Sub Floor Construction Details

The subfloor is the bottom most layer and it rests on the joists.

Sub floor construction details.

If you have a concrete slab floor the slab may be considered the subfloor. Beams are thicker and longer and are laid vertically. Typically made of plywood or osb and ranging in thickness from 19 32 to 1 1 8 thick the subfloor is truly structural second only to joists in this respect. Although cold formed steel framing for floor systems also is permitted by the irc it is not covered here.

Joists are typically shorter and lay across the beams to give them horizontal support. Or the subfloor may be made of plywood or other panel products that are laid perpendicular to the joists. Beam and joist arrangements can form a supporting frame for a floor. Rather the reader is referred to the aisi standard for cold formed steel framing prescriptive method for one and two family dwellings aisi 2001 for guidance.

On wood frame floors the subflooring provides a continuous structural surface over the floor joists. 69 chapter 4 floor construction woodframe floor systems and concrete slab on grade floors are discussed in this chapter. It may be made of boards laid either at right angles or diagonally across joists. Subflooring provides a base for finish flooring and also serves as a platform during construction.

Good subfloor construction depends on material selection and attention to critical details.