Loft Floor Joist Thickness

This sample table gives minimum floor joist sizes for joists spaced at 16 inches and 24 inches on center o c for 2 grade lumber with 10 pounds per square foot of dead load and 40 pounds of live load which is typical of normal residential construction.

Loft floor joist thickness.

19 32 and 5 8 inch thick panels require joists spaced 20 inches on center. Existing loft joists are designed only to support ceiling boards so a structurally sound floor is needed. If you plan on placing the plywood around the perimeter of the opening or door and using it only to store light boxes or materials 1 2 inch thick plywood should suffice. If the attic joists are not adequate one way to strengthen the floor for live loads is to sister the old joists.

The thicknesses are as follows. Joists insulation and boarding. Ceiling joists consist of two narrow low grade timbers often bolted together sistered above a supporting wall. True floor joist span calculations can only be made by a structural engineer or contractor.

Loft floors loft floor construction. For example if you double the thickness or number of joists in a floor the distance the boards can span will increase by approximately 25. The width of a board is an important factor in determining the distance a floor joist can span playing a much larger role than the thickness. I m building a loft above my garage for storage.

In the case of 2x6 joists you can pair them up with additional 2x6 joists by nailing them together side by side. 7 16 15 32 and 1 2 inch thick panels require joists spaced 16 inches on center. Sistering is the process of adding a new joist next to each existing joist.