Flat Roof Rafter Vs Joists

Similarly ceiling joists are the planks of wood that create the flat surface of your attic floor or top story ceiling.

Flat roof rafter vs joists.

The size of rafters for a flat roof depends on the horizontal span of the building the type and grade of timber used and the load on the roof. The major functional difference between the two is that trusses are built mostly with 2x4s in place of the wider dimensional boards. 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. The rafters in a flat roof serve as ceiling joists for the space below.

If you live in an area that requires a shed roof rafter to support a heavy load then an spf rafter can only span 7. 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. In traditional timber they are nominally 2 inches thick and typically 8 to 10 inches wide. Rafters are the building components that run diagonally from the wall plate to the apex of a roof structure.

Both of these are for light roof loads. They are nailed securely to exterior wall plates and to each other. Trusses and rafters have many common parts including the sloping rafter boards and a bottom joists that form the ceiling of the space below. An syp rafter can span 11.

Rafters form the foundation for attachment of the roof boards onto which the final roof covering is fixed. Conventional framing the first thing to understand is how a roof framed with wood i joists differs structurally from a traditional stick framed roof. 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 main difference between joist and rafter is that the joist is a horizontal structural element transferring load from flooring to beams typically running perpendicular to beams and rafter is a structural members in architecture.