Roof Framing

 

Anti ponding strip

In roofing, tiles and slating. A flat strip of metal flashing material fixed to the top o the fascia and to the rafters to stop the sarking sagging so that no water can pond inside the fascia.

Ashlar piece

Inside roof spaces, lofts and garrets, the short vertical pieces fixed between the floor and the rafters to form short walls. (Not to be confused with ashlar masonry).

Ashlaring

The short side wall frames in lofts, attics, garrets etc.

Birdsmouth

A timber joint,a notch cut out of an angled piece to let it sit on a cross member. Typically in a rafter at the wall plate or at a underpurlin.

C or cee purlins.

Cold rolled sections in the form of a letter “C”. Used not only for roofs but for wall girts and they are used by shed manufactures to form columns, ties and braces. They are also used for floor joists.

Ceiling battens

Supported by and running at right angles to the ceiling-joists the battens typically timber or roll formed metal support the actual ceiling lining material.

Collar tie

In timber roofs a member which spans two opposite rafters, usually at mid span between the wall plate and the ridge to stop the rafters spreading under load.

Common rafter

A roofing timber that defines the slope of a roof. It is set at right angles to the wall plate and rises to the ridge board.

Cripple rafter, Creeper rafter

A short rafter connecting a hip rafter and a valley rafter.

Fascia purlin

Usually in steel shed roofs, a rolled formed comnination of a fascia and a purlin. Can be ordred to suit varying roof pitches.

Fascia stiffener

In an overhanging eaves, a horizontal timber behind the fascia at the hip corners to support the last jack rafters.

Fly brace

A brace from the bottom flange of a rafter to a roof purlin that restrains the rafter laterally.

Hanging beam

A beam that is on top of the members that it is supporting. Typically used in ceilings where a conventional beam would look unsightly or would reduce limited head height.

Hip rafter

An inclined board immediately under the junction of two roof surfaces, the hip. To which are fixed the jack rafters. It runs from the corner of the wall plates up to the ridge.

Jack joists

Short joists at hip ends of hip roofs, running at right angles to the main ceiling-joists

Jack rafter

A rafter that follows the same line as the common rafters, but it meets a hip instead of the ridge board. As a result it is shorter than the common rafters and has an inclined side or cheek cut where it meets the hip rafter.

Metal ceiling battens

Made out of roll formed metal. similar but smaller in profile the roof-battens. Tek screwed to the ceiling joists, more often used in conjunction with gang nail truss construction.

Metal Roof battens

Made out of roll formed metal. In a type of “top hat” section. Tek screwed to the rafters.

Pole Plate

A horizontal member, steel or timber, fixed to the face of a wall to which roof framing is fixed. Typically rafters in a lean to type of roof.

purlin

1.) A horizontal roof member, steel or timber, sitting on the principal rafter of a truss or propped off a wall to support the rafters. AKA Under purlin.
2.) A horizontal roof member sitting on the rafters or on a truss or steel member that the roofing material is directly fixed to. AKA over purlin.

Purlin bolts

Nut and bolt sets specifically designed for fixing cold rolled steel purlins. The bolt and nut heads have the washer with a serrated gripping surface formed integrally.

Purlin bridging

Lightweight roll formed metal channel sections with proprietary end fittings used to stiffen Cee and Zed purlins

Purlin cleat

1.) Steel, a MS plate or angle punched to a set pattern of holes or slots to suit a particular size of steel purlins. Either welded or bolted to the support member.
2.) Timber, a short piece of timber fixed to a support member to hold timber purlins in position.

RHS purlins

Rectangular Hollow Section. Often used as purlins on roof to decks and verandahs, where the structure is exposed to view. Usually the wall thickness used is 2.0mm or 2.5mm. Should always have welded end caps to seal the inside from corrosion.

Ridge board

A horizontal board immediately under the ridge of the roof to which the tops of the rafters are fixed.

Roof battens

Horizontal members fixed to the top of the rafters the battens vary in size and spacing depending on the roof material that they carry. In the larger sizes sometimes called purlins.

Roof framing

The total of the structural roof members which when connected form the support for the roof coverings

Scotch valley, Blind valley, California valley

A method of constructing a variation to a rectangular plan without the use of valley rafters. Far stronger than a traditional framed valley but requires a beam across the walls.

Sprocket-piece

1.) A piece at the foot of a rafter to incline last section of the roof towards the horizontal, to make sprocked eaves.
2.) An outrigger piece attached to the end rafters at the verge of a gable roof to create a gable overhang.

Steel purlin

A horizontal roof member to which roofing is fixed. Mostly cold rolled galvanized steel but can be any steel section thin enough to be easily screwed to.

Tile battens

In roofing they are the horizontal strips of timber nailed across the rafters to fix cement and clay tiles to.

Timber ceiling battens

Made out of timber. Fixed to the ceiling joists in the with serrated grip nails (mostly by by nail guns).

Timber purlin

A horizontal timber or lumber roof member that supports the common rafters, or horizontal roof member to which roofing is fixed, either on the rafters or on trusses etc.

Timber Roof-battens

Made out of timber. Fixed to the rafters in the smaller sizes for slates and tiles with serrated grip nails (mostly by by nail guns), and in the larger sizes by various plate connectors or straps.

Valley jack rafter

A short rafter connecting a ridge board and a valley rafter.

Valley rafter

The main support timber directly under the valley intersection of two roof surfaces. It corresponds to the hip rafter in terms of the same slope and roofing angles. It supports the valley jack rafters and any valley creepers.

Wall Plate

1.) A horizontal member, usually timber bolted or otherwise fixed to the top of a wall to which the roof framing is fixed.
2.) A horizontal member, such as a steel plate fixed to a masonry or concrete wall to carry the end of a beam or to attach a beam to other members.
3.) A horizontal member, either at the top or bottom of a wall frame. Known as top plates or bottom plates.
4.) A board fixed to a vertical surface of a wall to which shoring or props are fixed. Note! when used for the purpose of fixing rafters against a wall then it is known as a Pole Plate.

Wind brace

A structural member that stiffens a structure against the forces of the wind. It can be timber or metal, strut (in compression) or a tie (in tension).

Z or zed purlins

Cold rolled sections in the form of a letter “Z”. Used mainly in large roofs and as wall girts. Zeds have the ability to overlap at the joints giving them a great strength advantage over the Cee purlins. Also can be used as floor joists.