Glossary of Common Oak Frame Terms
A
A-Frame - A roof truss shaped as an 'A' or Δ, usually symmetrical and comprising a pair of angled principal rafters and a single horizontal tie beam across the bottom. May also contain queen posts, struts or collar.
Aisle - A side frame adjoining the central frame (arcade) of an aisled structure.
Arcade - The central frame of an aisled structure.
Arch Brace - A large curved brace arching up from a post to a tie beam, principal rafter or collar.
Arris - The edge of a timber. Arrises are often rounded slightly after working for appearance and to ease handling during construction in a process called 'arrissing'.
B
Banksman - One whose job it is to relay instructions to a crane operator, either visually with hand signals or by radio.
Barge Board - Seasoned board fitted to the gable end of a building or frame to enclose and protect the section of a pitched roof.
Base - The masonry upon which a structural frame is built.
Batten (also Lath) - Strips of wood attached horizontally to a roof, often to carry slates, tiles or shingles.
Bay - The space between bents or trusses in a framed building.
Beading (also Bead, Bar) - Strips of seasoned wood securing a panel or glazed unit in a frame, often within a rebate.
Beam - A horizontal timber within a frame, often load bearing.
Bearers - Short lengths of wood upon which frame timbers are stacked to ease handling and loading, and prevent inundation outdoors. Usually softwood to prevent marking timbers.
Bent - A transverse frame, comprising truss and any lower structure.
Bevel - An angled cut on the face or end of a timber.
Birdsmouth - A 90 degree cut at the bottom of a rafter, typically to fit onto the inner or outer edge of a wall plate.
Bowing - The bending of timber along its length, often in response to drying, milling or load.
Boxed Heart - A timber milled to retain the heart of the wood running centrally throughout its length.
Brace - A timber positioned to provide rigidity against racking by creating a triangle within a frame.
Bressumer (also Bressumer Beam) - A major horizontal timber in the outer wall of a building, often carrying the jettied upper level of a wall frame. A mutation of 'Breast Summer'.
Bridging Beam - A horizontal timber spanning an uninterrupted open space within a building, often carrying a floor.
Bridle Joint - A mortice and tenon joint with open ends, often found at the apex of rafters.
Butterfly Roof - A roof with its middle lower than its eaves, so each pitch slopes downward from eaves to centre.
C
Cantilever - A timber, usually horizontal, supporting weight outward from its own point of support.
Capping - The top layer of masonry on a base or dwarf wall upon which a frame may sit, sometimes bevelled on the upper outer edge to shed water.
Carpenter's Marks - Marks, usually in Roman numerals, to identify the position and orientation of timbers within a structural frame.
Casement - A seasoned wood frame to house opening windows or door.
Catslide - An extension of a first floor roof downward on one side to ground floor eaves level, traditionally on the north side of a building.
Chamfer - An angled cut on the edge of a timber, often decorative.
Chord - A timber forming part of the perimiter of a frame. For example, chords on an a-frame tend to be the principal rafters and tie beam.
Cladding - Sheeting, weatherboarding or similar fixed to the outside of a building to enclose and protect it from the elements.
Cleat - A block of wood fixed to the upper face of a principal rafter to partly support a purlin.
Cleave - To split a piece of wood along the grain, often performed with a froe or axe.
Collar - A timber, often curved, spanning between opposite principal rafters or cruck blades, sometimes as a tying tension member (tie collar) to resist roof spread.
Common Rafter (also Secondary Rafter) - A rafter directly supporting the roof, usually sitting atop purlins, ridge beam and wall plates.
Corbel - A stone protruding from masonry to provide support for a timber.
Counter Batten - Strips of wood attached vertically to a roof, either under or over horizontal battens, often to allow roof membrane ventilation.
Counter Bore - A wider hole cut to allow the head of a screw or bolt to sit below the surface of a timber, often capped with a plug.
Crown Post - A vertical timber carrying a ridge beam.
Cruck (also Cruck Blade) - A large curved timber reaching up and inward from floor level to cross another at a frame's apex, supporting a ridge. Where its base is jointed into a bridging beam or sits atop a corbel, it is known as an Upper Cruck.
Cruck Spur - A horizontal timber between a cruck and adjacent post.
D
Dead Load - The total downward force exerted by the structure and everything attached to it (eg: roof, cladding, fixing and fittings).
Deflection - The amount of curve in a timber, measured at its maximum from a straight line between ends.
Dormer - A window frame protruding from the pitch of a roof.
Dovetail - A joint shaped wider within its housing to prevent being pulled apart.
Down Brace (also Tension Brace) - A brace angling downward from a post to a sole plate, transom or bressummer.
DPC (also DPM) - Damp proof course or membrane to prevent damp rising from underlying masonry.
Dragon Beam - A horizontal timber jointed at an angle to the corner of a structural frame. May be jointed across the corner of a structure to secure a dragon tie, or cantilevered outward to support the corner of a jettied upper floor and wall frame.
Dragon Tie (also Angle Tie) - A horizontal timber jointed at an angle to the corner of a frame to secure the bottom of a hip rafter, much as a tie beam with a principal rafter.
Drip Groove (also Drip Channel) - A small groove cut in the underside of a timber (typically 10mm from the edge) to force water to drip off instead of tracking under.
Dwarf Wall - A short wall, often between 40-80cm in height, on which a frame may sit.
E
Eaves - The bottom of a pitched roof where it meets with a wall, usually overlapping with soffits and fascia carrying a gutter.
Elevation - The side view of a building or frame in an architectural drawing or frame plan.
End Grain - The perpendicular face of a cut timber, often the bottom of a post or end of a sole plate, may more susceptible to the ingress of moisture by capillary action.
F
Face Edge - The cut edge of a timber, usually 90°, from which measurements are taken.
Face Side - The face of a timber from which measurements and other angles are taken.
Fascia - A decorative board or boards, usually seasoned oak, carrying the guttering at the eaves.
FFL - Finished floor level. Often a common reference point in frame and building plans, from which all vertical measurements are taken by project contractors.
Finial - A decorative board or timber, often covering the join of a pair of barge boards at their apex.
Firring - A tapered strip or batten, usually fixed to the top of a level timber to create sufficient slope to shed water off a flat roof.
G
Gable - The end of an A-framed building or structure.
Gambrel - A roof with two pitches on each side, the lower steep and the upper shallow.
Grain - The direction of the fibres in a timber.
Groove - A channel cut into the surface of a timber, often to accommodate a seal.
Girt - A horizontal timber within a wall frame at first (or additional) floor level, often supporting joists.
Green Oak - Unseasoned oak (Quercus spp), typically within a year and a half of felling with a moisture content of 60-80%.
H
Header Joist - A joist spanning between trimmer joists abutting a stair well, carrying the truncated ends of tail joists.
Heartwood - The harder wood towards the centre of a timber, which tends to be more durable than sapwood.
Hip Rafter - A rafter descending the external angle from the apex of a roof to the corner at the eaves where two pitches meet, usually carrying the upper ends of jack rafters.
I
Intermediate Post - A post within a frame which, whilst not a principal load bearing timber, still provides significant support.
Interrupted Tie Beam - A horizontal timber securing the bottom of a principal rafter over a wall plate, which is truncated by another timber such as a sling brace.
J
Jack Rafter - A common rafter jointed into a hip or valley rafter.
Jam - A vertical timber forming a side of a window or doorway casement.
Jetty - The upper part of a building which overhangs a lower part.
Joist - A horizontal timber carrying a floor.
Jowl Post - A post which widens at the top to allow additional jointing, for example a teasel joint into a tie beam.
K
Kerf - The width of a cut made by a saw, usually determined by the set of the saw's teeth.
Knee Brace - A brace between a post and a horizontal timber above to create a rigid triangle.
King Post - A central vertical post in a truss into which the principal rafters are jointed at the apex, with ridge beam jointed atop. The top of the king post acts much like a key stone in an arch, with the bottom of the post lifting the middle of the tie beam, rather than bearing down upon it.
King Strut - Much the same as a king post but without carrying a ridge beam.
L
Lantern - A glazed frame sitting atop a roof, often on an orangery or similar open space.
Lead Time - The time between ordering and delivery - commonly refers to the time taken for oak to be delivered to our workshop.
Ledger - A board or plate fixed to a building to carry the top of a lean-to roof.
Live Load - The total weight of everything on or in a building (occupants, furniture, etc.) including snow load, but excluding anything structural or fixed.
Lintel - A horizontal timber over a window or doorway.
Loggia - An open-sided gallery or corridor with a glazed or covered roof.
Longitudinal - The direction along the length of a building or structure from end to end, for example in line with a roof ridge. The opposite of transverse.
Longitudinal Brace - A brace between a ridge beam and a king post, crown post or similar.
M
Mansard - A four-sided gambrel roof. Each side has two pitches, the lower steep and the upper shallow.
Mitre - The angled cut ends or faces of meeting timbers, often at 45° each to form a 90° join between the two.
Mortice (also Mortise) - The female part of a mortice and tenon joint, typically cut into the face a timber.
Movement - An overall term which encompasses the swelling, shrinking, bowing, warping, etc. of timber.
Mullion - A vertical dividing timber within a window.
Muntin - A vertical dividing timber within a panelled door.
N
Newel Post - A post at the end or corner of a staircase or stair well.
Noggin (also Nogging or Dwang) - A small timber fitted between studs, joists or common rafters to prevent warping or bowing.
O
Open Ridge - A ridge without a ridge beam. Pairs of common rafters are normally jointed at their apex with individual bridle joints.
Orangery - A flat roofed extension or garden room with glazed sides, often topped with a glazed roof lantern.
P
Pad Stone - A stone or small slab set into the ground or base to carry the bottom of a post.
Panel - A solid or glazed wall mounted within, as opposed to outside, an oak frame.
Peg (also Trunnel) - A length of wood, normally cleaved seasoned oak round in section, holding a joint together. Common diameters in green oak framing are: 1" (25mm) and ¾" (19mm), plus ⅝" (16mm) and ½" (13mm) for more specialist joints.
Pergola - An outdoor shelter with open sides and topped with beams or lattice, often covered with climbing plants.
Pier (also Plinth) - A stone protruding up from ground or base level to carry the bottom of a post or suspended sole plate.
Pitch - The angle of slope on a roof, usually measured in degrees. Also used to describe the sloped portion of a roof.
Plumb - Precisely vertical.
Plumb Cut - A single vertical cut, for example at the top of a rafter to sit against a ridge board or the bottom of a rafter to carry a fascia.
Pocket - A hole in masonry to accommodate a timber, such as a purlin or ridge beam.
Podger - A metal pin to hold a joint together temporarily in place of a peg during working or assembly of a frame.
Porch - An enclosed space around or forming a doorway.
Post - A vertical timber, usually structural.
Prick Post - A post jointing into the underside of a bridging beam.
Principal Rafter - A main rafter in an A-frame or roof truss, often carrying purlins.
Projection - The horizontal distance an extension, conservatory, porch or similar extends outward from an existing building.
Purlin - A longitudinal timber spanning the width of a bay between trusses to support the middle of the pitch of a roof. Large roofs may contain several purlins supporting each pitch.
Q
Queen Post - A post rising from a tie beam to the underside of a purlin.
Queen Strut - A short post rising from a tie beam to the underside of a principal rafter, either straight or curved, to assist the bearing of weight.
R
Racking - The tilting of vertical members or faces (posts, trusses, etc.) in a structure which may cause a roof or building to collapse sideways, for example as a consequence of wind shear.
Rail - A horizontal timber at the top or bottom of a window casement, or across the top of a balustrade.
Rebate (also Rabbet) - A groove cut from the edge of a timber, often to house glazing, panelling or sarking within a frame.
Residual Section - The portion of a timber's section remaining at a given point after all joints and peg holes have been worked.
Ridge Beam - A beam spanning the width of a bay between the apex of trusses to support the ridge of a roof.
Ridge Board - A narrow board along the ridge of a roof into which common rafters are nailed or screwed, often to provide rigidity in the absence of a ridge beam.
Roof Spread - The outward spreading force which would be exerted upon the side walls of a building by a ridged roof, if not resisted by a tying member such as a tie beam or tie collar.
S
Sapwood - The softer, more porous living wood forming the outer part of a tree's stem, including the vascular bundles of xylem and phloem, which tends to be less resistant to insect attack and ingress of moisture than heartwood.
Sarking - Boards lining the roof frame to form a ceiling, for example atop common rafters, often tongue and groove.
Scarf Joint - A joint to fix timbers end to end. There is a wide variety of scarf joints, for example: tabled, abutted, bridled, fished, splayed and keyed.
Seat Cut - A single level cut, for example at the bottom of a rafter to sit atop a wall plate.
Section - The area across the width and breadth of a timber.
Shake (also Check) - Longitudinal cracks in timber, usually caused by drying. Whilst often visible in green oak frames as timbers mature, surface shake tends not to result in any loss of structural strength.
Shear - Force exerting stresses upon the material of a structure.
Shoe - A shaped steel plate or shaped bracket, usually stainless steel, securing the base of a post, cruck or similar.
Shoulder - The cut face of a tenon joint which bears against the timber containing the mortice, often subject to considerable compression where a post joints into a plate or a principal rafter into a tie beam.
Sill (also Cill) - A horizontal timber forming the bottom of a window or doorway.
Sling Brace - A large curved timber arching up from a bridging beam or post to a principal rafter or collar and supporting the truncated end of an interrupted tie beam.
Snow Load - The calculated load exerted upon a roof by the maximum anticipated snowfall plus other accumulation. A component of live load.
Socket - A recess in timber to accommodate the section of another timber jointed into it, for example where a purlin is jointed into a principal rafter or a joist into a bridging beam.
Soffit - A board enclosing the underside of a roof's eaves.
Sole Plate (also Bottom Plate) - A horizontal timber at the bottom of a wall frame, often jointed to others to run continuously around the base of a structure.
Sprocket - An extension to the bottom of a common rafter, usually to provide a shallower pitch at the bottom of a roof.
Staddle Stone - A stone supporting an elevated sole plate or post base. Often mushroom shaped so its wider top prevents rodents from ascending.
Stair Well - The open space in a floor frame to accommodate a staircase.
Storm Porch - An open sided shelter over or around a doorway.
Stringer - The angled timber carrying the steps of a staircase.
Strop - A looped strap for lifting a frame or timbers, often with a crane.
Strut - A timber angling upward from the bottom of a king post to the underside of a principal rafter.
Stud - A minor vertical timber within a frame, often to carry panelling or cladding.
Subsill - A horizontal timber below the sill or threshold of a doorway, often jointed below finished floor level (FFL) beneath the base of adjacent doorway posts.
Summer Beam - A horizontal load bearing timber spanning a clear space, usually carrying joists.
T
Tag Line - A length of thin rope secured to a frame or timber to stabilise and direct it during craning.
Tail Joist - A truncated joist which joints into a header joist at a stair well.
Teasel (also Teazel or Teaze) - A joint securing a wall post, typically a jowl post, to a tie beam as part of a tying joint.
Tenon - The male part of a mortice and tenon joint, typically at the ends of a timber.
Threshold - A horizontal timber forming the bottom of a doorway.
Tie Beam - A horizontal timber spanning the bottom of an A-frame to resist spreading forces exerted by the weight of the roof and tie the walls.
Tie Collar - A timber, often curved, spanning between opposite principal rafters as a tying tension member to resist roof spread.
Tilting Fillet - An angled batten fixed to the upper faces of common rafters to provide a more level upper surface at the eaves.
Topping Out - An oak framing tradition to celebrate the fitting of the final timber in a frame, often featuring a sprig of yew (Taxus baccata) at the apex of the roof.
Transom - A horizontal timber within a frame.
Transverse - Across the width of a building or structure, typically from eaves to eaves in line with a truss or bent. The opposite of longitudinal.
Trestle (also Saw Horse) - A frame often comprising linked triangles, usually (in the workshop) to support timbers during working.
Trimmer Joist - A joist abutting a stair well, carrying one or more header joists.
Trimmer Rafter - A transom in a roof to supporting one end of a common rafter. A skylight will usually be framed by a pair of trimmers.
Truss - The supporting frame of a roof, typically an A-frame.
Tying Joint - A joint tying together two or more planes of a building, for example a wall frame to a bent or truss.
U
Upper King Strut - Much the same as a king post or king strut but where the bottom is jointed into a collar.
Upstand - The vertical distance between the top of a finished roof (eg: of an extension) and the flashing chased into the existing building.
V
Valley Rafter - A rafter descending the internal angle from the apex of a roof or dormer to its lower corner where two pitches meet, usually carrying the lower ends of jack rafters.
W
Wall Plate (also Top Plate) - A horizontal timber at the top of a wall frame or sitting atop masonry to carry a roof frame.
Warping - The twisting of timber along its length, typically in response to drying or milling, especially in the presence of spiral grain.
Wind Brace - A brace between a purlin and principal rafter to resist roof racking.
Wind Load - The horizontal force exerted by wind upon a structure.