Building Terminology


Air-dried Logs or Lumber: Logs or lumber which has been left to dry down to a point in which the moisture content is in equilibrium with the temperature and relative humidity of the atmosphere or to a determined moisture content, an alternative to kiln dried logs or lumber.

ACQ Pressure treated: (Alkaline Cooper Quaternary) Lumber that is first incised, then undergoes a process that forces Cooper and Quaternary chemical preservatives into the wood under a vacuum and high pressure. The preservatives help protect the wood from infestation by termites, other insects and decay.


Backfill: Replacement of excavated earth against the foundation wall of a basement or crawl space. This is done after the first floor subfloor and rough framing is completed.

Beam: A structural member supporting a load applied transversely a horizontal weight supporting member of a structural frame to it.

Bearing: Area of structural support, as in a bearing wall, partition, post or beam.

Bird’s mouth: The cut usually located near the end of tailed rafters. The bird’s mouth cut rests on the top of the building exterior wall, on a supporting beam or plate. Should not be used at upper or intermediate bearings.

Blanket Insulation: Insulation in long rolls usually 15” or 23” wide for full-length placement between studs, joist or rafters, usually composed of mineral fiber (Glass wool).

Blue Stain: Is caused by microscopic fungi that infect the sapwood of trees, using the sapwood as a food source. Blue stain fungi typically will not infect the heartwood of the tree. Blue stain causes a blue or gray discoloration of the wood and will not affect the strength of the wood or cause decay.

Built Up Roof: A roof system where insulation is installed over a finished sub roof (usually 2X6 T&G), which is attached to a structural timber or purlin framework.

Building Wrap (House Wrap): A weatherization material used to wrap the exterior structure between the wall sheathing and finish materials such a siding. Provides an exterior moisture and air barrier and allows the interior moisture vapor to transfer out through the wall.

Bunking: Material used to prevent building materials from direct contact with the ground.

Butt Joint: The point at which two logs on the same course join end-to-end.


Casing: Trim around window or door opening.

Casement window: A window hung vertically, hinged on one side so that it swings inward or outward

Cants: Cants are produced from green logs. The logs are stripped of bark and sawn into 4- sided timbers. The cants are then used to make dimensional lumber, logs or log siding.

Caulking: Putty like mastic material used to fill and seal cracks and crevices. Usually this is applied in a color that matches the wood so that it is not prominent when viewed from a distance.

CNC Machine: Computer Numerical Controlled milling machines used for precision milling. Footprint Log Homes are 100% pre-cut and pre-drilled (for lag construction) using this type of machinery.

Chamfer: A shallow cut, edge or groove made in wood, usually at an angle of 45 degrees.

 Chase: Raceway. Channel in building to carry electrical or mechanical lines.

Checking: Cracks in wood, naturally present due to the drying process.

Chinking: The exposed caulking used between rows of stacked logs. Most often used in log systems where rows of logs do not bear directly on the row below, but are separated by a space. Traditional chinking is mortar-based. Modern synthetic chinking, manufactured to look like traditional chinking, is similar to caulk but with greater density, flexibility and durability.

Clad: Typically refers to “window clad” which is the covering of the exterior wood frame of a window. Materials can be vinyl, aluminum, fiberglass, etc.

Cope: The concave curve on the bottom of a round milled log that allows it to sit snuggly over     the log below.

Corbel: A structure of dimensional lumber or log normally in somewhat of a triangular shape used as a gusset to support eves without sufficient support from lookouts…an offset cantilevered support of wood or masonry.

Corner Styles or Configurations:

 Dovetail: This corner system is used mainly with square or rectangular logs. The end of each log is cut to produce a fan-shaped wedge. As the logs are stacked the ends of one wall’s logs lock into the perpendicular logs drawing the corner tighter as additional weight (load) is

  • Notch and pass corners: This corner system is formed when one log stops where it meets the intersecting log, and the other log extends past the
  • Saddle-notch: This corner system is also known as saddle cope or round They get their name from the saddle shaped notch cut into the bottom of each round log. The notch on the bottom of the top log straddles the top of the log coming from the perpendicular wall. Both logs then extend past the corner.
  • Corner Board: With this corner system the logs are notched on the exterior to receive a formed piece of flat material at the corner. No logs extend past the corner.
  • Corner Post: With this corner system the logs butt into a corner post/log. No logs extend past the

Corner notch: A notch cut into the log that interlock logs at a corner intersection. There are a number of notch styles used in constructing log homes. The type of notch will determine the appearance of the log corners.

Composite Decking: Deck boards manufactured with wood fiber and plastic or other materials. There are a variety of manufactures and grades of composite decking. Consult your builder or local lumber yard for more information.

Course Log: All of the logs located at any particular height within the log wall, i.e. 1st course, 2nd course, 3rd course, etc. This is also known as a “round” by the Canadian Manufacturers.

Crawl Space: Formed area under a home of sufficient depth to allow a person to repair or maintain systems.


D-Log: A type of log profile where the milled log is a “D” shape, where the outside of the log is rounded and the inside is flat.

Decay Resistance: The ability of wood to resist the effects of exposure to air, water and the ultraviolet rays in sunlight. The different species of wood vary in their resistance. However, none are completely decay-proof.

Decking or Sheathing: Sub-floor material such as plywood, particle-board, O.S.B. 2X6 Tongue and Groove, which are applied directly to floor support members.

Door Buck: A door frame of rough material to which the finished doorframe is attached

Dormer: A constructed projection from a roof plane used to provide additional interior space. Dormers typically can be shed or gable styles.

Dovetail Log Connection or Butt Joint: A milled fan shaped wedge and corresponding fan shaped pocket used to interlock logs together for a superior connecting strength and an air- tight seal. The exclusive standard feature on all Footprint milled Log Homes is a dovetail butt joint on log connections.

Double Hung Window: A style of window with two vertically sliding sashes, both of which can move up or down.

Drawknife: The tool consisting of a sharp blade set between two handles. Users pull the blade toward their bodies along the log or timber’s surface to peel bark or wood.

Drip Cap: A metal or wood molding or flashing placed over a window or door to enable the water to run off the top of the unit.

Dry-In: A term used to define the stage of construction when the interior of the structure is protected by the weather. (weather tight). Typically the windows, doors, ice and water barrier have been installed. Also referred to as “Lock up” in Canada


Eave: The edge of a roof over hanging the wall at the tail or bottom of the rafter.

Egress Window: A style of window that is required in every bedroom if there is no exterior door and required in a bedroom that is located in a basement. Check your local building codes to find out the minimum size required and locations for egress windows.

Energy Star Rating: Energy Star is a government-backed labeling program that helps people and organizations save money and reduce greenhouse gas emissions by identifying factories, office equipment, home appliances and electronics that have superior energy efficiency.

Engineered Plans: A floor plan design that is evaluated by a licensed engineer for structural integrity. Each Log Home package is evaluated and approved by a licensed engineer for your State or Province.

Exposure: The effect of wind speed on a structure. Often referred to as wind load or wind shear. The numbering and lettering designations vary between states.


Fascia: A flat board used to cover rafter/truss ends at the eaves and the rake of the roof.

Fasteners: Hardware used to secure logs and timbers. Types of fasteners include screws, spikes, wooden pegs, through-bolts and metal brackets.

Foam Gasket: A compressible foam material that is typically water resistant, used between logs and other building components to prevent air and water infiltration. Tongue and groove log systems use foam gaskets to seal the joint between adjacent rows of logs.

Footing: The sub-grade portion of a foundation that the foundation walls or deck/porch posts are set on.

Foundation: The vertical load bearing wall structure which supports the first floor construction and is partially located below grade to the footings. Usually made of poured concrete, concrete block or pressure-treated wood.

First Floor System (Sub Floor): The structural floor system that is constructed on the foundation wall. Includes the sill plate, floor joists, rim board and OSB or plywood decking supported by a load bearing wall or beam and supports in the basement or crawl space.

Fixed Glass: A glass window that does not open and is typically used in a gable wall.

Flashing: A waterproof material used to protect joints or materials from water damage. Typically used around windows and doors, chimneys, between the house and ledger board for decks and porches and where roofs intersect.

Fly Rafters: The end rafters of the gable overhang supported by the lookouts.


Gable: The end, upper, triangular area of a home, beneath the roof.

Gable Porch: A style of roof design for a porch that the end is triangular beneath the roof.

Girder: Beam which supports concentrated loads, such as a girder supporting floor joist or trusses.

Wood Grading: The inspection and marking of wood to determine its acceptability for use.

Green Building: A specific energy efficient agenda to construct a home using materials from renewal resources, energy efficient HVAC systems, Energy Star rated appliances, etc. Consult your dealer to learn more about building GREEN.

Green Logs: Logs that are used within a short period of time from harvest to milling.

Green Wood: Wood fiber saturation moisture content of 28 percent or above is considered green wood.


Handcrafted: A handcrafted log home is typically made of full logs left in their natural state that have been hand peeled and hand scribed.

Hand-peeled: The process of removing the bark and outer layer of a log. Usually done using a drawknife or machined to achieve a hand-peeled look.

Header: The horizontal structural member over an opening – e.g. door or window. A beam placed perpendicular to joists and to which the joists are fastened

Hearth: The fireproof area directly in front of a fireplace. The inner or outer floor of a fireplace usually made of brick, tile, or stone.

Heartwood: The wood in the center of the tree that is typically the higher strength and quality and more resistant to decay.

Hewn: Roughly dressing wood by an axe or adze to create a more rustic appearance

High Altitude Glass Windows: Traditionally High Altitude glass contained a small capillary tube between the layers of glass to equalize the pressure between the glass layers with the outside air pressure. This glass does not contain argon as the glass is vented. However, our primary glass supplier, Pella Windows & Doors, now makes available a high altitude glass containing argon which is acclimated at the factory to match atmospheric pressure at 5500 foot elevation. This process removes the stress on the glass seal when placed in a home at a high altitude. This glass is suitable for placement in homes near 8000 foot elevation. Most window manufacturers recommend high altitude glass for homes over 3500 feet elevation.

Hip Roof: A style of roof where all sides slope downward to the walls –or a roof that rises by inclined planes from all sides

Hybrid: A style of wood frame home that uses construction and material elements from a variety of sources, such as log, timber frame, panelized, post & beam, stucco etc.


I joist: Engineered joist with flanges of 2 x materials and the web made of OSB. Cross-section shape looks like the capital letter I. Can be used in floor and or roof systems

Insulated log wall: A wall system consisting of conventionally framed or structural insulated panel core.

Insulation: The protecting of a structure from heat loss by filling wall, roof and floor voids with materials which retard heat flow. Typical insulation materials are fiberglass, loose fill, spray foam and rigid board materials.


Jamb: The side, head, and sill lining of any window, door, or other opening.

Joist: The structural members that supports the floor and ceiling loads.


Kerf: The width of cut made by a saw blade.

Keyboard: Typically a small dimensional board about 1 1/4”x 1 1/4” that is attached to a window or door buck and placed in a groove about the same size as the keyboard that acts as a spline allowing movement of the logs up and down the keyboard while maintaining a stable and weather tight connection between the buck and log. Keyboards are frequently used where there are differing rates of movement between structural material such as doing a log addition to a stick built or log home. Some hand crafters use key boards as a spline in the butt joints of logs to stabilize and seal the connection.

King Stud: A full length stud located at each end of a header and parallel to the trimmer. The king stud holds the header and trimmer in place.

Kiln Dried Logs or Lumber: Logs or lumber are placed in a kiln chamber or building and subjected to heat and humidity conditions to artificially dry the log to achieve specific moisture content. Alternative to air dried logs or lumber.

Knee Wall: Low wall resulting from a 1 ½ story construction, split level homes, crawl space walls, short walls in attic room construction and others.


Lag Bolt: A large heavy wood screw (typically 1/2” diameter x 10”-12” length) with a course thread and hexagon head used in securing logs courses together. Larger diameters and lengths are also common in log home construction.

Landing: A platform or landing between flights of stairs or at the termination of a flight of s

Lally Column: Support column or spot footings, interior footings for support.

Lintel: Horizontal support member in framing over a door or window opening; also called a “header”.

Load-Bearing Wall: A wall that supports weight located above it.

Lock-Up: Weather tight log home package. Term that includes the log wall system, interior rough framing, window and exterior door package, roof system including the protected sheathing.

Log Grading: Evaluation of logs according to specific standards developed to ensure safe and sound construction. All logs are inspected and graded in accordance with standards set forth by Timber Products Inspection, Inc. (TPI). TPI is recognized and accepted by all three of the National Building Codes and the Department of Housing and Urban Development. The TPI grade-stamp is located on every log between the tongues or at the end of the log so that it is visible by the inspector after the logs are stacked. Logs are graded for structural properties and appearance; and are cut on site (header and log walls).

Log Homes Council: The Log Homes Council is a national organization with membership comprised of manufacturers of log homes. The LHC is part of the Building Systems Councils, a council of the National Association of Home Builders. For more information go to:

 Log Home Package: A log package contains the materials and support services that provide the log wall system, roof system, windows and doors, etc.

Log Profile: The cross-sectional shape of a log. There are a variety of milled profiles such as D-log, Round-round, Square, Swedish Cope, etc.

Log Shell: Describes the basic structure of a log homes outer structure that includes the sub- floor system, log wall system, second-story floor system and roof system.

Log Siding: Milled from dimensional lumber that is given a full log appearance.

Log Staircase: A style of staircase using full logs for the stringers, half logs for the treads and a log railing system.

Log Truss: Is a decorative or structural member using custom fitted logs to create a triangle.

Lookouts: A short wood bracket or cantilever that supports an overhang portion of a roof.


Milled logs: Logs that are milled or cut by a machine to a uniform diameters as well as style.

Moisture Content: The amount of water contained within wood, most commonly as the percentage weight of water relative to the over-dry weight of the wood. Water contained within the wood may be ‘free water’ found between wood cells or ‘bound water’ found within the cell walls. Drying of wood does not result in significant shrinkage until all free water has been removed. The point at which no free water remains and shrinkage begins is known as the fiber saturation point (FSP), which occurs at about 28 percent moisture content.


Newel Post: Vertical anchor post at the top and bottom of a staircase system or other transitions in the railing systems. The top and bottom rails are attached to a newel post.

Non-bearing Wall: A wall which supports its own weight only and does not carry any structural load.


On-center (O/C): The usual measurement for spacing studs, rafters, floor joists, etc. It is the measurement from the center of one member to the center of the next.

O.S.B. (Oriented Strand Board): An APA rated structural panel replacement for plywood which usually outperforms plywood of the same dimensions. OSB can swell when exposed to wet conditions and frequently not shrink back to its original thickness when dry.

Overhangs: The roof extension that is beyond the outside wall of the log home. Typically log homes have roof overhangs 24” or more to protect the log walls from the elements.


Partition Wall: Also considered a non-bearing wall, a partition wall is any wall that does not support any load bearing weight. Its purpose is only to divide space.

Piling: A pier or wood column used to support a home; usually, sunk in the ground.

Pilaster: Typically a vertical structural support along a log wall that is connected using lag bolts in a slip joint. Used to maintain vertical straightness of a log wall or connect interior framing to a log wall.

Pitch: The slope of a roof; rise over run. A pitch of 6 means that the roof projects up 6 inches for every 12 inches of horizontal run.

Plate: A horizontal member which supports other members; dormer plate, sill plate, etc.

Plumb: A member or unit which is exactly vertical. A door should be hung plumb.

Post & Beam: A type of construction where wall support is provided by vertical posts and horizontal beams.

Pre-hung Door: A door frame assembly with the door already mounted with the hinges in jambs and ready to install.

Pre-cut Logs: Logs that have been cut at the manufacture per specifications. Your Footprint Log Home is 100% pre-cut log home package.

Pre-drilled log home package: Logs that have been drilled for lag bolts, thru bolts and electrical chases per specifications. Your Footprint milled Log Home is 100% pre-drilled log home package if lags are to be used.

Preliminary Floor Plans: An initial set of floor plans with elevation drawings.

Preservative: A chemical compound applied as a liquid, which is used to help prevent rot and/or insect damage to wood. Sometimes, but not necessarily a stain.

Pressure Treated Lumber: See ACQ Pressure Treated Lumber.

Prow Roof: A popular style of log home design where at the gable end the roof ridge extends further than the sides creating a point. The length of the prow is typically 4-6’ longer that the sides.

Purlin: A horizontal structural member that provides intermediate support for common rafters in roof construction.


Rafter: A structural member used to support the roof; the roofing is nailed directly to the top of the rafters.

Rake: The sloping edge of a roof on the gable end.

Ridge: The top junction of two sloping surfaces.

Ridge Beam: A structural beam, logs, multiple logs or engineered lumber designed to support the upper ends of the rafters and to carry the roof load to load bearing walls or posts.

Ridge Vent: A roof ridge louver system to promote attic ventilation.

Ridge Post: A load bearing post supporting the ridge beam. Typically round logs or engineered lumber.

Rise & Run: The rise is the vertical height of the roof as measured from the level of the wall top plate to the ridge. The run is the horizontal distance from the outer exterior wall to the point directly below the ridge of the roof.

Roof Truss: A triangular assembly made with 2X4 or other dimension lumber for top and bottom chords and webs. Members are joined with toothed metal connector plates pressed onto both sides of the joints. Trusses are made in a wide variety of “standard” and “custom” configurations for support of roofs. They are custom-computer engineered for all span and load factors for each building. In addition, frequently used S4S trusses and trusses made of logs which may have decorative metal brackets as connecting hardware.

R-Value: A measurement of a material’s resistance to the flow of heat. R-value is a laboratory measurement based on the constant temperatures on both sides of a material. However, it does not reflect the fluctuating conditions that face the insulating materials in actual use, nor does it include the effect of thermal mass on energy efficiency.


Saddle Notch: A type of log corner system where the upper log has a notch cut in the shape of a saddle which rests over the bottom log. Also known as saddle cope or round notch.

Sapwood: Wood that is near the surface of the tree between the bark and heartwood.

S4S: Smooth milling on 4 sides of a piece of dimensional lumber.

Scribing: Shaping of wood member to provide for fitting one of its surfaces to irregular surface of another.

Sealant: The soft, pliable material used to seal the area between individual log courses. This material can expand or contract as conditions dictate and retain its elasticity to bond.

 Sheathing: Plywood or OSB installed over framing to provide a flat surface for siding or roofing and to act as racking resistance of the frame.

Settling: Movement of logs and log walls downward as they dry.

Shed Porch: A style of porch where the roof is pitched on a slope.

Shed Roof: A style of roof that has a single plane that slopes away from the roof ridge or in one direction.

Shim: Wood or metal wedge used to level or plumb.

Seismic: The effect of earth movement on a structure. The higher the seismic code the more stringent the shear wall requirements will be. The additional material and hardware can cause challenges and increased building costs.

Snow Load: Climatic value used for the design of structural members. Check your local building codes for your areas snow load calculation and requirements.

Snow & Ice Shield: A self-adhering water proof membrane used for roofing underlayment to prevent ice damming in cold climates.

STK: Sound Tight Knot. A knot that will not fall out of the board and does not allow air or water to pass by. Also known as Tight Knot.

S.P.F.: (Spruce, Pine & Fir Wood Species) Kiln-dried SPF lumber is used as a structural framing material in all types of residential, commercial, industrial and agricultural building applications.

Stick-built: Conventional construction using studs or dimensional lumber to construct the home.

Soffit: The area below the eaves and overhangs. The underside where the roof overhangs the walls. Usually the underside of an overhanging cornice.

Starter Course: The first row of logs mechanically attached to the sub floor.

Strong Back: A 2×6 nailed on edge to a lookout to provide structural support to an eve.

Stringers: The angled sides of a staircase which support the stair treads.

Stud: Wood dimensional framing lumber typically 2”x4” or 2”x6” used to construct a wall.

Sq. Ft.: “Square Foot”

Sub Fascia: Dimensional lumber attached to the end of a rafter or truss that acts to square the frame and add structural support. The fascia boards are attached to the sub fascia.

Swedish Cope: Method of cutting concave section on upper log to rest on the convex portion of lower log.


Tempered Glass: Glass that has been specialty heat treated and cooled for greater strength and durability. The tempered glass will not shatter or create shards, but will “pelletize” in small pieces. Typically building codes require tempered glass in windows for the bathroom, entry door glass and sidelight glass, etc. Consult your local building department for building codes in your area.

Thermal Mass: The insulating property of a solid log wall, whereby heat is absorbed and slowly released over time. To learn more about the energy efficiency performance of log homes, go to:

Toe-nailing: Drive a nail at an angle through one wood member into another.

Tongue & Groove: Panel or board in which one is cut with projecting tongue to fit into corresponding groove in edge of next member.

Top Plate: Horizontal framing member along the top of a wall to which the vertical studs attach.

T.P.I.: See Log Grading.

Trapezoid Glass: Framed glass window with two parallel and non parallel side’s usually one side is an angle matching the roof pitch..

Treads (stairs): The horizontal boards or logs that act as steps in a stairway.

Thru-Bolt System: A threaded rod with a bolt and washer on both ends. Some manufactures offer one end with a spring to provide constant tension. Typically used through a full log wall or corner to apply constant compression as the logs dry and shrink.

Truss: See Roof Truss

Turn-Key: All construction is overseen by one company as in the case of a General Contractor even though he does not do all of the construction. The advantage to the home owner is that he deals with only one company for the construction of their home.


Valley: An inside intersection created at the joint of two roof planes.

Vapor Barrier: A material that prevents moisture from penetrating the surface. Typically used in covering interior walls and ceilings over fiberglass insulation and to cover exterior of the home before finish covering is installed.


Window Buck: The material, typically dimensional lumber used to framed the rough opening for a window.