Attic Subfloor Thickness

Simple sheathing cdx or underlayment should work fine.

Attic subfloor thickness.

You ll need to make sure that the plywood can fit through your attic door. For the small difference is cost use 3 4 inch sheathing or underlayment. How to build a subfloor in an attic. Standard joist spacing for the installation of attic flooring materials is 16 inches on center oc meaning the distance from the center of one joist to the center of the next joist is 16 inches.

You also need to ensure that the joist spacing is adequate. The difficulty comes from the precise measurement and cutting required and the labor of getting the sheets of underlayment in place. The decision regarding the thickness of plywood to use for the subfloor in the attic has a lot to do with how you intend to use the attic and it also depends on the spacing of the ceiling joists. Attic joists that are made from 2x8s may be acceptable for building your attic floor but because every room is variable there are no absolutes.

Measure the plywood and attic door. Attic joists for live loads. There are several good t g underlayment brands out there but t g may be a little over kill for your application. Purchase half inch 1 27 cm thick plywood to act as your flooring.

Covering part or all of the ceiling joists in the attic is a cheap way to make use of wasted space. Take the measurements for your subfloor and measure enough plywood so that you can cover the entire frame. A subfloor is a stiff wood underlayment secured directly the the flooring joists.