Roof Rafter Terminology

Roof framing involves a lexicon all its own.

Roof rafter terminology.

When repairing or replacing a roof it pays to be familiar with these terms. A principal common rafter roof or double roof. Length in plan of the rafter from a structural beam or wall to another structural beam or wall. Rafter a vertical sloping timber used to form the shape of the roof the side of a truss.

A term used to describe a pitched roof the ends of which are also sloped. Principal rafter major rafter rarely a chief rafter. Tlor total length of rafter this is the total length from center of ridge to the facial cut. Definition of valley rafter or cripple jack rafter.

In the sketch above the valley rafter is drawn in yellow. Ridge the horizontal line at the top of a pitched roof applies whether there is a sloping roof on both sides a duo ridge or if there is just one a mono ridge. Ll line length also called lor. Lor length of rafter this is the mathematical length from the center of the ridge to the outside of the wall.

A bearing timber forming part of a suspended timber floor to which the floor boards are nailed to the top and a ceiling may be attached beneath or. In most cases in this manual tails are added later. Here is a closer look at common roofing terms. Being smaller than a principal rafter.

Auxiliary cushon compound. Rafters are inclined members spaced from 16 to 48 inches apart. Rafters on opposite sides of the ridge should be installed directly opposite each other in pairs although if you see a few that don t align it s really not a defect. Common rafter terminology.

Application of calculations rafter lengths calculated mathematically. Eave span length the horizontal length i e. The tops of the. Rafter the members making up the main body of the framework of all roofs are called rafters.

Interior span length the horizontal length i e. They vary in size depending on their length and spacing. Roof live load see snow or non snow. They do for the roof what the joists do for the floor and what the studs do for the wall.

Rafters which rest on the outside walls at the bottom and connect to the ridge at the top are called common rafters highlighted here in yellow. Includes illustrations that show roofs have hip rafters ridge boards jack rafters and more. Definitions of rafter span run roof span slope collar ties. Roof dead load the approximate weight of roofing materials.

Length in plan of the overhang portion of the rafter. These are short spars that run from a hip to the eves or from a ridge to a valley. Bct 122 roof framing 1 rafter terminology calculations. Usually land directly on a tie beam.