Roof Joist Thickness

There are several variables to consider when determining the proper rafter size.

Roof joist thickness. Minimum thickness most roofs will be sheathed in plywood at least 3 8 inch thick. Thickness generally improves floor. Standard asphalt shingles add very little thickness to the roof because a standard three tab shingle is about 3 16 inch thick. Structural track usually in the same gauge as the joist is used as rim or band enclosures.

This sizing guide for roof rafters will help determine what you need for your small project. Span calculator for wood joists and rafters also available for the android os. Though there is no standard joist size for the ceilings in all buildings most average homes use ceiling joists in a board size of 2 by 6 inches. Weather you re building a shed roof or adding a dormer to your second story it is important to choose the proper size rafter.

Depending on loads and spans c joists are typically spaced at 12 16 19 2 or 24 on center spacing. Another option are 2 x 8 rafters spaced 24 inches o c. Usually 400 450 or 600mm but any value can be used up to 610mm max 1 2 timber strength class and joist size automatically calculate sizes suitable for supporting the loads below. This is the distance between joist centres.

The table states that 2 x 6 rafters spaced 16 inches on center o c can span a maximum distance of 13 feet 5 inches. That will suffice on a roof with rafters set 16 inches apart with minimal roof loads. In making your choice consider how you will insulate your insulate your roof. Ceilings directly applied to the bottom edge of the floor members or equivalent 1x or 2x strapping is a.

Also available for the android os. Featuring trus joist tji joists for floor and roof applications. The range of joist sizes used in homes varies though between 2 by 4 inches and 2 by 12 inches.