Ceiling Layout and Framing
After you assemble and erect the walls, what is the next step? Traditionally, in a one-storey building, carpenters would install ceiling joists on top of the structure, spanning the narrow dimension of the building from top plate to top plate. Then, if the carpenters intended to build a common gable roof, they would install rafters that extend from the ends of the ceiling joists to the peak, forming a triangle.
Ceiling joists have two important purposes:
• Joists are the top of the six-sided box structure of a building. They keep opposite walls from spreading apart.
• They provide a nailing surface for ceiling material, such as drywall, which is attached to the underside of joists.
Cutting and Installing Ceiling Joists
1. The joists must be cut to proper length, so that the ends of the joists are flush with the outside edge of the double top plate.
2. Allow enough extra length for any overlap of the joists above the bearing partitions.
3. Cut the ends of the joists at an angle matching the rafter pitch. This is done so that the roof sheathing lies flush on the roof framing.