How to Add a Lean-To to a Patio Roof

A lean to.
  • 4-5 hours
  • Intermediate
  • 1,500
What You'll Need
Extra roofing sheets (optional)
Measuring tape
Long saw
Metal cutter
Concrete mixture
Rag cloth
Rafters square
Spirit level
String line

A patio roof not only offers shade, but also protects your outdoor living space from the sun, wet weather, and other elements. Adding a lean-to the patio roof will enhance the aesthetic appeal of your home and offer you more protection from accumulating rainwater and snow. Before you begin this project, consider whether the existing structure holding your roof is strong enough to support a lean-to.

Step 1 - Get Permission

To begin, contact your local planning and zoning department to obtain details about the codes and regulations related to the addition of a lean-to the patio roof. If necessary, draw a design depicting the dimensions of the lean-to and attain permission from this department.

Step 2 - Purchase Required Materials

Measure the existing structure with a tape measure to determine the length of the posts you will need. As you are going to give a lean-to the existing roof, you have to give the roof a slope by angling the rafters that sustain the roof.

Step 3 - Fix the Posts

Dig holes and place the posts. Fill 6 inches of each hole with concrete mixture, and place the post vertically. Once the wood is in place, fill the rest of the space with a concrete mixture. Repeat the same for the other end post. Then tie a string line to use the level as a guide for fixing the other posts.

Step 4 - Determine the Slope

Use the string line to determine the angle of the slope you want to give to your patio roof. Once you are satisfied with the slope, mark the rafters on the outer posts. After this, you may have to trim the new posts to form the necessary slope.

Step 5 - Place Rafters

Notch the post tops so you can place the rafter nailer on them. Place the rafters one by one in the marked positions on the posts with a uniform gap between each rafter. Check the layout of the rafters by simply placing and looking at them before shooting in the nails.

Step 6 - Check the Slope Angle

Use the speed or rafter’s square to check the angle of the slope you wish to add to your patio roof. Cut the outer end of the rafter at the angle you measured. Once the slope is satisfactory, you can tighten the nails using a toenail method on both sides of the rafters.

Step 7 - Place the Roof

Finally, place the roof on the newly set rafters, and see if the length of the roof sheet is sufficient. Once the sheet has been placed snuggly, secure the roofing sheet with nails and fasten tightly.