| Term |
Description |
| Seasoning
stresses |
Stresses
in timber caused by variation in shrinkage as it dries. |
| Select |
A
high grade of lumber that allows few defects. |
| Selects |
In
softwood, lumber which has been graded strictly for its
appearance. In hardwood, lumber which is one grade below
first and second. |
| Shade
tolerance |
The
capacity of a tree or plant species to develop and grow
in the shade of and in competition with other trees or
plants. |
| Shake |
lumber
defect referring to a separation of wood fiber through
the annual growth rings. |
| Shake |
Separation
or breakage of the wood fibres caused by stresses in
the standing tree or by felling and handling of the log.
It is not caused by shrinkage during drying. |
| Shake |
A
separation of the wood along an annual ring (ring shake)or
cracks radiating from the heart (heart shake) caused
by frost, wind, or felling of the tree. |
| Shear |
A
condition of stress or strain where parallel planes slide
relative to each other. |
| Shear
connector |
Usually
metal connectors fitted inside a timber joint to transfer
shear across a wide area of grain. |
| Shear
Stress |
Result
from forces which tend to cause one portion of a body
to move with respect to another in a direction parallel
to their plane of contact. |
| Sheet
metal connector |
A
shaped connector made of sheet metal and perforated so
that nails can be driven through. |
| Shelterbelt |
A
wind barrier of living trees and/or shrubs maintained
to protect farm fields or homesteads. |
| Shelterwood
cutting |
Any
harvest cutting of a more or less regular and mature
crop, designed to establish a new crop under protection
of the old. |
| Shipment
time |
The
time indicated for a shipment of lumber to leave a sawmill
or reload center. |
| Shipper |
The
party paying the freight bill. |
| Short
(position) |
A
speculative position in which one sells lumber before
it is bought. |
| Shrinkage |
The
reduction in dimension or volume which takes place in
timber when the moisture content is reduced below fibre
saturation point, expressed as a percentage of the original
dimensions or volume. Linear shrinkage occurs in three
directions radial, tangential and longitudinal. |
| Shrinkage |
The
percentage change in the dimension of wood with respect
to the swollen size as a basis. |
| Sidecuts |
Boards
usually 1x3, 1x4 or 1x6 produced in a dimension mill
from the thin slabs taken from the outside of logs; slabs
not thick enough to make dimension lumber. |
| Sill |
1)
A sill plate. 2) The structural member forming the bottom
of a rough opening for a door or window. Also, the bottom
member of a door or window frame. |
| Silviculture |
The
art and science of growing and tending a forest. It includes
assessing sites before they are harvested to determine
what is growing there now, evaluating soil conditions
to determine moisture and nutrient levels as well as
assessing the types of plants that are growing on the
site. |
| Skidder |
A
wheeled or tracked vehicle used for sliding/dragging
logs from the stump to the landing. |
| Slab |
A
broad flat piece of wood cut directly from the log, often
with bark on both edges. |
| Slab |
The
exterior portion of a log removed in sawing timber. |
| Slash |
Tree
tops, branches, bark, and other debris left after a forest
operation. |
| Sliced
veneer |
Veneer
that is sliced off a log or flitch with a knife. |
| Sliding
Dovetail Joints |
A
sliding dovetail joint is similar to a tongue and groove
joint except the tongue and grove are matching dovetails. |
| Softwood |
Wood
from trees commonly referred to as conifers or evergreens. |
| Softwood |
A
general term for timber of trees classified botanically
as Gymnosperm. Commercial timbers of this group are nearly
all conifers. The term has no reference to the relative
hardness of the wood. |
| Softwood |
Evergreen
trees, conifers, cone-bearing trees or wood cut from
these trees. Softwood lumber has long been the mainstay
of the residential construction industry where it is
used in relatively large-sized pieces. Though some of
this wood, such as that used for siding, must be of good
appearance, most requires only adequate strength. Because
of these factors, and because construction requires material
of uniform size which can be stockpiled economically
(meaning a relatively small number of standard sizes),
softwood lumber is manufactured to standard sizes and
is measured accordingly. |
| Softwoods |
Generally
lumber from a conifer such as pine or cedar. The name
softwood does not refer to the density of the wood. There
are some hardwoods, such as Balsa, which are softer than
some softwoods, like Southern Yellow Pine. |
| Sound |
A
term referring to a board which has no or very few defects
which will effect its strength. |
| Sound
knot |
A
knot that is solid across its face, at least as hard
as the surrounding wood, and shows no indication of decay. |
| Spar |
A
pole, tower or tree used in cable logging to raise the
mainline off the ground. |
| Specific
Gravity |
The
decimal ratio of the ovendry weight of a piece of wood
to the weight of a volume of water equal to the volume
of the piece at a given moisture content (green, air-dry,
or ovendry). |
| Specific
Gravity |
The
ratio of the weight of wood to an equal volume of water.
The higher the specific gravity, the heavier the wood. |
| Spermatophyte |
Plants
that reproduce by seeds. This includes almost all plant
species. |
| Spike
top |
A
tree with a dead top, usually a mark of declining vigor. |
| Spindle |
The
threaded arbor on a shaper that holds the cutters. |
| Splice |
To
join the ends of timber elements together. |
| Spline |
A
thin piece of wood that fits in the mating grooves cut
into two pieces of wood. |
| Split |
A
defect that occurs when tensile stresses cause the wood
fibres to separate and form cracks. Splits are cracks
that extend through a piece. |
| Spring |
A
longitudinal curvature of the edge of a piece of timber,
not affecting the face. |
| Springing |
Support
point or origin. |
| Springwood |
The
less dense, larger wood cells of an annual growth ring.
Also called earlywood to refer to the fact that it is
the wood formed early in the growing season. See also
summerwood. |
| Squeeze-out |
A
bead or drops of glue that are forced out of a joint
when pressure is applied. |
| Stain |
1)
A discoloration in wood caused by a fungus or chemicals.
2) A die or pigment used to color wood. |
| Stand |
A
community of trees sufficiently uniform in species, age,
arrangement or condition to be distinguishable as a group
from the forest or other growth on the area. |
| Starved
Joint |
A
poorly bonded joint caused by lack of glue. |
| Steam
bending |
The
curvature to which a 1 inch
(25mm) thick sample may be
steam bent with an expectation
of a 5% failure rate. |
| Steaming
treatment |
A
treatment sometimes carried out before commencing a drying
schedule. The timber is subjected to live steam. See
also reconditioning. |
| Stem
Wood |
See
Bole Wood. |
| Sticker Ñ |
A
thin wood strip that is inserted between stacks of green
wood to allow air to flow through the stack to ensure
proper drying.. |
| Stickers |
Strips
or boards used to separate the layers of lumber in a
pile and thus improve air circulation. |
| Stickers |
When
kiln or air-dryin wood, stickers are pieces of wood placed
perpendicularly between layers of boards to allow for
airflow through the stack. Stickers are usually placed
12 to 18 inches apart and directly over any support beams
under the stack. Placing stickers as close as possible
to the end of the boards helps to llimit end checking
and reduce warp. |
| Stiffener |
All
elements used to support or stiffen the slender webs
of box and I-shaped beams and to enhance compressive
capability of webs at support points or points of high
transverse loads. |
| Stile |
The
vertical part of a raised panel door. |
| Stitch
bolt |
A
long bolt through laminated timber that holds the laminations
together. |
| Straight
grained |
Timber
in which the fibres run parallel to the axis of a piece. |
| Strength |
The
ability of a member to sustain stress without failure. |
| Strength
group |
Species
of timber are classified into groups according to mechanical
properties of the wood of that species and AS 2878, Timbers
- Classification into Strength Group. There are seven
strength groups for unseasoned timber (S1 the strongest
to S7 the weakest) and eight for seasoned timber (SD
1 the strongest to SD 8 the weakest). |
| Stress |
Applied
force per unit of volume or area. It is expressed as
primary stresses, i.e., compression (with forces acting
toward each other), tensile (with forces acting away
from each other), or shear (with forces sliding on each
other). A combination of the three results in bending
stresses. |
| Stringer |
1.
A beam that joins the top of columns and supports the
cross members in floors and ceilings. 2. An inclined
member that supports the treads of a stair. 3. A deck
element in timber bridges that supports transverse deck
planks and runs parallel to the beam span. |
| Structural
I-Beams |
Structural
I-Beams were developed to take advantage of the fact
that compression and tension stresses are greatest at
the top and bottom edges of a beam as it is subjected
to a load. By concentrating the amount of wood at the
the top and bottom edges and by paying close attention
to the quality of wood used at these locations, beams
are made that have high strength but which use far less
wood than solid lumber. Such products are widely used
today and were used in 19% of the homes built in the
United States during 1996. Structural I-beams are used
for the most part as floor joists, replacing 2 ´ 12,
2 ´ 10, and 2 ´ 8 solid-sawn lumber that has traditionally
been used for joists. |
| Structural
timber |
Timber
to be used in construction where its strength is the
controlling element in its selection and use. |
| Strut |
A
structural timber resisting compressive forces along
the grain. |
| Stud |
One
of a series of vertical framing timbers used as a supporting
element in a wall or partition. |
| Stumpage |
The
value of timber as it stands uncut in the woods. The
price charged for the right to harvest timber from publically
or privately-owned forest land. The University of Massachusetts
publishes a local stumpage fee report quarterly based
on responses to a survey of local landowners and loggers. |
| Summerwood |
The
denser, later-formed wood of an annual growth ring. Also
known as "latewood" relating to the time in the growing
season that these cells are produced. |
| Sunscald |
Death
of cambial tissue on one side of a tree, caused by exposure
to direct sunlight. |
| Surfaced |
Lumber
that has gone through a planer so that its sides are
smooth and uniform in size. |
| Surfaced
Lumber Ñ |
A
piece of wood that has been planed smooth on one or more
surfaces. |
| Surfacing |
The
way a piece of lumber has been prepared at the lumber
mill. |
| Sustainable
Forestry Initiative (SFI) |
The
program and polices formed by the American Forest and
Paper Association (AFandPA). SFI was developed in response
to criticism from environmentalists aimed at logging
practices that did not promote forest sustainability.
SFI is the industrial counterpart to programs promoted
by Smartwood (non-profit)and Scientific Certification
Systems (for profit) which promote and certify landowners
engaged in proactive and sustainable forest management.
AFandPA requires all its members to comply with SFI principles
among which is the requirement that forest management
be "certified" by an independent third party. SFI certification
can be easily confused with "green certification" promoted
by the Forest Stewardship Council (FSC). |
| Sustained
harvest |
A
level of harvest that does not exceed annual growth,
so that at least as much is available for harvest in
50 years as today. |
| Sway
bracing |
Bracing
members required to resists the transverse movement of
a structural element. |
| Sweep |
A
gradual (but pronounced) bend in a log, pole, or piling;
considered a defect. Sweep in a log is analogous to "bow"
in a piece of lumber. |
| Swell-butted |
Describes
a tree greatly enlarged at the base. |
| Swirl
figure |
A
figure caused by irregular grain in the region of the
knot. |
| Tack
TimeÊ |
The
amount of time it takes for an adhesive to set-up before
it can form a bond. |
| Tally |
The
thickness, width, and length piece count of lumber shipped
on a particular order. |
| Tangential |
Coincident
with a tangent at the circumference of a tree or log,
or parallel to such a tangent. In practice, it often
means roughly coincident with a growth ring. |
| Taper |
Reducing
gradually in width or diameter. |
| Taper |
A
piece of wood that has been cut so that it is wider on
one edge than the other. |
| Tare
Weight |
Tare
weight is the weight of tractor-trailer with no load.
A tractor trailer typically weigh 30,000 to 35,000 pounds
leaving a legal load weight of 45,000 to 50,000 (22 to
25 ton). The heavier overweight loads not only pay the
trucker more, but are also more wear and tear on trucking
equipment. |
| Tearout |
The
tendency for a blade to splinter the last part of a piece
of wood during crosscutting. |
| Tempered
Hardboard Ñ |
Dense
fiberboard that has been specially treated to increase
its durability, strength, density, and moisture resistance. |
| Template |
A
pattern. Often a template is made of hardboard and used
with a pilot bit to route a shape in a board. |
| Template
guide |
A
jig mounted to the bottom of a router that is used to
keep the router on the profile of a template when routing
with a non-pilot beating bit. |
| Tenon |
A
protrusion from a board that fits into a matching mortise
to form a joint. |
| Tensile
Stress |
The
total tension force (force acting on a body which tends
to increase its dimension, or volume) divided by the
cross-sectional area of the body upon which the load
is applied. |
| Tension |
A
state or condition of being pulled or stretched by a
force. |
| Tension
Wood |
Abnormal
wood formed typically on the upper sides of branches
and leaning or crooked stems of hardwoods. It is characterized
by the presence of gelatinous fibers and excessive longitudinal
shrinkage. Tension wood fibers are strongly held together
which often causes sawed surfaces to exhibit projecting
fibers, and planed surfaces to produce torn or raised
grain. |
| Tension
Wood |
Reaction
wood that forms on the upper side of a leaning hardwood
tree. |
| Texture |
Characteristic
determined by the size and quality of the wood elements.
Descriptive terms include fine, medium, uniform, even,
uneven, coarse. |
| Texture |
The
relative differences in appearance of the growth increment,
resulting from variations in size and uniformity in dimensions
between earlywood and latewood cells. Coarse Texture-Texture
resulting from wide bands of large open elements, or
broad rays. Can also result from uniformly distributed
cells with large lumina; Fine Texture-Fine textured wood
has narrow vessels and thin rays. Fine textured wood
is further classified as even or uneven. Even texture
is the result of uniformity in cell dimensions and lumina,
accompanied by inconspicuous rays. |
| Thinning |
The
process of removing excess and poorer quality trees from
a stand to allow the remaining trees adequate sunlight,
nutrients and moisture and to grow at an even rate which
improves stand value. Trees that remain when surrounding
trees are removed in thinnings or partial cuttings respond
to this more open environment by stimulated crown development
and the formation of wider growth rings along the bole.
Effects upon growth are often dramatic. The effect on
density of wood formed thereafter is largely unpredictable.
However, the timing of thinnings has much to do with
the effect upon wood quality and thus should be considered
when developing a management plan. |
| Thousand
Board Feet (MBF) |
One
board foot is wood that measures 1" x 12" x 12". Logs
and lumber are measured by MBF or thousand board feet.
MBF is determined by one of three major scaling rules:
Scribner, Doyle, or International Rule. The board feet
scaled for logs is an estimate only. The actual board
feet yield depends on how the sawmill cuts the log. It
is possible for a log to produce more board feet than
was estimated producing an overrun. |
| Thousand
board feetÑ |
The
unit of measure most frequently used in the lumber industry. |
| Through
Dovetail Joint |
A
method of joining wood where the interlocking pins and
tails of the dovetail joint go through the side of its
mating piece. |
| Tie |
A
structural member resisting
tension forces along the
grain. |
