Roof Joists Vs Rafters

Rafters form the foundation for attachment of the roof boards onto which the final roof covering is fixed.

Roof joists vs rafters.

The rafters support the sheathing and typically run from the roof peak down to the eaves. In traditional timber they are nominally 2 inches thick and typically 8 to 10 inches wide. A ceiling joist is simply a horizontal framing member that runs between walls or rafters to support a ceiling say editors while a rafter tie is a horizontal framing member that runs between rafters to resist the outward thrust of the rafters. A joist is a horizontal structural member used in framing to span an open space often between beams that subsequently transfer loads to vertical members.

Rafters are the building components that run diagonally from the wall plate to the apex of a roof structure. Rafters form the foundation for attachment of the roof boards onto which the final roof covering is fixed. Roof rafters are typically joined where the two slopes converge along the ridge of your roof running all the way down to the eaves. The rafters carry the dead load of the sheathing and roofing material and the live loads above.

Rafters are typically 2 by 4 s 2 by 6 s 2 by 8 s or 2 by 10s. Trusses and rafters have many common parts including the sloping rafter boards and a bottom joists that form the ceiling of the space below. Rafters may also carry the ceiling loads below on cathedral ceilings. However in canada the most common material used in residential framing is wood so that is the material we will discuss here.

In traditional timber they are 2 inches wide and 8 to 10 inches deep. Rafters are the building components that run diagonally from the wall plate to the apex of a roof structure. However since steeply sloped roofs of more than 2 in 12 are raised up too high for the parallel planks to be considered joists they go by a different name and are instead called rafters.