What's a Ceiling Joist?

Ceiling Joists are the horizontal members that provide a structure to fix the ceiling, and support and fix the diagonal rafters that define the roof shape and are attached at the top to a ridge beam. In many modern constructions the ceiling joists are substituted by the bottom cord of a factory manufactured truss.

How do you find a ceiling joist?

Hold a flashlight right by the ceiling on a very gentle angle to the surface, so the light shines nearly horizontally across it. Look for dimples in the paint. They usually indicate the presence of a nail behind the plaster, and where there's a nail, there's a joist.

What is one purpose of a ceiling joist?

The ceiling joists have a double function: they provide the structure onto which the ceiling is fixed. they are the member that connects or ties the lower ends of rafter couples (pairs). Therefore, they prevent the rafters spreading and causing the roof to sag or collapse.