Porch Roof Rafter Spacing

So the space between rafters can be greater without reducing the maximum span.

Porch roof rafter spacing.

This table agrees that 10 12ft is the max span for typical grade lumber at typical spacings for a 5psf dead load. If your project had a rafter length of 8 or less a safe and strong method is to use 2x8 framed 16 on center. As a general rule roofs that have a high human occupancy rate should be framed with rafters every 16 structures such as sheds or barns can be frames with rafters every 24 again make sure to consult local codes. Squaring the beams and bracing them to ensure the maintain square is essential to the roof building process.

The same concept holds true for roof trusses. Maximum rafter spans for a patio roof in areas with mild climates patio roofs are generally designed for loads of 30 psf pounds per square foot. Common spacing for trusses on this type of building is often between 2 and 4 feet but trusses built with advanced designs may allow spacing as great as 8 or 12 feet. Rafters must be strong enough to hold the roof sheathing and the shingles.

Once the beams are in place mark the spacing for the trusses normally 16 inches apart. The minimum pitch for a roof is 1 4 12 which translates to 1 4 inch rise to 12 inches of run. If your local building authority has a rafter spacing code you may not space rafters wider than required by code. Typical rafter spacing codes will specify a minimum spacing of 16 inches 19 2 inches or 24 inches.

Subtract that number from the width of the panel and then divide by 2 to come up with the spacing for the rafters. However you can only use this pitch with built up roofing or specialized synthetic roofing. A 4 by 10 can usually span up to 12 feet between posts. An essential part of planning a patio roof or gazebo project is determining the number size and spacing of rafters beams and posts according to the loads they will carry.

Both 16 inches and 24 inches are common measurements for rafter spacing. In general the maximum span for a 4 by 6 beam is 6 feet between 4 by 4 posts. If you move up to 4 by 8 you re usually allowed to span up to 10 feet between posts. If this calculator from the american wood council is to be believed and if my assumptions about your materials and load are correct the max span is about 10ft for a pine 2x6.

Double the hill and valley width since this is the amount that the panel will overlap the one next to it on each side.