How to Connect a Lean-to to a Roof

Set up a ladder next to your home where you plan to install the lean-to. Inspect the edge of the roof where you wish to continue the roofline with the lean-to.

Remove any gutter components along the edge of the roof by removing the screws that hold them in place, or pulling out nails with a claw tooth hammer. Remove the roof's fascia, which is the vertical facing that covers the end of the roof structure, revealing the wooden trusses.

Remove the ladder. Position the lean-to in place next to your home. Ensure that the depth of your footings and the height of the lean-to's posts cause the lean-to's roof frame to line up with the exposed trusses of your home's roof. Adjust the lean-to's placement as needed.

Set up a ladder under your lean-to's roof. From below the roof, note the location of trusses where they abut the lean-to's roof frame.

Drill through the lean-to's roof frame and into the end of each truss using an electric drill with a 1/4-inch bit.

Insert 1/2-inch lag bolts into each of the holes you drilled in Step 5, tightening them with a 1/2-inch socket and driver.

Access your home's roof and move to the area where the roofing material creates a seam where it meets the lean-to's roof.

Nail asphalt shingles in an overlapping pattern along the length of the seam using roofing nails and a hammer.