Ceiling Joist Vs Roof Rafter

Ceiling joists are horizontal members used with rafters and roof joists.

Ceiling joist vs roof rafter.

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. 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. 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.

For example if a house has a 4 12 slope the rafters are on 16 inch centers the snow load is 30 psf and the roof span is 28 feet you need eight 16d common nails or 40d box nails at each rafter heel joint connection. In finished space insulation is placed between the rafter boards and drywall or other material is fastened to the face. 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. 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 this case the framer just needed a longer rafter. Roof joists are found on low slope roofs slope of 2 in 12 or less. 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. They may carry ceiling loads.

Called according to its position or use binding joist bridging joist ceiling joist trimming joist etc. Their functions are similar to rafters. Pictured at left is a 2x6 rafter spliced together using 3 4 plywood. Joists are traditionally made from timber.

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. Rafter boards are fastened to the ridge board at the peak and the top plate where they join the wall. 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. To make into rafters as timber.