How to Replace the Shingles on a Flat Roof With Rolled Asphalt Roofing

Cut the rolled asphalt roofing with scissors into either two 18-inch lengths or three 12-inch lengths and then roll them backwards loosely about a day before applying them. This helps straighten the rolls so they aren't warped when you apply them. Measure the roof ahead of time with a tape measure so you know how many sheets you'll need.

Remove the nails holding the shingles into the roof by pulling them out with pliers or the back of a hammer. Remove each shingle individually to prevent damage to the roof surface.

Fill all the nail holes with a roofing tar to prevent the risk of water leaks.

Clean the roof by sweeping it with a broom and then spraying it down with a hose to remove any debris that could interfere with the roof laying process. Wait for the surface to fully dry before continuing.

Lay down 15-specification asphalt saturated felt on the roof starting at one corner. Roll the felt across the roof lengthwise in strips, overlapping each strip slightly as you go across the roof to the other side. The felt should hang over the edges about an inch.

Nail one side of the felt into place on the roof and stretch the felt across to ensure it is tight before nailing the other side. Use plastic cap felting nails to prevent roof damage during this process. Place the nails every 12 inches to keep the felt secured.

Cut the excess felt with scissors so you don't have too much hanging off the roof. Cover each nail head with roofing tar to seal each of them before continuing.

Lay down the lower layer of rolled asphalt roofing and nail it in place with galvanized roofing nails. Nail one side down first and then stretch out the sheet before nailing the other side to prevent air pockets. Start on one side of the roof as you did before and work your way across to the other edge, overlapping each sheet several inches with the one next to it. Nails should be used every six inches or so.

Apply a thin layer of roofing cement to the first asphalt sheet with a trowel and then stick the second layer to it. Do not nail the second layer in place. The adhesive bonds it in place, and this prevents greater risk of leaking. Use care to ensure the top layer goes straight across the lower layer without bunching up in the process.

Nail down the overlaps between sheets and apply roofing cement to each nail head to seal it against water intrusion.