Glossary of Terms

To help our customers better understand the terminology used in the timber framing process, we have included a diagram and a glossary of terms. Right-click on a term in the listings below the diagram to view its definition.
- Bent
The framed structural unit of a timber frame that dictates its height, width, and profile. Bents are assembled horizontally on the building foundation or deck and raised vertically into position where they are joined to one another by connecting timbers. The number of bents used to construct a frame dictates the length of the building. For example, if a frame were built of 6 bents, each 12' apart, the building would be 60' long.
- Bent Tie
A bent timber that connects two posts together at the second floor level. Floor joists connect bent ties from adjacent bents together.
- Common Rafter Roof System
A roof structure consisting of evenly spaced roof timbers that run vertically from the ridge of the house to the top of the second floor wall. These rafters are normally smaller than principal roof rafters. Typically, common rafters are spaced 4' on center.
- Connecting Timber
Any timber connecting bents together such as joists, purlins, girts, nailers and ridge beams.
- Dovetail
A tenon that is shaped like a bird's spread tail feathers that fits into a corresponding dovetailed shaped mortise. A dovetail joint, typically used on the ends of joists and purlins, helps keep adjoining bents from spreading apart.
- Expanded Polystyrene Foam (EPS)
Similar to the white foam that coffee cups are made of, this material serves as an insulating core option for stresskin panels. Polystyrene foam is versatile since it can be manufactured in a variety of thicknesses, which determines the panel's R-value or resistance to heat flow.
- Girt
Framing timber, often 6" x 8" in dimension that connects bents together at the post. Girts typically have knee braces joined into them from the post.
- Hardwood
A deciduous tree species that loses its leaves each year. Hardwood species have a denser and stronger wood fiber than softwood species. Common hardwood species in Vermont are American beech, yellow birch and sugar maple.
- Hybrid Construction
The mixing of different construction techniques. As it relates to timber framing, "hybrid" construction is the mixing of conventional "stick built" construction and SIP construction with timber framing.
- Joinery
The craft of connecting timbers together using wooden joints.
- Joint
The connection between two timbers.
- Joist
Medium sized floor timber, often 6" x 8" in dimension that connects bents together at the bent tie.
- Knee Brace
A small timber that is joined diagonally between a post and a beam to add lateral support to a frame. Knee braces also add to the aesthetics of a timber frame. Our standard knee braces are curved in profile
- Layout
The process of transcribing joinery information from frame plans to the face of the timber using a pencil and framing square.
- Mortise
An elongated slot cut into a timber that a tenon is inserted into. The resulting joint is then secured with a hardwood peg.
- Off-gas
In the construction field, off-gassing is the emission of unhealthy fumes or toxins, such as volatile organic compounds or formaldehyde, from a building material. An advantage of using SIPs is that the materials used in their construction do not off-gas.
- Oriented Strand Board (OSB)
A structural building sheathing used in the production of SIPs. OSB is formed by compressing a mixture of thin wood strands with resin binders. OSB has greater structural properties than plywood because it is manufactured with cross directional layers of wood strands that tie the entire board together, unlike plywood that is a laminate of 6-7 thin layers of wood.
- Planed Surface
A smooth timber surface achieved by passing a hand held planer over the timber surface or by passing the entire timber through a 4-sided planer. A planed frame appears more formal or finished than a rough-sawn frame.
- Post
A vertical member in a timber frame.
- Principal Rafter
A heavy bent timber that runs from the ridge of the house down to the wall.
- Principal Rafter/Purlin Roof System
A roof system where principal rafters are connected by horizontal purlins to create the plane of the roof. Purlins are typically spaced 4' on center.
- Purlin
Small roof timber that connects principal rafters. Purlins have a dovetail joint on each end to secure them into the principal rafters.
- Raising
Standing the timber frame bents onto a deck or foundation and connecting them together to form the final structure. In the past, raising a timber frame was accomplished by using a large group of people to push the bents into standing positions. Today, a timber frame is more commonly raised with the use of a crane and a small crew of people.
- Rough Sawn
Timber that is milled with either a band saw or circular saw and retains a surface that is rough to the touch. Frames that are made from rough sawn timber typically have a more rustic look.
- R-Value
R-value is a rating used to measure an insulation's ability to resist heat flow. The higher the R-value, the more effective an insulator it is. When using SIPs, a thicker panel will have a higher R-value.
- Scarf Joint
A structural joint where two timbers are joined end to end to create a longer timber.
- Shouldered/Housed
When a timber is shouldered or housed at a joint, the entire end of one timber is recessed into the other. Used together with a mortise and tenon, this system minimizes twisting of the frame as it dries and adds considerably to the strength of the frame. Depending on its location in our structures, all our joints are shouldered 1/2" or 3/4" in depth.
- Softwood
Typically a conifer or evergreen tree. Softwood species have a less dense and weaker wood fiber than hardwood species. Common softwood species in Vermont are Eastern hemlock, Eastern white pine and red spruce.
- Spline
A milled piece of hardwood that is slotted through a post and connects adjacent girts together. Both girts are pegged into a common spline and create a connection through the post. The splines used by Alces Post & Beam are 1-1/2" wide x 4" high.
- Stick Framed, Stud Framed or Stick Construction
Traditional residential building technique where walls and roofs are framed on-site with individual wood studs that are nailed together. This type of construction is more labor intensive than timber framing and requires considerably more time to frame and enclose a structure.
- Structural Insulated Panel (SIP)
A pre-manufactured laminate of oriented strand board (OSB) or plywood attached to both sides of a foam core. SIPs are commonly applied to the exterior of timber framed structures to insulate the walls and roof of the house. They are attached using galvanized spikes or screws.
- SIP Spline
A strip of plywood or OSB that is inserted at the panel joint on both the interior and exterior surfaces. Screws applied into this spline through the panel on both sides of the panel joint secure the panels to one another.
- Tenon
A rectangular projection cut on the end of one timber that fits into the mortise of another timber and is secured with a hardwood peg.
- Thermal Bridging
Thermal bridging occurs when there is an interruption of insulation in an exterior house wall by other materials such as stick framing. Since these thermal bridges (wall studs), have a lower resistance to heat flow (R-Value) than the insulation between them, heat is lost at these locations. In common stick construction, up to 10% of the exterior walls can be un-insulated thermal bridges.
- Truss
A triangular timber structure typically built with two rafters and a collar tie that spans between two walls and supports a roof.
- Valley Timber
The timber where two separate roof structures come together at a 90 degree angle.
- Whole R-Value
R-value of the entire wall including all the components of its construction. In traditional stick framing the whole R-value is actually less than the R-value of the insulation between the studs because heat is lost through the studs because they are poor insulators. (See Thermal Bridging)
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