Ceiling Joists Vs Rafters

They are 2 inches wide and come in a variety of depths from 8 to 12 inches.

Ceiling joists vs rafters. Similarly ceiling joists are the planks of wood that create the flat surface of your attic floor or top story ceiling. 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. Joists are traditionally made from timber.

Then on a flat roof with the same member holding a ceiling on one side and a roof deck on the other is it a joist or a rafter. Joists are traditionally made from timber. In this case the framer just needed a longer rafter.

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. Pictured at left is a 2x6 rafter spliced together using 3 4 plywood. 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.

They are important load bearing structural elements. 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 major functional difference between the two is that trusses are built mostly with 2x4s in place of the wider dimensional boards.

The other common case is the cathedral or vaulted ceiling. Without the tie at the bottom the rafters must be supported at their upper end to prevent the rafter thrust at the lower end. 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.

The load resisting concepts of the vaulted ceiling are completely different. Are they ceiling joists or floor joists. The main difference between joist and rafter is that the joist is a horizontal structural element transferring load from flooring to beams typically running perpendicular to beams and rafter is a structural members in architecture.