A Glossary of Building Terms

We recognize that building a custom home can be an overwhelming task, but our goal is to make it as easy and informative as possible. In doing so, we have prepared a glossary of common building terms that will assist you with some of the terminology you will encounter. If you have any questions, please don’t hesitate to contact us at any time.

A Glossary of Building terms

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Adhesive – High-performance glue used to adhere wood or other building components. May be used as a sealant in log homes.

Air-Dried – Logs are considered air-dried when they have been dried in producers’ yards or warehouses for six to 24 months.

Anchor Bolt – A steel bolt which is embedded in the concrete foundation of a structure and used to anchor the sill plate.

Angle Brace – Any timber bracing a corner at an angle across that corner. Also called a knee brace.

Angle Iron – A length of steel or iron bent at a right angle along its long dimension, used as a support or structural framework. Frequently used to support masonry over an opening.

Awning window – Type of window that opens out from the bottom.

Backfill – Placement of excavated or imported soil or fill around the base of a home’s foundation.

Base course- The first or bottom course of logs or masonry blocks in a wall.

Bay window – A window or grouping of windows that protrudes outside of a home’s exterior wall.

Beam – Horizontal member of a home’s structural frame, used to support vertical loads.

Bearing wall – A wall supporting a vertical load.

Birds mouth – A ‘V’ shaped notch cut into the base of a rafter that allows the rafter to sit flat on the wall or the plate.

Blueprints – One name for the construction drawings used to build a home.

Borate – Chemical used as an insecticide to inhibit insect infestations in wood.

Buck – Frame of dimensional lumber set into a log wall and used to frame windows and doors.

Butt and pass corner – A form of butt corner where one log end extends beyond the intersection with the log in the opposing wall. In this design, every other log extends past the corner, giving a home that distinctive log home look.

Butt joint – Fastening together of two shorter logs end to end to create a longer timber that will span the length of a wall.

Cambium layer – A thin-walled layer of cells beneath the inner bark of a tree, made of living cells that continually divide and account for the tree’s growth. When this is left in tact and the bark is removed, it will dry to a shiny dark finish.

Cantilever – A beam or slab projecting a substantial distance beyond its supporting post or wall; a projection supported at only one end.

Cape Cod – A residence with two levels of living area (1.5-1.75 stories) may be characterized by a steep roof slope and may have dormers. The area of the second floor is usually 40% to 75% of the ground floor area.

Casement window – Style of window hinged on its sides to allow it to swing open vertically.

Cat Face – An indentation on the surface of a tree, usually caused by injury at some earlier date.

Caulking – The most common type of sealing material used on log homes, available in five different formulations: acrylic, butyl, oil-base, silicone and urethane.

Check – Crack-like opening that forms in a log as it shrinks and dries.

Chinking – Historically a mortar-based material used to seal the gaps between logs; modern chinking resembles mortar, but remains soft and pliable to move with the logs. Chinking is often used as a visual accent to log walls.

Close grain – Wood with close grain has narrow, inconspicuous annual growth rings and/or closely spaced pores.

Coarse grain – Wood with coarse grainhas wide, conspicuous annual growth rings.

Collar tie / Collar beam – A horizontal timber which ties two opposite pairs of rafters together near the middle to reduce sagging or spreading.

Colonial – A type of home design typified by two stories with a central hall and symmetrical window placement.

Compression / compression recovery – In comparing foam gasketing materials as log wall sealants, compression indicates how easy or difficult it is to compress the foam between log courses. Compression recovery indicates how completely the foam recovers to its original height after extended compression.

Conductivity – An inverse measure of the insulating value or resistance to heat flow of a material. The lower the conductivity, the higher the insulating value. Usually expressed as a number of Btu (British thermal units).

Cope – A notch in a log which is cut and rounded to fit over another log.

Countersink – To cause the head of a bolt or spike to be below the surface of the wood into which it is embedded.

Cove – A shallow, round shaped groove cut into the underside of a log.

D-shape – A style of logprofile in which one side of the log is left rounded, while the other is flattened. Allows for flat interior log walls that resemble paneling.

Dead Load – The accumulative weight of all structural members, the fixtures and the permanently attached equipment of the structure and its foundation.

Dormer – A structure that protrudes from a sloping roof and contains a window or group of windows.

Double-hung window – A window style with sashes that slide vertically and allow opening from the top and bottom.

Dovetail corners – A style of interlocking corner created when the end of each log is cut into a fan-shaped wedge that is narrower toward the middle of the log. Most often used with square or rectangular logs.

Dowel – Wooden peg used to hold two pieces of wood together.

Drawknife – A two-handled blade that is used to peel bark from logs.

Drip Edge – The metal or vinyl projection along the eaves or rakes of a roof that allows water to run off or drip away from the underlying construction.

Eave – The lower or bottom edge of a roof which projects beyond the face of the walls

Early wood – In a tree’s annual growth ring, the portion formed in the spring, which is light in color.

Easement – Right that one party owns to a portion of another party’s property for a limited use. For instance, a utility company might own the right to cross a section of land owned by a private owner.

Expansion joint – A joint which permits expansion without doing damage to the structure.

Fascia – The trim board which usually covers the exposed ends of the rafters or overhang.

Fasteners – Hardware used to fasten logs to one another and make a log wall more rigid.

Fixed glass window – Also called a picture window, a window that does not open.

Flashing – A sheet material, such as metal, that bridges two building elements and prevents water from entering.

Foam gasket or tape – Putty or rope like extrusions of PVC foam that are used to prevent drafts or moisture from seeping between logs.

Footing – The base of the foundation that supports the foundation walls.

Fungi – Plants that cause decay as they feed on the substances found in wood.

Fungicide – Chemical agent that inhibits the growth of fungi on wood.

Gable – The triangular portion of the wall, between the enclosing lines of a sloping roof.

Gable roof – A sloping roof which forms an ‘A’ shape.

Gambrel roof – A roof where each side has two slopes; a steeper lower slope and a flatter upper one; a ‘barn roof’. A four-pitched roof traditional on Dutch style barns.

General contractor – A professional who oversees a construction project, including the scheduling, supervision and payment of subcontractors.

Girder – A horizontal structural member that supports joists.

Girt – A major horizontal member that connect posts.

Grain – Wood’s grain usually refers to the quality of a log’s annual growth rings or to the arrangement of the wood fibers in a log. Annual rings are said to have either a fine or coarse grain.

Green wood – Wood or logs that are used within weeks or sometimes even days of having been cut.

Half-lap – A type of joint in which two timbers are lapped or let into one another

Half logs – Logs that are sawn in half lengthwise and applied to a conventional stud-framed wall to create a wall that looks like full logs.

Hand-hewn – Logs that has been squared through the use of hand tools such as an adze or ax.

Header – Built-up horizontal member of a home’s frame that tops a window or doorway.

Heartwood – The portion of the tree contained within the sapwood; this term is sometimes used to mean the pith. The heartwood is dormant and unnecessary for the tree’s continued life; the living part of the tree is contained in its outer parts. Usually slightly darker in color and more resistant to decay than sapwood.

Hip – The sloping ridge of a roof formed by two intersecting roof slopes.

HVAC – Heating, ventilation and air-conditioning systems.

I-beam – A steel beam with a cross section that resembles the letter ‘I’. Truss Joist (TJI) floor joists often referred to as I-joist.

Interlocking corner – A more complex type of log home corner in which wood is removed from the four sides of a log, leaving a recessed area that locks into a similar area on the intersecting log and holds both logs rigidly in place in all directions.

Jack Rafter – A short rafter which extends from the roof ridge to a valley rafter or from the wall plate to a hip rafter

Joist – A horizontal beam that supports the weight of a floor or ceiling.

Joist hanger – A metal support for the ends of joists; typically a Simpson hanger.

Kerf – The groove left in a piece of wood by a saw cut.

Kerf Cut – When building with green logs, a longitudinal kerf shall be cut at the top of each wall log. The kerf must be deep enough to promote checking. At least ¼ of logs average dia. And not more than ½ the logs average dia. Kerf shall be continuous between notches and shall start 6” from the edge of all notches.

Kiln-dried – Logs that are force-dried in a kiln to less than 15 percent moisture content. The logs are subjected to heat and humidity in stages to both dry them and reduce the side effects of drying, such as checking, twisting and warping.

King Post – A vertical support which transfers weight from the ridge beam to the end walls or the joists.

Knee Brace – A small timber which is framed diagonally between a post and beam.

Knot – A portion of a branch or limb that is incorporated in a piece of lumber. Knots interrupt the direction and flow of the wood’s fibers and can affect the wood’s strength.

Lag screw / bolt – A heavy screw for wood with a bolt head.

Laminated logs – Built-up timbers that are manufactured by gluing, or laminating, dimensional lumber together, then shaping the timbers into traditional log profiles.

Lap siding – Wood siding material that has a flat exterior surface, characterized by boards that widen at their base.

Lateral Groove – A longitudinal groove cut into the underside of a log enabling that log to fit over the top of another log.

Latewood – In a tree’s annual growth ring, the darker portion, which is formed later in the growing season. Latewood is generally denser and stronger mechanically than earlywood.

Linear footage logs – Logs that are delivered to a home construction site without pre-cutting of the logs to any specific length.

Lintel – A horizontal member of a home’s frame that forms the top of a window or door opening.

Log scribe – Tool used to mark the shape and outline of one log onto the log that will sit above it in a log wall.

Log siding – Siding material made up of logs that are sawn into thin strips, which still retain the curved shape of the log.

Mildewcide – Chemical agent in a wood preservative or finish that inhibits the growth of mildew.

Moisture content – The amount of water present in a log, measured in terms of the weight of the water in respect to the weight of the log.

Mortise – A square or rectangular slot cut into a log, timber or board into which another member, usually called a tenon, will fit.

Mortise and tenon joint – A joint in which a projection (tenon) of one timber is inserted into a slot (mortise) of another timber.

Notch – A recess cut into a log to accept another log intersecting it at an angle.

Blind notch – A notch which does not extend completely through a log.

Boxed lap notch – A notch cut squarely into part of each timber.

Dovetail notch – Log ends cut into a fan appearance resembling a dove’s spread tail.

Mitered lapped notch – Notch which has a 45 degree slope on the sides if a square notch.

Round notch – A notch in which the profile of the log exhibits the shape of a partial circle on the underside.

Saddle notch – notch which is triangular in profile.

Square notch – has the appearance of a round notch on the exterior but inside has a square interlocking lap.

Old growth – A forest in which trees have grown in active competition for sunlight and moisture. Old-growth timber is usually straight and relatively free of knots.

Outrigger – A log which sits atop cantilevered logs on the eave walls and is parallel to and extends out beyond the plate logs. It is to this beam that the roof framing is attached.

Overhang – The portion of the roof structure that extends beyond the exterior walls of a building.

OSB – Oriented strand board; an engineered wood product created by laminating shreds of wood into sheets.

Partition wall – A wall that separates spaces in a home. In log homes, partition walls typically are built using conventional stud-frame construction, rather than logs.

Passive solar heating – A system that uses certain building materials (such as log or masonry) to collect and release energy from solar radiation.

Peg – A wooden dowel

Percolation (or “perc”) test – Test performed to measure how porous soil is.

Piece en piece – A style of building in which vertical support posts form the main structure of a home with short lengths of logs forming the wall panels in sections between posts.

Pier – A type of support used as a foundation, which consists of vertical poles or columns set on footers.

Pitch – The slope or angle of a roof. Generally expressed in inches of vertical “rise” per 12 inches of horizontal distance “run”. (example: written as 4/12 or said as ” 4 inch rise per 12 inch run ” or simply ” four twelve or four in twelve “)

Pith – The soft tissue about which the first wood growth in a tree takes place.

Plate / plate log – A horizontal member of the frame of a home on which the rafters rest. The log at the top of a wall that supports the roof.

Post and beam – Type of construction characterized by exposed timbers that form a structural frame, vertical posts supporting horizontal members and beams. The timbers may be joined by traditional carved wood joinery or by metal hardware.

Pressure treating – A process in which wood is saturated with a preservative under pressure, allowing the preservative to be absorbed deep into the wood’s fibers.

Purlin – A roof support beam that runs parallel to the ridge beam and the long sides of a home and is placed between the plate log and the ridge beam.

R-value – A measure of resistance to the flow of heat. Higher R-values indicate a material’s greater ability to insulate.

Racking – A reaction to lateral forces pushing horizontally on a wall, racking causes walls that are not rigidly fastened to become deformed.

Rafter – Structural members of a roof that support the roof load and run from the ridge to the eaves (overhang).

Saddle – The lower cut in a notch and saddle joint. The log is cut on an angle on each side so that the surface almost comes to a point at the top of the log wall.

Salvaged wood – Typically large, old-growth timbers that are reclaimed from old structures and reused in new construction.

Sap stain – A fungus that discolors the sapwood, usually during storage and air-drying. It can be brown, steel gray, black or blue, but blue stain is the dominant type. May cause a permanent blemish that cannot be removed from the surface.

Sapwood – The wood formed just inside a tree’s cambium layer. May comprise the first one to three inches of radial thickness beneath the bark and contains mostly living cells that carry sap from the roots to the leaves.

Scribe – The process of cutting one log to match the contours of another for a tight log to log fit.

Screwjack – A device which may be adjusted to allow for the settlement in log walls. Typically consists of (2) 6”x6”x1/2” steel plates complete with (4) 4”x3/8” lag bolts and a 1” diameter redi rod with an adjustable nut and washer at the bottom.

Sealants – Material used to ensure a weather tight seal between the logs stacked in a wall.

Second growth – A second-growth forest is a newer, managed forest grown on land that was previously cleared. Most of the lumber used in log home construction comes from second-growth forests.

Seismic load – A measure of seismic pressure that must be taken into account for a home to meet building codes. Homes built in earthquake-prone areas will be required to withstand greater seismic pressures.

Setbacks – Minimum distance required by local zoning ordinances between a property line and the edge of a building.

Settling – Loss of wall height by shrinkage and compression. The movement of walls that occurs over time and with the shrinkage of logs as they lose their moisture.

Shear – A lateral force that can affect horizontal log walls by causing the logs to slide along one another. A log wall that’s properly fastened will be more rigid and will resist shear force more efficiently.

Shed roof – A roof containing only one sloping plane, typically a shallow pitch; has no hips, ridges, valleys or gables.

Shrinkage – The decreasing in size of a log as it loses some of its moisture content over time.

Sill – A horizontal member of a home’s frame that forms the base of a window or door.

Sill log – The base log which sits upon the foundation.

Skip peel – A method ofremoving bark from a log that leaves dark patches of the cambium layer visible on the surface of the log.

Snow load – A measurement of the weight of the heaviest snow load likely to occur in a two-month period in a certain region. Most roof systems are designed to carry a dead load of 20 pounds per square foot. In localized areas of some snow-belt regions, snow loads of 150 pounds per square foot are not uncommon.

Soffit – A material, which covers the underside of an overhang.

Spiral grain – Irregular grain pattern formed in a tree that has bent or twisted to seek out sunlight. Spiral grain is undesirable in a log, as it may lead to twisting as the wood dries.

Spline – A 1 to 2 inch high strip of fiberboard or plastic about 1/8 inch thick, inserted into the spline groove on a log to create a physical barrier to air and water infiltration between logs stacked in a wall.

Splice – A joint of two logs end to end.

Standing dead – Used to describe standing trees that have been killed by fire, insects or some other cause. Wood in these trees is generally not affected by whatever killed them.

Starter strip – Generally a 1 by 2 inch wood strip nailed to the subfloor, over which the first log is set, creating a seal between the log wall and the subfloor.

Structural insulated panels – Building panels made up of a layer of high-density foam sandwiched between two layers of sheet material such as plywood, tongue-and-groove paneling or oriented strand board (OSB). Also known as stress skin panels.

Subcontractor – Tradesperson who performs a specific task in a construction job, such as installing plumbing, laying carpet or painting, under the supervision of a home owner or general contractor.

System built – Home built using a package of manufactured components.

Swedish cope – Log building method in which a half-moon shaped groove is chiseled out of the length of a log, allowing it to straddle the rounded surface of the log beneath it in a wall.

Thermal mass – A property of wood that slows the transfer of heat through a log wall due to the high heat retention capacity of the wall mass.

Thermal resistance – The insulating value of a material. Usually expressed as an R-value, resistance varies among wood species and depends on the density and other qualities of the wood.

Through-bolts – Threaded metal fasteners, 1/2 to 3/4 inch thick and either 2, 4 or 8 feet long. A length of through bolt is often connected to anchor bolts embedded in the foundation. When the desired length is reached, a washer and nut are added and tightened to pull the wall together.

Timber frame – Type of traditional construction characterized by exposed timbers that form a structural frame. The timbers are joined by traditional carved wood joinery.

Tongue and groove (T&G) – Lumber with a small groove down one side of each board and a protruding piece (tongue) on the other side that fits into the groove when the boards are installed.

Trim – Woodwork, often detailed, that finishes off certain elements in a home, such as windows, doors, stairs and cabinetry.

Truss – Triangular-shaped construction element that supports a home’s ceiling or roof, and allows for an open space below, unimpeded by posts.

UV blocker – Chemical agent added to wood preservative or finish to inhibit the sun’s graying affect on wood.

Vapor barrier – A waterproof material or film placed between a heated area of the home and an area that is not heated to prevent moisture from seeping between the two areas.

Wane – The bark that remains on an edge of a milled log created by the lack of wood on the edge or corner.

White rot – Along with brown rot, a major category of decay caused by fungi. Results in the wood losing its color and appearing whiter than normal. Wood affected by white rot will not crack against the grain and will only shrink and collapse when it is severely degraded.
Wind load – Measure of the force of the wind as it affects the structural integrity of a house. Homes built in hurricane-prone areas are required by code to withstand higher winds.

Wood preservative – Specialized finish formulated to protect wood from the deteriorating effects of wind, rain and sunlight, and attacks by fungus, mold, mildew and insects.

Zero-clearance – The lack of a need for a specified distance between a well-insulated heating unit or metal wood burning fireplace and a combustible surface. A Self-contained fireplace unit that can be placed in close proximity to other combustible building materials.

Resources:

International Log Builders Association – “Log Homes – From Land to Lockup”.

The Log and Timber Authority

Home Buyers Publications

Wikipedia ‘The Free Encyclopedia’ – http://en.wikipedia.org

Webster’s New Word Dictionary