Roof Ledger Board Size

If your local building authority has a rafter spacing code you may not space rafters wider than required by code.

Roof ledger board size.

As a rule of thumb bolts can be spaced 16 on center for supporting joist span up to 12 in length. It is always better to have a large rafter rather than be concerned with a sagging roof. Our roof rafter calculator tools are handy for calculating the number of rafters needed rafter length calculator lineal feet of rafter board feed in ridge and sub facia and the total board feet in the roof. If your project had a rafter length of 8 or less a safe and strong method is to use 2x8 framed 16 on center.

This means the example porch would need a 6 inch by 8 inch beam. It should be 6 8 inches above grade ideally but you can get ground contact pt that can be placed closer. X 9 in. Calculate the initial value for d then round it up to the nearest inch.

Ledger the same size as the rafters and fastened to the studs with x5 lag screws spaced page 2 of 6 at 32 maximum on center for up to a 10 0 rafter span. Lag screws may be spaced at 16. Douglas fir lvl no attachment is allowed to strand lumber syp lvl the mudsill i joists floor trusses or other materials. House rim joist must be minimum of 2x sawn lumber or 1 in.

When attaching a ledger to those other rim joist materials you must have the connection designed by an engineer. You want a flashing that won t react with. Rise and run means that a 6 12 pitch roof has 6 of rise vertical for each foot of run horizontal. The closer the rafters are to each other the stronger the roof will be.

Typical rafter spacing codes will specify a minimum spacing of 16 inches 19 2 inches or 24 inches. In the example d calculates to 7 75.