Timber Frame Glossary

– A –

adz – An axe-like tool with its blade at a right angle to its handle; used to shape or dress timbers.

anchor beam – A major tying beam, joined to post with shouldered-through tenon, wedged from the opposite side.

anchor bolt – A bolt protruding from the top of the foundation onto which the sill plate is fastened with a nut.

aisle – The side section of a timber framed building, separated from the main section by the upright posts forming the arcade.

arcade – The division in a timber framed building, formed of upright posts between the central space (nave) and aisles.

arris – The point at which two surfaces of a timber meet.

auger – A tool for boring holes in timbers.

– B –

backfilling – Replacing excavated soil around a foundation.

bargeboards – Boards fixed to the purlin at the gable.

bay – The space between two bents or cross frames.

beam – A main horizontal member in a building’s frame.

beetle – A large wooden mallet typically weighing 15 to 20 pounds.

bent – A structural network of timbers or a truss connected by various forms of joinery to create one cross-sectional piece of the frame. A series of bents are constructed and are joined to create a self-supporting “skeleton” which will become the framework of the project.

bird’s mouth – A V-shaped notch that resembles a bird’s open beak, cut into the base of a rafter and received by the plate.

box frame – A form of construction where the roof trusses are supported by posts, tie beams and wall plates.

brace – A diagonal timber strengthening a frame; a piece of wood, positioned obliquely, which stabilizes the angle of two other pieces of wood which are connected together.

bressumer – A horizontal beam over a fireplace opening; a beam supporting an upper wall of timber framing.

bridging beam – A large floor beam supporting the ends of common joists.

– C –

cantilever beam – A projecting timber that supports an overhang.

cambered beam – A transverse beam higher at the center than the ends.

carpenter’s mark – Incised marks, commonly like Roman numerals, made when cutting the frame that aid identification during raising.

carrying sticks – Sticks placed under a timber to provide a handhold for carrying. Typically, two carrying sticks and four people are needed to carry a timber this way.

chamfer – A simple bevel cut, usually 45 degrees, along the edge of a timber for embellishment.

check – Separation of wood fibers following the direction of the rays, caused by the tension of uneven drying.

clasped – Usually in conjunction with light principal rafters. The purlin is clasped between the collar and the inside of the principal rafters.

collar purlin – A horizontal longitudinal beam supporting collar ties.

collar tie – The horizontal timber connecting the principal rafters partway along their lengths; used to reduce sagging or spreading of rafters.

combination square – A tool to lay out 45-degree and 90-degree angles. The stop is adjustable along the blade for use as a depth gauge. come-along – A hand operated ratchet winch, used for pulling joints together, as a safety tie when raising a bent, and for pulling the frame together during the raising

common rafter – A long, narrow piece of wood supported by the ridge, plate, and purlins, to support the roof. These closely and regularly spaced inclined timbers run from the wall plate to apex, supported by purlins and wall plate and supporting the roof covering, independent of the bent system.

cross frame – The frames connecting the wall frames, commonly used to divide the space into rooms.

cross of occupation – A symbol drawn on one side of a reference line on a ground plan indicating on which side of the line the beams will be situated during the operation “aligning the beams to the ground plan”.

crown post – The central vertical post of a roof truss that connects the bent plate to the collar tie or collar purlin.

cruck – Long, curved timbers framed in pairs, joined by tie beams or collars, which rise from ground level to support the roof purlins. This primitive truss formed by two main timbers, usually curved, sets up as an arch or inverted V. Each half of the cruck is called a blade. A pair is often cut from the same tree.

– D –

dead load – Weight of building, including the roof, floors, walls, etc.

depth – The vertical thickness of a beam.

diagonal grain – Grain that is other than parallel to the length of a timber, greatly reduces the strength of a timber.

dovetail – A tenon shaped like a dove’s spread tail to fit into a corresponding mortise.

drawknife – A knife blade with handles on both ends so that the knife can be pulled by both hands toward the user.

drift pin – Used to pin joints temporarily when test assembling a frame.

drop – An ornamental pendant with a tear-shaped termination to the lower ends of the second-story post of a framed overhang. Also known as a pendill.

Dutchman (also, inlay) – A timber ‘patch’ to cover a defect, previous joinery, or other blemish or error. Color and grain matching make them hard to find.

– F –

face – The surfaces of each timber identified to enable the precise description and therefore construction of each joint.

framing chisel – A heavy-duty chisel typically with 1½ to 2-inch-wide blade, designed to be used with a mallet.

– G –

gable roof – A double sloping roof that forms an A-shape.

gable – The triangular upper part of a wall at the end of a ridged roof.

gambrel roof – A double pitched roof with the lower slope steeper than the upper slope.

gauge – A metal ruler with an axis line on its length; used to determine the exact width of the mortise and tenon.

gauging – Determining the best geometric plane for each piece parallel.

gerces – Minor cracks considered flaws on the wood surface; occurs when wood has been dried too quickly, or when wood has not been completely dried and has been over-exposed to the sun.

girder – Major timber that spans between sills.

girt – Major horizontal timber that connects posts.

green wood – Wood freshly cut that is not dried or seasoned.

gunstock post – A post wider at the top than the bottom. The wider portion provides more wood for intersecting joinery.

– H –

half bent – A principal rafter, a half tie beam and a brace connected by various methods of joinery usually perpendicularly to the king post of a full bent.

half dovetail – A dovetail tapered only on one side.

half lap – A joint in which the two timbers are lapped or let-in to each other.

half-timbered frame – An ancient building system in which the space between the timbers is filled with brick, plaster or wattle and daub, so that the timbers are revealed to the exterior and interior of the building.

halving – Removing of half the depth of two timbers in order that they may cross each other. A half lap.

hammer beam – A roof bracket projecting from the top of the wall that supports a roof truss. The design creates a large roof span with relatively short timbers.

hardwood – Wood of certain deciduous trees, such as oak, maple or ash.

hip – The outstanding angle formed by the intersection of two inclined roof surfaces; opposite of a valley.

hip rafter – A beam placed at the meeting point where two roof slopes create a salient angle; supports and connects the two roof slopes.

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 tying the joint.

– I –

interrupted tie beam – A short horizontal timber that joins and strengthens the sling brace to the post.

irregular timber – A timber that is not perfectly true, unplaned or not perfectly square, having irregular surfaces, unparallel faces or irregular in size.

– J –

jabbing – A process which determines, with the aid of a plumb bob and pencil, the placement of joinery on the face of the wood.

jetty – A cantilevered overhang of one story over the story below it.

joinery – The art or craft of connecting timbers using wood working joints.

joint – The connection of two or more timbers.

joist – A small, parallel timber that supports and completes the floor frame.

jowl – The enlarged head of a main post which allows the tie beam, wall plate and post to be jointed together; enlarged head of any post.

– K –

kerfing – A series of cuts with a circular saw set at a desired depth to remove a section of wood; 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.

king post – A central, vertical post extending from the bent plate or girt to the apex or junction of the rafters. It supports the peak of a triangular truss and tie beam, such as the ridge of a roof. This beam is generally square, not rectangular.

knee brace – A small timber, framed diagonally between a post and a beam, placed obliquely in the corner formed by two other pieces of wood to stabilize the two pieces.

– L –

lean-to – A shed section of a building framed into the main frame.

lining – Snapping the assembly line on one or two faces of each beam of a timber frame structure.

– M –

mortise – A notch cut into a piece of wood that receives a tenon. The groove or slot into which the tenon is inserted.

mortise-and-tenon joint – Any joint in which a projection on the end of one timber is inserted into a groove or slot in another timber.

molding – A decorative cut generally seen on the end of a purlin.

– O –

overall length – Total length of timber including length of tenons on either end.

overhang – Projection of a second story beyond the first.

– P –

peg – A small hardwood dowel 1 to 1½ inches in diameter, usually oak or locust, cut in the direction of the fibers and sharpened on one end; used to hold parts of a assembly (tenon and mortise joinery) together.

pied – The base of a tree or post.

pike pole – A long pole pointed with a sharpened spike used for raising frames. These tools were known as early as the 15th Century, when they were called “butters.”

plate – A horizontal timber at the head or foot of a frame, situated at the bottom of the slope of a roof to receive and support the common rafters; major horizontal timbers that support the base of the rafters.

plumb bob – A plumb with a hole in its center containing a metal cross to which a string is attached.

post – A vertical beam used to support a structure; vertical timbers which reach the full height of the frame.

principal rafter – An oblique element of a bent, parallel to the slope of the roof, which supports purlins. The rafters jointed into the ends of the tie beams. A pair of inclined timbers framed into a bent.

purlin – A piece of wood which sits on the principal rafters, and has been positioned horizontally to support common rafters on a roof; horizontal timbers that connect rafter trusses; longitudinal roof timbers carried by roof trusses which give support to the common rafters.

– Q –

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.

– R –

racking – 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 – Erecting the bents and roof trusses, and joining and pegging the other timbers to the frame.

regular timber – Timbers which are perfectly true: planed and perfectly square and straight, having regular surfaces, parallel faces, regular in size, and are constant in dimension.

ridge – A horizontal timber situated at the top of a roof apex where the two roof slopes meet. The ridge generally supports common rafters; also called a ridge pole

rip saw – A saw designed to cut parallel to grain.

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 structural network of timbers that form a rigid structure to support the roof; the section of the cross frame bordered by tie beam and principal rafters.

– S –

scarf – A joint for splicing two timbers end to end.

sheathing – Boards or waterproof material covering the outside wall of a house or on a roof.

shed roof – A roof sloping in one direction.

shim – Thin tapered pieces of material such as a shingle; used for leveling timbers.

shoulder of timber – Point of intersection at the joint of two assembled timbers; refers to timber with tenon.

sill timbers – Horizontal timbers that rest upon the foundation.

SIPs – see structural insulated panels

slick – A chisel with a blade 2½ or more inches wide, pushed by the hands instead of being struck with a mallet.

sling brace – A brace that runs between the post and principal rafter, strengthened by an interrupted tie beam.

soffit – The underside part of a building such as under a roof overhang.

softwood – Wood primarily of a conifer or evergreen, such as pine, spruce or Douglas fir.

span – The shoulder-to-shoulder distance.

structural insulated panels – Two pieces of oriented strand board with a rigid insulation material (EPS; expanded polystyrene) permanently bonded between them; also called stress-skin panels or SIPs.

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

stub tenon – Tenon that stops within the timber it joins.

summer beam – Major timber that spans between girts or plates.

– T –

tenon (or tennon) – A projection cut on a piece of wood and inserted into a mortise; a shaped, protruding end of a timber inserted into a mortise.

through tenon – A tenon that passes through the timber it joins. When extended past the mortise it is wedged from the other side.

tie beam – A horizontal or transverse timber joining wall frames at eaves level, joins the two principal rafters of a bent.

timber – A large squared or dressed piece of wood.

timber frame – A centuries-old method of construction using a variety of joinery, dimensioned timbers and knee braces pegged together to create bents. Bents are assembled to form a self-supporting skeleton of a structure. The transfer of the load of the structure moves through the vertical components.

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 plate – Horizontal timber supported by main posts that forms the top of the wall.

trench – location at which the purlin is joined to the outside of the principal rafter.

trunnel or treenail – A peg, sometimes extra-large.

truss – Assemblage of timbers forming a rigid framework.

– V –

valley – The recessed angle in a roof where two roof surfaces meet and towards which rainwater will flow; the opposite of a hip.

– W –

walking beams – Two parallel beams laid on the ground used to assist moving timbers with a pivoting action.

wedge – A triangular piece of wood fixed on the principal rafters to keep the purlins in place.

wall frame – The vertical frames running between floor and top plate level, connected by cross frames.

wall plate – See top plate.

wind brace – A smaller timber, framed diagonally between a post and a beam.