Flat Roof Rafter Vs Joists

Rafters are the building components that run diagonally from the wall plate to the apex of a roof structure.

Flat roof rafter vs joists. Conventional framing the first thing to understand is how a roof framed with wood i joists differs structurally from a traditional stick framed roof. Both of these are for light roof loads. They are nailed securely to exterior wall plates and to each other. Ceiling joists can be on both low sloped roofs and high sloped roofs and help to prevent racking and spreading of your rafters or walls which could lead to sagging.

The major functional difference between the two is that trusses are built mostly with 2x4s in place of the wider dimensional boards. Trusses and rafters have many common parts including the sloping rafter boards and a bottom joists that form the ceiling of the space below. As mentioned above a 2 4 spf shed roof rafter can span 11. 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. The rafters in a flat roof serve as ceiling joists for the space below. They are important load bearing structural elements. Corbett grace their parents and even their kids are learning a lot about the many ways a few right many wrong to build a high performance home.

Rafters form the foundation for attachment of the roof boards onto which the final roof covering is fixed. An syp rafter can span 11. In a typical roof framed with dimension lumber the rafters rest on the exterior wall top plate at the lower end and bear against a ridge board at the top. Similarly ceiling joists are the planks of wood that create the flat surface of your attic floor or top story ceiling.