In our previous post, we began our exhaustive timber frame home glossary. Today we'll continue to cover key timber frame terms that are used during the construction of a timber frame building. Enjoy!
Timber Frame Terms H-Z
Half Dovetail: A dovetail tapered only on one side.
Half Lap: A joint in which two timbers are lapped or let in to each other.
Half-Timbered Frame: An building system in which the space between timbers is filled with brick, plaster, or wattle and daub. The resulting look reveals the timbers to both the exterior and interior of the building.
Halving: The removal of half the depth of two timbers in order that they may cross each other.
Hammer Beam: A roof bracket projecting from the top of the wall that supports a roof truss. The design creates a large span with relatively short timbers.
Hand-Peeled: The process of removing the bark and outer layer (cambium) of a log. Hand peeling is usually done using a drawknife, although some companies use machines to achieve a hand-peeled look.
Header: Built-up horizontal member of a home's frame that tops a window or doorway.
Heartwood: The inner layers of wood which in the growing tree have ceased to contain living cells, as opposed to the sapwood, which contains growing cells. Heartwood is generally darker in color than sapwood.
Herringbone bracing: A decorative, supporting style of frame, usually at 45° to the upright and horizontal directions of the frame.
Hewn: Cut with an axe or an adze. Also called hand hewn.
Hip: The angled ridge formed by two adjoining planes.
Hold-Down Rod: A metal rod that provides extra anchorage of the roof system to the logs. These are desirable in high wind areas.
Hook Pin: A fastener used to pin joints temporarily when test-assembling a frame. Also known as a drift pin.
Housed Mortise: A recessed mortise in which bearing is provided for the entire width of the tenoned member.
Housing: The shallow mortise or cavity for receiving the major part of a timber end. Usually coupled with a smaller deep mortise to receive a tenon for typing the joint.
Jetty: An upper floor that depends on a cantilever system in which a horizontal beam (the jetty bressummer) projects forward beyond the floor and on which the wall above rests.
Joinery: The art or craft of connecting timbers using woodworking joints.
Joint: The connection of two or more timbers.
Joists: Small, parallel timbers that complete the floor frame.
Kerf: The groove formed in wood while being sawn or the thickness of the wood removed as sawdust.
Kerfing: Used to describe either a series of cuts with a circular saw set at a desired depth to remove a section of wood or the hand-sawing along the shoulder of an assembled joint to improve the fit of the joint.
Keyway: A joint between the footing and foundation wall.
Kiln-Dried Lumber: Lumber that has been seasoned in a dry kiln, often to a lower moisture content below that of air seasoned lumber.
King Post: A central, vertical post extending from the bent plate or girt to the junction of the rafters.
Knee Brace: A small timber that is framed diagonally between a post and a beam.
Layout: The drawing of a joint on a timber before it is cut.
Live Load: Weight due to occupancy of building (people, furnishings, etc.).
Load: Term used to describe weight put on a frame or framing member.
Maximum Allowable Fiber Stress in Bending: Safe design standard for fiber stress.
Maximum Allowable Horizontal Shear Stress: Safe design standard for shear stress.
Modulus of Elasticity: A measure of rigidity of a material. The ratio of stress (force per area) to strain (deformation of wood).
Moment: The product of force times the distance from which it acts, which causes a beam to bend.
Moment of Inertia: A property that reflects the strength of a timber dependent upon the size and shape of its cross section.
Mortise-and-Tenon Joint: A fastening method frequently used in timber framing. One piece of wood has a slot (mortise), while the other component has a projecting member that fits into the slot (tenon). The mortise & tenon is often secured in place by the addition of hardwood dowels or pegs. Types include:
- Open mortise. A mortise which has only three sides.
- Stub mortise. A shallow mortise whose depth depends on the size of the timber. Also a mortise that does not go through the workpiece.
- Through mortise. A mortise which passes entirely through a piece.
- Wedged half-dovetail. A mortise where the back is wider, or taller, than the front, or opening. The space for the wedge initially allows room for the tenon to be inserted, the presence of the wedge, after the tenon has been engaged, prevents its withdrawal.
- Through wedged half-dovetail. A wedged half-dovetail mortise which passes entirely through the piece.
Noggin Pieces: The horizontal timbers forming the top and bottom of the frames of infill-panels.
Nominal Size: Undressed dimension of lumber.
Overall Length: Total length of timber including length of tenons on either end.
Overhang: Projection of second story beyond the first.
Partial-Width Notch: A notch on the tension or compression face of a bending member that does not extend across full width of the face.
Peg: A wooden dowel one to one and one-half inches in diameter, usually of oak or locust.
Pike Pole: A long pole pointed with a sharpened spike used for raising frames. These tools were known as early as the fifteenth century as butters.
Pin: Small peg.
Plates: Major horizontal timbers that support the base of the rafters.
Post: Posts are any vertical timber.
Post-and-Beam: Another term used to describe timber frame construction.
Principal Rafters: A pair of inclined timbers that are framed into a bent.
Purlin: Beams that run perpendicular to the rafters that support them, used to connect the principal rafters of trusses together. Purlins support the roof deck.
Queen Post: A pair of vertical posts of a roof truss standing on the bent plate or girt and supporting the rafters or collar tie.
Rack: The action of straining or winching a frame to bring it into square or plumb.
Rafter Feet: The lower ends of the rafters that are framed into the plate.
Rafter Peak: The point where the tops of the rafters meet.
Raising the Frame: Term used to describe the erecting the bents and roof trusses then joining and pegging the other timbers to the frame.
Reclaimed Wood: Wood that was salvaged intact from old barns, mills, and factories that were built with timber-frame construction. It is salvaged then recycled and reused to build a new structure.
Relish: The material between a peg or wedge hole and the end of a tenon or spline.
Ridge pole/ Ridge Beam : A horizontal timber at the peak of the roof to which the rafters are attached.
Roof Pitch: Inches of rise per foot of run. For example, a 45-degree roof has twelve inches of rise for each foot of run and is therefore called a twelve-pitch roof.
Roof Truss: A structure to support the roof.
Saddle Notch Corner: A saddle notch is an overlapping, interlocking type of log corner. A saddle notched corner ensures a tight fit and superior structural quality.
Scarf: A joint for splicing two timbers, end to end.
Seasoned Wood: Dried wood.
Shakes: Separation of wood fibers that follow the curvature of the growth rings. Normally occurs during growth of the tree.
Shear Failure: Failure from shearing along the fibers of a timber.
Shearing: A force causing slippage between layers.
Sheathing: The covering of boards or the waterproof material on the outside wall of a house or on a roof.
Shim: Thin tapered pieces of material such as a shingle. Used for leveling sill timbers.
Shoulder of Timber: Point of intersection at the joint of two assembled timbers. Refers to timber with tenon.
Shoulder-To-Shoulder Length: Length of timber between the shoulders of the two end joints. (The overall length minus length of end tenons.)
Sill Timbers: Horizontal timbers that rest upon the foundation.
Sloping Timbers: Includes trusses, braces, and herringbone bracing.
Soffit: The underside part of a building such as under a roof overhang.
Spline: A lumber or engineered wood element placed in slot cuts, grooves, dados, etc. to strengthen joints between components. Also known as a free tenon.
Squaring Off: The process of drawing and cutting off one end of a timber so that the cut gives a plane surface perpendicular to the timber's length.
Stand-Alone Timber Frame: A timber fame structure designed to resist loads without the use of shear walls or supplementary structural systems.
Stub tenon: A short tenon whose depth depends on the size of the timber. Also used to describe a tenon that is shorter than the width of the mortised piece so the tenon does not show.
Summer Beam: Major timber that spans between grits or plates.
Teasel tenon: A term used for the tenon on top of a jowled or gunstock post, which is typically received by the mortise in the underside of a tie beam.
Template: A full-size pattern of thin material for laying out and checking joints.
Temporary Bracing: Method of temporarily adding rigidity to a frame during the raising.
Tenon: The projecting end of a timber that is inserted into a mortise.
Tension: A force causing the tendency of extension. In timber framing, captured tension adds rigidity and strength.
Through Tenon: A tenon that passes through the timber it joins. It may extend past the mortise and be wedged from the opposite side.
Tongue and Fork: A type of joint in which one timber has the shape of a two-prong fork and the other a central tongue that fits between the prongs.
Top tenon: The tenon which occurs on top of a post.
Transit: A telescope set on a tripod used for leveling foundation or sill timbers.
Trunnel (Treenail): Term used to describe a peg, sometimes referred to as an extra-large peg.
Truss: The assemblage of timbers forming a rigid framework.
Tusk tenon: A type of mortise and tenon joint that uses a wedge-shaped key to hold the joint together.
Vertical Timbers: Framing that includes posts (main supports at corners and other major uprights) and studs (subsidiary upright limbs in framed walls).
Walking Beams: Two parallel beams laid on the ground used to assist moving timbers with a pivoting action.
Wall-Plates: Located at the top of timber-framed walls, they support the trusses and joists of the roof.
Wedge: A tapered wood element with rectangular cross section used to secure through-tenons, through-splines and scarf joint.
Are there any terms we mentioned in this post that you would like a definition for? Are there any timber-frame terms that you heard of and aren't sure what they mean? Let us know in the comments!
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