Roof Ceiling Joists

Standard size of joists.

Roof ceiling joists.

The roof joist is what makes up the ceiling of a home. Ceiling joist loads ceiling joists are sized based on one of two tables found in the code. The first surface is unsurprisingly the ceiling the materials of which attach directly to the joists. A broken roof joist is a serious problem that must be taken care of immediately.

Ceiling joists provide support for more than one surface in your home. Ceiling joists of the first floor of a two story structure often serve as floor joists for the second floor. They are spaced according to the material they support. Before we look at these tables we need to make sure the correct design loads are determined prior to selecting the correct table.

If this is the case with your structure use the floor joist table to determine maximum joist length load. 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. The other surfaces are the walls which the joists span the distance between providing a source of support to keep the walls from shifting. Ceiling joist spans for southern yellow pine douglas fir and eastern spruce.

The joists are horizontal pieces of lumber that span the distance from one side of the home to the other. These span tables list allowable ceiling joist spans for common lumber sizes based on what design load scenario is applied. Joist span tables use these tables to determine lengths sizes and spacing of ceiling joists. Typically the material is plasterboard which can span 450 mm.

Ceiling joists are normally horizontal members however under special circumstances they can be fixed on a slope. 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.