DIY: Patio Roofs

Mark the locations for posts, at all four corners of the patio and at 4-foot intervals, or 8-foot intervals for a larger patio. Measure corner to corner with a tape measure and compare diagonal measurements, adjusting post locations until the diagonals are the same so the patio outline is square. Use only corner posts for a patio with less than 10 feet in length and width.

Dig holes with a post hole digger for posts, 4-by-4-inch or 6-by-6-inch, depending on the size of the patio. Make holes about one-third the height of the finished post; set 10-foot posts a little over 2 feet deep for an 8-foot-high roof frame. Slope the tops of the posts so one end is at least 4 inches higher than the other, sloping in a direction to best drain water away from the patio.

Plumb the posts with a level and fill the holes with concrete, mixed in a wheelbarrow using a prepared mix with gravel in it. Tamp the concrete solidly around the posts with a 2-by-4-inch board. Extend it to just above ground level and slope it away from the post. Let the concrete cure for about three days.

Put beams across the tops of the posts in the direction of slope. Use the same size lumber as the posts and toenail beams to the posts with 16d framing nails driven diagonally into the posts with a hammer. Use a circular saw to cut supports on both sides of each post; cut 45-degree miters and nail the braces to the side of the post and bottom of the beam.

Use metal joist hangers to install rafters the width of the roof, the space between beams. Fasten hangers to the beams with 8d galvanized nails, set 2-by-4-inch rafters in the hanger slots and nail rafters through holes in the sides of the hangers. Space rafters with centers 24 inches apart the length of the roof.

Cover the roof with corrugated metal or vinyl panels perpendicular to the rafters or with oriented strand board decking for a shingled roof. Install corrugated panels with screws that have plastic or rubber washers on the heads to seal the screw hole. Drive them with a screw gun until the washers are tight against the panel but do not compress it. Install OSB with 8d galvanized nails, then add roofing paper and shingles.