53
Plywood Plywood is classified as interior or
exterior depending on the type of adhesive used
moisture-resistant for interior use, and
water-proof for exterior use. Plywood used in
construction is primarily softwood. Plywood
used for interior millwork or cabinetry is
usually hardwood. Plywood is graded according
to quality of the veneer A BestD poorest.
54

• Span Rating
• First number - maximum recommended roof span in
  inches if used as roof sheathing
• Second number -maximum recommended span use
  as subflooring.

For example, a panel identified as 32/16 can be
used as roof sheathing over rafters spaced 32
inches on center or as subflooring over joists
spaced 16 inches on center.
55
Glued Laminated Lumber (Glulam) These beams are
made by gluing many boards together to form a
structural member bigger than the trees from
which the board were sawn. Since the load is
carried by the material in the top and bottom
faces and the middle only has to resist shear,
high quality lumber is used in the top and bottom
while medium grade lumber is used in the center.
(gluelam or glulam) Joints between boards are
typically scarf or finger joints.
56
Glue Laminated Construction
Curves that remain in one plane are much easier
to construct than compound curves (a dome). A
dome is likely to be segmented curves.
57
(No Transcript)
58
Glulam Video 204 minutes
59
RPL Recycled Plastic LumberLumber-like products
with a plastic content of 50 or more. Higher
expansion contraction with temperature changes.
Less structural strength
60
I-Beams I-JoistsVeneer lumber is used for
the flanges and plywood or OSB is used for the
web to resist shear.
61
I - Joist Video 248 minutes
62
Wood Trusses
Fink Truss
63
Wood Siding
64
? end