The weight of the floor or ceiling covering, along with the size of the span, form the basis for calculating the size joists that are needed. Joists are laid out in parallel and may be supported by ...

type of material, and spacing between the joists. Large floor joists can carry more of a load, and spacing joists closer ...

Where and how to drill floor joists for electrical cables or plumbing runs depends on what type of floor framing you have.