Ceiling Joist Vs Roof Rafter

As nouns the difference between joist and rafter is that joist is a piece of timber laid horizontally or nearly so to which the planks of the floor or the laths or furring strips of a ceiling are nailed while rafter is one of a series of sloped beams that extend from the ridge or hip to the downslope perimeter or eave designed to support the roof deck and its associated loads or rafter.

Ceiling joist vs roof rafter.

They are important load bearing structural elements that hold up both the weight of the ceiling materials for the floor below as well as the weight of any objects or people that may be housed within an attic space. They are nominally 2 inches thick actual width usually 1 1 2 inches and come in a variety of widths from 8 to 12 inches. Their functions are similar to rafters. Called according to its position or use binding joist bridging joist ceiling joist trimming joist etc.

In this case the rafter as a whole is actually stronger than it would have been because the splice is more than adequate and the plywood adds to the strength. In this case the framer just needed a longer rafter. Rafter boards are fastened to the ridge board at the peak and the top plate where they join the wall. Joists are the parallel horizontal beams that run across an open space joining opposite walls in a building to support both the ceiling below and the floor above.

Joists are traditionally made from timber. To make into rafters as timber. The boards creating the slope of the roof are wider than lumber used to build trusses 2x8s 2x10s and 2x12s are most common in rafters vs. Roof joists are found on low slope roofs slope of 2 in 12 or less.

Pictured at left is a 2x6 rafter spliced together using 3 4 plywood. Roof joists may span continuously from one side of the house to another or may be supported on an interior bearing wall. Commonly one of the timbers of a roof which are put on sloping according to the inclination of the roof. Nonparallel ceiling joist designs require additional support construction in the ceiling.

According to the international residential code irc from 2000 one of three methods may be used to maintain a continuous tie support strength across the rafters supporting the roof weight and outward pressure. Where ceiling joists are used to provide resistance to rafter thrust lapped joists shall be nailed together in accordance with table r802 5 1 9 in the irc. Ceiling joists are horizontal members used with rafters and roof joists. They may carry ceiling loads.