A porch roof is a relatively simple addition to your home's exterior. It adds shade on hot, sunny days and shelter when it is raining. With the correct tools and materials, constructing a porch roof can be done on your own for much cheaper than it would cost to hire a carpenter. Basic porch-roof building instructions can be changed or expanded on depending on the specifications and size of your porch.
Evaluate the structure of the porch and the side of the house where the roof will be attached. Make sure everything is level and that the wood is in good shape.
Draw out your plan and determine the dimensions of the roof and how tall it will be. Design your porch roof to have the same or similar pitch as your house's roof in order to maintain architectural continuity. Plan for an overhang. Overhangs are generally 12 to 17 inches. You may want to match the length of the overhang to the overhang of the roof on your home. Consider any electrical needs you have.
Measure and nail a 2 x 6 or a 2 x 8 ledger board to the side of the house, perpendicular to the porch floor. This is what the back end of your rafters will be attached to.
Measure, cut and attach posts to the supports at the base of the porch. Attach posts by toenailing them into the porch supports, bracing them and using post connectors. Make sure they are vertically level.
Once the posts are all in place, attach top plates. Use either 2 x 6s or 2 x 8s.
Level and nail the roof trusses. These should be placed every 24 inches, measuring from the centre of each board. Set the end truss flush with the top plates of the end walls. Metal braces can also be used to connect the trusses to the top plates of the end walls.
Measure, cut and attach 2 x 4 or 2 x 6 rafters. Use metal connectors to attach the rafters. Place rafters every 16 inches.
Sheath the top of the rafters with 1/2 inch or 5/8 inch plywood and cap the ends of the overhang rafters with 2 x 4s or 2 x 6s.
Cover the gap between the porch roof and the side of the house with flashing (to keep out water); tarpaper and shingle your porch roof. Choose shingles that will match the shingles on your house.