Roof Joist Framing

Common i joist applications i joists are used extensively in residential floor and roof framing.

Roof joist framing.

For low pitch roofs building codes may require larger dimension rafters. For instance if your roof has a steep pitch you may be able to use 2 inch by 4 inch rafters but if your roof has a low pitch building code may require that you used 2 inch by 6 inch or 2 inch by 8 inch rafters. Depending on loads and spans c joists are typically spaced at 12 16 19 2 or 24 on center spacing. In most regions the first thing to consider before sizing the wood framing members for a roof is the maximum snow load that the roof will have to bear.

Because i joists are straight and true it s easier for builders to avoid crowning and maintain a level framing surface. These span tables assume installation of at least three joists or rafters that are spaced not more than 24 on center. All roof framing tables are organized by maximum snow load. Initially we will discuss the framing of gable roofs so that we can learn the basics of how to size a roof rafter beam or joist.

They are ideal for long spans including continuous spans over intermediate supports. Instead a wood i joist roof system is framed with either a central bearing wall or a structural ridge a beam that carries the roof load to posts. This will give the framing square the angle you need to make the ridge cut. Rafter and joist span faq the lengths and sizes of joists vary depending on the species and quality of the lumber used.

Structural track usually in the same gauge as the. The load from the top half of the roof is carried by the bearing wall or structural ridge. If you plan to have eaves to protect the shed walls make sure you add the extra length when measuring the rafters. Corbett grace their parents and even their kids are learning a lot about the many ways a few right many wrong to build a high performance home.

For example you can span a 1 grade no knots southern yellow pine a greater distance than a 2 grade with knots southern yellow pine. For all species and grades of nominal 2 inch framing lumber customarily used in construction. So if the pitch of your roof is 7 12 place one stair gauge on the vertical part of the framing square the tongue at the 7 inches 18 cm mark and place one stair gauge on the horizontal part of the framing square the body at the 12 inches 30 cm mark. The calculated spans assume fully supported members properly sheathed and nailed on the top edge of the joist or rafter.