Roof Joists Vs Rafters

They are secured at the bottom by ceiling joists.

Roof joists vs rafters.

Rafters form the foundation for attachment of the roof boards onto which the final roof covering is fixed. Roof pitch or slope. 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. This structural support comes in the form of roofing joists ceiling joists rafters or trusses and can be made from a variety of materials including wood metal reinforced concrete etc.

Premade size 4 12 24 ft 50 ft or type scissor attic hip mono and more. The shape and size of a roof depends on the span and the floor. 4 12 roof pitch means 4 inches of rise in 12 inches of horizontal run in short the steeper the roof the more it will cost unless the roof pitch needs to be raised a little to incorporate some attic storage. The major functional difference between the two is that trusses are built mostly with 2x4s in place of the wider dimensional boards.

A gable roof consists of two upward sloping sides that slope at the same angle and from the end look like a symmetrical triangle. But that is another topic. Rafter spans can be extended slightly beyond what the rafter tables suggest when there is a cantelever extending beyond the supporting wall. Use this table to determine the maximum lengths of ceiling joists based on species of lumber joist spacing and joist size.

Gable roofs without ceiling joists provide a much higher and triangular shaped ceiling inside the home. Stick framing is flexible and may. Homeadvisor s roof truss cost calculator gives average prices for trusses by material steel vs. Collar ties placed horizontally halfway down the rafters hold the rafters and roof planes together.

However in canada the most common material used in residential framing is wood so that is the material we will discuss here. 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. Trusses and rafters have many common parts including the sloping rafter boards and a bottom joists that form the ceiling of the space below. While rafters are less and less frequently used today due to the higher cost of rafters vs trusses they do have certain advantages.

In traditional timber they are nominally 2 inches thick and typically 8 to 10 inches wide.