How to Put a Roof on a Patio

Patios are often used as outdoor living rooms, complete with furniture, plants and decorations. The main problem with patios is their vulnerability to the elements. When it rains, patios and everything on them get wet. When it is hot and sunny out, everything on them roasts. It is a relatively simple matter to put a roof on a patio to allow it to be enjoyed under a wider range of weather patterns.

Things You'll Need

• 6x6 posts
• Concrete
• Shovel
• J Bolts
• Metal post bases
• 2x8 boards
• Plywood
• Shingles
• Saw
• Caulking gun and caulking
• Drill and screws
• Hammer and nails
• Water proof roofing membrane
• Peel and stick roll roofing
• Roof flashing

Instructions

1. Dig footers at the corners of the patio opposite the house. They should be roughly 12 inches in diameter and 24 inches deep. For patios 14 feet or less in length, two holes are all that are needed. For patios larger than that dig another footer hole in between the two corner holes.

2. Fill the footers with concrete, making sure to pack it down in the hole with the shovel so that there are no voids in the footer.

3. Place a J-bolt in the middle of each footer, leaving approximately 3/4 inch of the threads above the surface of the concrete and the J end buried in the concrete. Let the concrete footers cure for 48 hours.

4. Place a metal post base on top of each footer. Insert the washer and nut that came with each post base on the exposed threads of the J-bolts and tighten down.

5. Cut the posts to eight feet in length. On one end of each post, cut a notch that is three inches deep by 11 1/4 inches long. This notch will fit the double 2x12 beam that will hold the roof rafters.

6. Insert the bottom of the first post in a post base. Nail the post base flanges to the post to secure it to the footer. Repeat as needed to install the other posts. Brace the posts by nailing two 2x4 scraps to the post at right angles to each other. Secure the scraps by driving stakes in the ground near the other end of the scraps and nail the scraps to the stakes.

7. Mount the first 2x12 on the posts. Let it overhang the edges of the patio by 12 inches. The 2x12 should sit in the notch created in Step 5. If the patio has three posts, cut the 2x12 to land two inches from one side of the middle post and install another 2x12 that runs from the middle post to the last post, overhanging the patio edge by 12 inches.

8. Install the second 2x12 by nailing it to the face of the first 2x12 to create the beam. If a third post is used, cut this 2x12 to overlap the joint in the first row of 2x12 by two inches in the other direction of the post and install a second 2x12 to complete the row.

9. Mark the house wall where the rim joist that will support the roof rafters will go. The top of this joist should be located 9 feet above the patio and the sides should extend one foot beyond the edges of the patio. Install the ledger board by screwing it into the wall studs or rim joist of the house.

10. Place the 2x8 rafters starting from one end of the rim joist and move toward the other end. They should be spaced 16 inches apart. Nail the top end of the rafters into the ledger board and nail the other end into the beam on top of the posts. Let the rafters overhang the beam by 12 inches. Make sure to start with a rafter flush with the edge of the rim joist and beam end and to finish with a rafter flush with the rim joist and beam end on the other side of the roof.

11. Nail plywood on top of the rafters to create the roof decking. This plywood should be overhang the rafters on the edge of the roof and the end of the rafters by one inch.

12. Apply a layer of peel and stick self sealing water proof membrane to the top of the roof. Start at the bottom and work towards the top, with each row overlapping the row below it by four inches and running from side to side. The membrane should be trimmed flush with edges of the plywood.

13. Nail aluminum roof edge flashing along the perimeter of the roof. The flashing should sit on top of the water proof membrane. The membrane will automatically seal around any nails that puncture it.

14. Apply the final self stick roll roofing. Start at the bottom of the roof, just like with the membrane and work toward the top of the roof, this time covering the top of the flashing and overhanging it by one inch. This roll roofing comes in three foot wide rolls and is similar in texture to shingles. Do not skip this step as the membrane will not withstand the sun and will break down.

15. Install flashing behind the siding and on top of the roll roofing where the roof intersects with the wall. Do not nail the flashing to the roof. Instead, remove the course of siding and nail the flashing to the wall and then replace the siding over it. If the house has brick siding, use a grinder to score a line from one side of the roof to the other, about a 1/2 inch deep. Use brick flashing and insert the top bend of the flashing into the scored line. Before installing the brick flashing, run a couple of beads of adhesive on the brick between the line and the roof. Then run a thick bead of caulk in the scored line. Once the brick flashing is installed, run another bead of caulk on top of the flashing where it goes into the brick.