Adding a roof to your porch provides you and your porch with much-needed protection from the sun, wind, rain, snow and ice. In addition, your new porch roof can boost your home's curb appeal. However, you must ensure that the new porch roof matches with your existing roof seamlessly to enjoy these benefits. If you have basic carpentry skills, and understand basic framing techniques, you can connect a porch roof to the house.
Attach a sill plate to the house in between the porch's two side supports. The sill plate should sit flush to the top edges of the roof support columns.
Position the rafters on top of the sill plate. Joist hangers can help you mount each rafter to the house, and you can use screws to secure the rafter to the sill plate. The positioning of your rafters depends on the porch roof's pitch. You might decide to build it so it matches the pitch of your home, or you might decide to do a shallow roof pitch. If you decide on a shallow pitch porch roof, use 2-by-6-inch rafters.
Frame your porch roof by continually adding rafters until it extends 1 foot past your porch walls or support columns. A fascia board will mount on the front and on the sides of your porch roof frame.
Cover your rafters with thin sheets of plywood. Hammer the plywood into the rafters until it's securely in place.
Use roofing materials that match your existing roof. As long as you use a roofing design that matches your existing roof, you can use the same materials. However, if you deviate from the plan and build a porch roof with a peak larger than your existing roof, check to make sure the pitch profile is still compatible.
Add your roofing materials to your porch roof starting at the house and working your way out to the edge of the porch. It may be necessary to pull some of the shingles off your house so you can create a seamless pattern onto your patio roof.
Check your local building codes before you begin construction. You might also need a building permit before you begin working on your porch roof.