Woodipedia Index

Wood Terms that Start with "S"

Lumber Glossary Term Definition

Surfaced one face

S2S Surfaced two faces

Surfaced two sides, one edge


Surfaced two faces and straight line ripped one edge

S4S Surfaced two faces and straight line ripped two edges

Society of Automotive Engineers

Safety Guy A line rigged under the bull block to take it to the ground if the holding straps break.
Safety Swede

A lever used to tighten binders on loaded logging trucks.

Sag Slack in a cable, particularly in a skyline.
Salvage Logging

A cleanup operation, generally with a small crew and light equipment, which collects merchantable material too small to be handled economically with big equipment. Salvaging timber damaged by wind, insect, fire, ice, or other natural causes.

Sand Bolster Part of a landing gear that rests on the ground, across and between the two upright portions.
Santos Mahogany
  • Range of colors between light orange to a dark reddish-purple brown
  • Interlocked grain
  • Moderately difficult to machine
  • High density
  • Used for fine furniture, interior millwork, hardwood flooring, stairs and molding.
Sap The water in a tree which is rich in minerals and nutrients.

Young tree less than 4 inches in D.B.H. The minimum diameter or saplings is usually, although not always, placed at 2 inches.


The new wood in a tree that lies between the bark and the heartwood. Sapwood is usually lighter in color and becomes heartwood as the tree ages.


A frame structure, normally glazed, that is hung or fixed in a frame set in an opening.


A trestle usually used in pairs to hold wood for cutting.


A basic, cutting process that uses a blade set with a series of teeth on its edge to cut a narrow opening in a work piece. Sawing may be used to produce slots or grooves or to separate the work piece into two pieces.

Saw Kerf

Grooves or notches that are made in cutting with a saw.

Sawlog Portion

That part of the bole of saw timber trees between the stump and the saw log top.


Logs meeting minimum regional standards of diameter, length, and defect. Logs must be at least eight feet long, have a minimum diameter inside bark of six inches for softwoods and eight inches for hardwoods, and maximum defect as specified by regional standards.

Saw Timber

Trees suitable for production of saw logs.


A brand of reciprocating saw manufactured by the Milwaukee Electric Tool Company.

Scale ‘lb’ measure the weight or volume of a log or load of logs.

Determination of the gross and net volume of logs using the customary commercial volumetric units for the product involved.


Removing small plants and duff or ashes from around the spot where a tree seedling will be planted. This is usually done by hand rather than by machine.


A temporary platform either supported from below or suspended from above, on which workers sit or stand while performing tasks at heights above the ground.


Shallow loosening of the soil surface.

Scarf Joint

A joint used to splice two timbers end to end.

Schedule Maching Hour Time in which a machine is intended to be operated and has an operator scheduled.
Schoolmarm A tree that initially had a single trunk that later split into two separate trunks part way up the tree.

A two-runner sled, without tongue or shafts, used to haul logs or bolts from the woods.

Screw Gun

A tool used to install sheetrock, also known as drywall. Screw guns look like a normal drill, although they have a “nose” as opposed to a chuck. The nose holds an interchangeable shank bit, commonly known as a tip.


Shaping one member to the surface which it touches; for example, to fit a board snugly to a surface which is not straight.

Scribner Rule The diagram log rule, one of the oldest in existence, that assumes 1-inch boards and ¼-inch kerf, make a liberal allowance for slabs, and disregards taper. This is the official rule of the Canadian Forestry Branch, Department of Resources and Development, and also used in many part of the United States.
Sealed Bid Sale Sale in which interested parties submit written bids at the time and place specified.

Wood that has been dried to a certain moisture content to improve its serviceability. According to the grading standards of the Western Wood Products Association, seasoned softwood lumber is defined as having a moisture content of 19% (oven-dry basis) or less.


The process of removing the moisture from green wood to improve its workability and stability.

  • Air Dried – Dried by exposure to air in a yard or shed, without artificial heat.
  • Kiln Dried – Dried in a kiln with the use of artificial heat
Second Growth

Trees that come up naturally after the first growth of timber has been cut or destroyed by fire. This is also known as young timber.

Secondary Logging Road

A road designed for relatively little use. Typically, a dirt road, with no gravel, used only during dry weather.

Secondary Rafters

Smaller sized timber rafters placed between principle rafters.

Secondary Transport

Movement of wood from the landing or transfer point. This includes movement by truck, rail, or water.

Secondary Wood

This is the material used in furniture that is not seen or on the sides or back of an object. These are the materials that make up the drawer sides, dust panels, backs and other hidden parts.


A land survey subdivision. This is usually one square mile (640 acres).


An area prepared to receive seeds, such as an area cleared of plants and duff, so that natural seed fall can establish a new forest.

Seedling A young tree grown from a seed, from the time of germination until it reaches sapling size. In nursery practices it is a young tree that has not been transplanted.
Seedling and Sapling Stands

Where ten percent of the stand consists of growing-stock trees, and saplings and/or seedlings constitute more then half this stocking.

Seed Block

Used to describe uncut blocks of trees that are left between and around small clear-cut blocks to provide seeds for natural regeneration.

Seed Tree

A horizontal timber to which the tops of rafters are fastened. This is also called a ridge board or a roof tree.


In softwood lumber, the highest appearance grades are Select grades, usually separated as “B and better”, “C”, and “D” select grades. In hardwood factory lumber, Selects is one specific grade, placing in quality below Firsts and Seconds, but higher than Common grades.

Select Grade

High-quality lumber. This grade is recommended for all finishing uses where fine appearance is essential. Widely used for high-quality interior trim and cabinet work with natural, stain, or enamel finishes.

Selection Cutting

Cutting only a portion of the trees in a stand; usually those marked or designated by a forester.

Selection System

Uneven-aged silvicultural system in which single or small groups of trees are periodically selected to be removed from a large area so that the age and size classes of the reproduction are mixed.

Selection Thinning

Removal of dominant trees that have exceeded the diameter limit prescribed; in favor of smaller trees with good growth form and condition. This will promote conversion to a selection forest.

Selective Cut

A type of timber harvesting that removes only certain species above a certain size or value.


In softwood, lumber which has been graded strictly for its appearance. In hardwood, lumber which is one grade below first and second.

Self Loader

Logging truck with a loading device, generally a knuckleboom loader, mounted behind the cab.

Semitransparent Stain

A suspension of pigments in a drying oil designed to color and protects wood surfaces by penetration without forming a surface film and without hiding wood grain.

Separator Wood

Material that has been separated from the whole tree during the chipping process and is unacceptable for pulp and paper manufacture. This is usually used as energy wood.


The teeth are offset on each side of the blade to allow clearance for the thickness of the blade.


Area logged to an one yarder set-up.


The area along a property’s edge where new construction is restricted or forbidden by local zoning laws.


A clevis or U-shaped metal fitting with a pin through the ends.

Shade Structure

A structure built above decks, usually of posts and lattice, to provide a shaded area on the deck.


A lumber defect that is a lengthwise separation of wood; along the growth rings.


Shakes are very similar to checks, but usually wider and longer. They generally work from the heart of the tree outward, at right angles rather than parallel to the growth rings.


A machine with an interchangeable rotary cutter head to cut profile shapes on the edge or face or material


A small wood particle of indefinite dimensions developed incidental to certain woodworking operations involving rotary cutter heads usually turning in the direction of the grain.

Shay Swivel

A fitting used to attach the slack-pulling line to the main line on a skyline system.


Hydraulically operated scissor-like device for crosscutting the stem of a tree. One type of tree shear uses a cutting blade, which closes parallel to the anvil.

Shearing Strength

The capacity of an object or soil to resist shearing stresses.


Lumber, Plywood, oriented strand board, or wafterboard used to close up side walls, floors or roofs prior to the installation of finished materials on the surface. The sheathing grades are also commonly used for crates, pallets, and certain industrial products.


A grooved wheel or pulley.

Sheep's Foot Roller

A steel drum with short metal rods on the outside; sometimes shaped like a sheep’s foot. This is used for compacting soil.


Resin flakes dissolved in alcohol used as a finish for wood.

Shelterwood Logging

A method of harvesting timber so that selected trees remain scattered throughout the tract to provide seeds for regeneration and shelter for seedlings.

Shelterwood System

Even-aged silvicultural system in which a new stand is established under the protection of a partial canopy of trees. The mature stand is generally removed in a series of two or more cuts, the last of which is when the new even-aged stand is well developed.

Shipping Dry

Having moisture content (over-dry basis) of 14 to 20 percent. Results in reduced shipping weight and less susceptibility to decay. This is used in the international lumber trade.

Short Rotation Energy Plantations

Plantings established and managed under short-rotation intensive culture practices.

Short Ton

U.S. weight measure equal to 2,000 pounds.


Pulpwood less than 120 inches in length. Trees or stemwood portions of trees delivered in product lengths of less than 15 feet and normally considered only for pulpwood.


A two-drum, live skyline yarding system used in uphill logging, in which the carriage moves down the skyline by gravity, is lowered to attach logs, and is then raised and pulled to the landing by the main line.


The area of the void created when the waste around a tenon has been cut away.


A tool with a handle and a broad scoop or blade for digging and moving material, such as dirt or snow.


Any unit of operation in the woods associated with timber harvesting.


A decrease in wood dimensions due to loss of water in the wood cell walls. Shrinkage across the grain of wood occurs when the moisture content falls below 30 percent, the fiber saturation point. Below the fiber saturation point, shrinkage is proportional to moisture content, down to a moisture content of zero percent. Shrinkage is expressed as a percentage of the green wood dimensions.

Shuttle Hauling

Use of preloading trailers to reduce truck turn-around time.


A term for an adjoining object being below the object it is next to. This means a little below the surface.


Men and equipment needed to yard and load any one logging unit of an operation.


The finish covering of the outside wall of a fame building, whether made of horizontal weather boards, vertical boards with battens, shingles, or other material.

Sill Timber

Major horizontal timbers which lie on the foundation and form the lowest part of the frame.

Silvicultural System

The process of tending, harvesting, and replacing forest trees, which results in the production of forests with distinct compositions. Systems are classified according to the method of harvest cutting used for stand reproduction.


The science and art of cultivation (such as with growing and tending) forest crops, based on the knowledge of silvics. More explicitly, the theory and practice on controlling the establishment, composition, constitution, and growth of forests.

Single-Action Shear

A mechanized cutting tool that uses one hydraulic cylinder to push the cutting blade through the tree while a fixed anvil provides support for the blade on the trees opposite side.

Single-Span Skyline

Skyline without intermediate support spars.


An operation handling one tree at a time.

Site Class

Classification based on ecological factors and the potential production capacity of an area; a measure of the relative production capacity of a site.

Site Built

A structure constructed at the site where it is to remain.

Site Index

The measure of forest productivity generally expressed as the height in feet of dominant and co-dominant tree species at a specific index age such as 25, 50, or 100 years. Sit indexes are normally grouped by site classes.

Site Preparation

Removal or deadening of unwanted vegetation prior to planting trees; includes prescribed burning, use of herbicides, disking and other mechanical means of removing vegetative cover.

Site Utilization

A term used when indicating the proportion of a useable forest site occupied by healthy, vigorous forest crop trees at any one point in time.


A motor truck with six powered wheels, two in front and four in back.


A load being pulled by the skidder.

Skidding Chain

The length of chain fastened around the end of a log.

Skidding Pan

A plate of heavy steel, round in front, placed under the front end of logs being skidded to prevent them from digging into the ground.

Skidding Tong

The tong used in skidding to grasp a log.

Skid Pole

Logs or poles, commonly used in pairs, on which logs are rolled.

Skid Trail

Skidder path through the woods.


A decorative board placed around the support structure of a deck to hide the structure below and give the deck a finished appearance. Skirts often are attached to the joists.


Cableway stretched tautly between two spar trees and used as a track for a skyline carriage.

Skyline Carriage

A wheeled device that rides back and forth on the skyline for yarding or loading.

Skyline Crane

A yarding system capable of moving logs laterally to a skyline as well as transporting logs either up or down a skyline to a landing.

Skyline Crane Carriage

Skyline carriage that incorporates provisions for pulling slack in the skidding line.

Skyline Road

An area bounded by the length and lateral yarding width of any given skyline setting.

Skyline Slope

The slant or inclination of the skyline chord, generally expressed as a percent.

Slackline System

A live skyline system employing a carriage, main line, and haul-back line. Both main and haul-back lines attach directly to the carriage. The skyline is lowered by a slackening of the line to permit the chokers to be attached to the carriage. Lateral movement is provided by side blocking. For drum standing skyline yarding systems in which either the slack pulling line pulls the main line through the carriage or a carriage that contains a skidding line is used. The haul-back line returns the carriage and holds it in place during lateral yarding.

Slack-Pulling Line

A line used to pull the main line through a logging carriage.


Woody material or debris left on the ground after an area is logged. This is also known as brush.


A machine that bucks Longwood into Shortwood at the landing. This is always known as a bucker.


A wide bladed and long handled chisel pushed by hand to create flat surfaces.

Sliding Miter Saw

A compound miter saw with horizontal sliding arms for the cutter head, allowing much wider cuts.


A loop of wire rope used in loading logs too large to be handled by tongs.


Relative movement in the direction of travel at the mutual contact surface of the traction or transport device and the surface that supports it.

Slip Grab

A pear-shaped link, attached by a swivel to a chain. The chain runs freely through this chain when the large end is down but catches and holds when the small end is down.

Slip Hook

A rounded hook that permits a chain to run freely through it.


A two-runner sled to haul logs or bolts out of the woods. Similar to a scoot except that the sloop is equipped with a tongue.

Small Trees

Live trees 1.0 to 5.0 inches to D.B.H.


A general term describing small-diameter material (such as what might be removed by a pre-commercial thinning) that is typically unsuitable for commercial roundwood products.


A standing dead tree from which the leaves and most of the branches have fallen.


The tendency to gouge the trailing end of material when running it through a joiner.

Snubbing Line

A line used for lowering a load.

Soil Reaction Nomenclature
  • Soil Adhesion – The sticking of soil to foreign materials such as soil implements, tracks, or wheels.
  • Soil Compaction – Increased soil density resulting from the packing effect of machines moving over the soil. Compaction disturbs the soil structure and can cause decreased tree growth, increased water runoff, and soil erosion.
  • Soil Failure – Alteration or destruction of the soil structure by mechanical forces such as in shearing, compression, or tearing.
Soft Rot

Rot occurring in the outer wood layers under very wet conditions.


Lumber often from a conifer, such as pine or cedar. The name softwood does not refer to the density of the wood. There are some hardwoods which are softer then some softwood.

Soft Maple
  • Creamy white and straight grained
  • Medium bending and crushing strengths
  • Low stiffness and resistance to shock loads
  • Works satisfactorily with hand and machine tools
  • Used for domestic flooring, interior joinery, piano actions, sports goods, and paneling
Solid Piling (Bulk Piling)

The close stacking of lumber or other products, without separation of layers with stickers, as in open piling.


The separation of forest products. This usually occurs at the landing.


A term referring to a board which has no or very few defects which will effect its strength.

Sound Wood

Wood that is free from defect.

South American Lacewood
  • Pink to reddish-brown color
  • Highly figured
  • Straight grain with a fine to medium texture
  • Medium strength
  • Low stiffness
  • Works well with hand and machine tools
  • Used for furniture, cabinet making, light construction, paneling, ornamental inlay, and decorative uses.
South American Mahogany
  • Heartwood ranges from light to dark reddish-brown
  • Straight to interlocked grain
  • Medium to coarse texture
  • Low bending strength
  • Medium crush strength
  • Very low stiffness and resistance to shock
  • Used for high-class furniture and cabinet making, reproduction furniture, boat interiors, carving, turnery, and molding
Southeastern States

Virginia, North Carolina, South Carolina, Georgia, and Florida.

Southern States

Alabama, Mississippi, Texas, Louisiana, Arkansas, and Tennessee.

Southern Yellow Pine

A species group composed of primarily of Loblolly, Longleaf, Shortleaf, and Slash Pines. Various subspecies are also included in this group. This group refers to the Southeastern United States, from Texas to Virginia.

Spacing Control

The act of creating, within the limits of the existing stand, a uniform distribution of trees that provides optimum growing space for each tree by eliminating overcrowding. As a result, tree diameter growth is increased and the time required for the forest to reach harvestable size is decreased.

Spade Bit

These are an inexpensive bit, suitable for general use, they get their name from their shape.


The width of a building or overall length of a truss.

Spanish Cedar
  • Pale pinkish-brown heartwood
  • Straight grain, sometimes interlocked
  • Moderately coarse texture
  • Strong in relation to its weight
  • Easy to work with hand and power tools
  • Durable
  • Premier wood used for cigar humidor interiors, furniture, cabinets, paneling, flooring, boat building, clothing chests, decorative veneers, and plywood.
Spar Tree

A tree or mast on which rigging is hung for one of the many cable hauling systems.


A category of biological classification; a class of individuals having common attributes and designated by a common name. “Species” is always properly used with the “s” when referring to trees or other biological classifications.

Specific Adhesion

Adhesion between surfaces that are held together by valence forces of the same type as those that give rise to cohesion.

Specific Gravity

The ratio of the weight of wood to an equal volume of water. The higher the specific gravity, the heavier the wood.


A defect that’s caused by a fungus living in a tree, which appears as small white pits of spots.

Speed Square

The rafter angle square is a triangular-shaped measuring tool used to draw straight lines on lumber to be cut, or to lay out angles for roofs, stairways, decks and other general construction. The tool is marked with degree gradations for fast layout and cutting of lumber without performing complex trigonometry calculations.


A narrow, turned piece of wood.


An attractive dark brown or black stain in some woods caused by decay. A change in the texture, strength and color of wood caused by colonies of fungus growing within the dead wood.


One who joins two pieces of cable together by intertwining the wire strands.


A separation of wood fibers that extends completely through a piece of lumber, usually at the ends.


A thin strip of wood fitting between two grooves to make a joint.


Used to shape curved surfaces, consists of a blade fastened between two handles, blades come in straight concave and convex curves.


To place a truck or trailer in position for loading.

Spray Gun

A cloud of mist of fine liquid particles, as of water from breaking waves.


The quantity of adhesive per unit joint area applied to an adherent.

  • Single Spread – Refers to application of adhesive to only one adherent of a joint.
  • Double Spread – Refers to application of adhesive to both adherents of a joint.
Spring Steel Alloy

A type of hardened steel that has both hardness and yield strength.


Tool with a narrow-shaped, curved blade used in removing bark by hand. This is also called a barking iron.

Spur Road

A road that supports a low level of traffic, such as a level that would serve one or two settings. Little or no engineering design work is needed to build it.

Spruce-Pine-Fir (SPF)

Canadian woods of similar characteristics that have been grouped for production and marketing. The SPF species have moderate strength, are worked easily to take paint readily and hold nails well. They are white to pale yellow in color. The largest volume comes from eastern Canada, where the principal species in the group are: Black Spruce, Red Spruce, Jack Pine, and Balsam Fir. The principal species of the group originating in Western Canada are Alpine Fir, Engelmann Spruce, Lodgepole Pine, and White Spruce. Some lumber production in the New England State also is marketed as Spruce-Pine-Fir (south).


An instrument used to lay out or test right angles, with two arms at 90 degrees to each other; the longer and wider arm is the blade, the shorter narrower arm is the tongue.

Squeeze Out

Bead of adhesive squeezed out of a joint when pressure is applied.

Stacked Dado Head

style of dado cutter has two outside saw blades, using a combination of chipper blades and shims between them the width of the dado is set.


A mobile machine for unloading and stacking or decking logs using the forklift principle and curved top clamps. A heavy-left machine similar to a front-end loader, with forks and clamps capable of handling and loading logs.

Staggered Setting

Cleat-cut settings separated by uncut timber.


A discoloration in wood caused by a chemicals, fungus, or minerals. A dye or pigment used to discolor wood.

  • Blue Stain – A bluish discoloration of the sapwood caused by the growth of certain dark-colored fungi on the surface and in the interior of the wood.
  • Brown Stain – A rich brown to deep chocolate-brown discoloration of the sapwood of some pines caused by a fungus that acts much like the blue-stain fungi.
  • Chemical Brown Stain – A chemical discoloration of wood, which sometimes occurs during the air drying or kiln drying of several species, apparently caused by the concentration and modifications of extractives.
  • Sap Stain – A discoloration of the sapwood caused by the growth of certain fungi on the surface and in the interior of the wood; made possible by the same conditions that favor the growth of other fungi.
  • Sticker Stain – A brown or blue stain that develops in seasoning lumber where is has been in contact with the stickers.

In Silviculture and management, a tree community that possessed sufficient uniformity in composition, constitution, age, spatial arrangement, or condition to be distinguishable from adjacent communities. This tree community forms a silvicultural or management entity; for example, a sub-compartment. Both natural and artificial crops are included, and there is no connotation of a particular age. In Mensuration, the amount of timber and/or fuelwood standing on an area, generally expressed as volume per unit area; for example, board feet per acre or cubic meters per hectare. In the United States, growth of trees on minimum of one acre of forest land that is at least 16.7 percent stocked by forest trees of any size.

Stand Condition

The general health of a stand of trees reflected by its development relative to the site potential. A good stand condition refers to a fully stocked stand that is producing fiber at a high rate based on specific site conditions such as moisture, soil quality, and other biological variables.

Stand Density

The number of merchantable trees per acre. A quantitative measure of tree stocking frequently expressed in terms of number of trees, basal area, or volume per unit area.

Stand Improvement

Measures such as thinning, release cutting, girdling, weeding, or poisoning of unwanted trees to improve growing conditions.

Stand Size Classes
  • Non-stocked Areas – Commercial forest land on which the stocking of growing-stock trees is less than 16.7 percent.
  • Poletimber Stands – Stands at least 16.7 percent stocked with growing-stock trees, with half or more of this stocking in sawtimber and/or poletimber trees. Stocking of trees exceeds that of sawtimber stands.
  • Sapling-Seedling Stands – Stands at least 16.7 percent stocked with growing-stock trees, with saplings and/or seedlings comprising more than half of this stocking.
  • Sawtimber Stands – Stands at least 16.7 percent stocked with growing-stock trees, with half or more of this stocking in sawtimber or poletimber trees. Sawtimber stocking at least equals poletimber stocking.
Stand Table

A table showing the number of trees by species and diameter classes, generally per unit area of a stand. Such data may be presented in the form of a frequency distribution of diameter classes.


A tooth form that has evenly spaced teeth, deep gullets, and a zero-degree rake angle.

Standing Line

A fixed cable that does not move during logging operations; for example, a skyline anchored at both ends.

Static Bending



The main body of a tree from which branches grow. Used loosely to refer to trees. For example, stems per unit area.


Wood from the main part of a tree, not from the branches, stump, or root.


A piece of short pulpwood.


A ¾” to 1” wood strip that is inserted between stacks of green wood and spaced between 16” to 24” to allow air to flow through the stack to ensure proper drying.

Sticker Stain

Sometimes called shadow, it’s a stain that forms under the stickers in a stack of drying wood.

Stiff Leg

A loader with a boom that does not swing.


The decorative end of a chamfer.

Story Stick

A “story stick” or “story pole” is a scrap strip of wood used to record dimensions for a project on site, then the dimensions are used in the ship to build the project. This method reduces the chance or error due to misreading numbers etc.


A term applied to the axial cells and rays in wood when these are arranged in horizontal series on tangential surfaces.


A short cable with a loop at each end.


A stripe of ribbon pattern that occurs when woods with interlocked grain, which slopes in alternate directions, are quarter-sawn.


A handle of a peavey or cant hook.


The degree of utilization of land by trees. Measured in terms of basal area and/or the number of trees in a stand compared to the basal area and/or number of trees required to fully utilize the growth potential of the land. A stocking percent of 100 indicates full utilization of the site and is equivalent to 80 square feet of basal area per acre in trees five inches in D.B.H. or larger. A stocking percent of 100 in a stand of trees less than five inches in D.B.H would indicate that the percent number of trees is sufficient to produce 80 square feet of basal area per acre when the trees reach five inches D.B.H. A stocking percent over 100 is fully utilizing the site.

Stocking Classes
  • Fully Stocked Stands – Stands in which the stocking of trees is from 100 to 133 percent.
  • Medium Stocked Stands – Stands in which the stocking of trees is from 60 to 100 percent.
  • Non-Stocked Areas – Commercial forest land on which the stocking of trees is less than 16.7 percent.
  • Over-Stocked Stands – Stands in which the stocking of trees is 133 percent or more.
  • Poorly Stocked Stands – Stands in which the stocking of trees is from 16.7 to 60 percent.
Storage Life

The period of time during which a packaged adhesive can be stored under specific temperature conditions and remain suitable for use.

Straw Drum

A small drum on a yarder that handles the straw line.

Straw Line

A light-weight line used to change main skidding lines and tackle in cable yarding systems.


The ability of a member to sustain stress without failure.

Strength Ratio

The hypothetical ratio of the strength of a structural member to that which it has if it contained no strength-reducing characteristics.

Stress Wave Timing

A method of measuring the apparent stiffness of a material by measuring the speed of an induced compression stress as it propagates through the material.

Stress Skin Construction

A construction in which panels are separated from one another by a central partition of spaced strips with the whole assembly bonded so that it acts as a unit when loaded.


A timber or other support for cross members in floors or ceilings.

Structural Composite Lumber (SCL)

Wood elements glued together to form products that are similar in size to solid sawn lumber.

  • Laminated Strand Lumber (LSL) – Similar to oriented strand lumber with somewhat longer strands.
  • Laminated Veneer Lumber (LVL) – Structural composite lumber manufactured from veneers laminated into a panel with the grain of all veneer running parallel to each other. The resulting panel is ripped to common lumber dimensions.
  • Oriented Strand Lumber (OSL) – Structural composite lumber made from wood strand elements similar to those used in oriented strand board. The strands are oriented primarily along the length of the member.
  • Parallel Strand Lumber (PSL) – Structural composite lumber made from high aspect ratio wood strand elements manufactured from veneer oriented primarily along the length of the member. It is manufactured in billets and cut to lumber dimensions.
Structural Integrity

A structure uncompromised ability to safely resist the required loads.

Structural Timbers

Pieces of wood of relatively large size, the strength or stiffness of which is the controlling element in their selection and use.


A short timber placed in a structure either diagonally or vertically; designed to act in compression along the direction of its lengths.


A framing member, usually cut to a precise length at the mill and designed to be used in framing building walls with little or no trimming before it is set in place. Studs are most often 2x4s, but 2x3s, 2x6s, and other sizes are also included in the stub category; studs may be made of wood, steel, or composite material.


The value of timber as it stand uncut in the woods.

Stump Jumper

A heavy plate underneath a skidder that protects the back housing from contact with high stumps.

Stump Pull

Slivers of wood remaining attached to the stump after a tree is felled; the slivers are considered as having been pulled from the butt of the log.


Wood cut into short lengths and piled near the stumps.

Stumpwood Chips

Chips manufactured from Stumpwood.

Style or Stile

A vertical member of a door's framework attached to the horizontal rails.


A material upon the surface of which an adhesive containing substance is spread for any purpose, such as bonding or coating.


The deck construction that is located below, and supports the deck boards and railing system. Components include joists and hangers, ledgers, rim joists, beams, posts, anchors, and footers.


Logging arch equipment with wheels instead of crawler tracks and towed behind a skidding machine.

Summer Beam

A major horizontal timber which spans the girts or plates.


One of the four major crown classes, specifically trees with crowns entirely below the general level of the crown cover receiving no direct light either from above or from the sides. This is also known as overtopped.

Surfaced Checks

A drying defect that occurs when the surface dries too quickly in relation to the core.

Surface Inactivation

In adhesive bonding to wood, physical and chemical modification of the wood surface that result in reduced ability of an adhesive to properly wet, flow, penetrate, and cute.

Surfaced Lumber

A piece of wood that has been planed smooth on one or more surfaces.

Surface Tension

The force per unit length acting in the surface of a liquid that opposes the increase in area of the liquid.


The way a piece of lumber has been prepared at the lumber mill.

Sustainable Forest Initiative (SFI)

This is a program that was established in 1994 and currently certifies over 152 million acres in the United States and Canada. It is based on the premise that responsible forest practices and sound business decisions can co-exist. Independent certification bodies evaluate planning, procedures, and processes in the forest and in wood processing operations.

Sustained Yield

Timber yield that a forest can produce continuously at a given intensity of management. Sustained yield management therefore implies continuous production planned to achieve a balance between growth (increment) and harvest at the earliest practical time.


An area saturated with water throughout much of the year, but with the surface of the soil usually not deeply submerged. This is usually characterized by tree or shrub vegetation.

Swamp Buggy

A Skidder equipped with high floatation tires.


A gradual bend in a standing tree or in a log, pole, or piling.


Trees greatly enlarged at the base.


Universal joint used in rigging to prevent lines from twisting.

Symmetrical Construction

Panels in which the plies on one side of a center ply or core are essentially equal in thickness, grain direction, properties, and arrangements to those on the other side of the core.

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