How to Replace a Flat Roof Covering

Replacing Felt

• 1

  Remove all old nails from the timber using a claw hammer and pull up the old felt. If any nail heads break off, hammer the remaining nail below the surface of the wood so it does not rip the new felt. Also, check the strength and condition of the timber to ensure it is not rotting.

• 2

  Measure the roof's dimensions. Use a razor to cut strips of felt to cover the entire roof, allowing for 50 millimeters of overlap on every side to help prevent against leakage.

• 3

  Nail the felt along one edge of the roof using the galvanized clout nails. Start in the middle and work toward the edges, spacing the nails approximately 150 millimeters apart.

• 4

  Overlap the next layer of felt by 50 millimeters and snap a chalk line along the edge. Brush felt adhesive in this 50 millimeter area the entire way down the felt. Affix the second piece of felt to the adhesive, ensuring that all air bubbles are removed, and then nail the short ends of the felt to the roof perimeter. Repeat this process until the entire roof is covered and the perimeter is completely nailed down.

• 5

  Apply a layer of waterproof mastic sealer over the top of the felt for protection against water damage. For extra protection, repeat Steps 1 through 4 again to create a second layer of felt and then apply sealer to the top of this additional layer as well.

Replacing Rubber

• 6

  Use a heat gun to melt the adhesive along the edges of the old rubber covering. Cut the old covering into manageable pieces using a razor and pull them up. Check the quality of the timber to ensure it is not rotting.

• 7

  Measure the roof's dimensions. Use a razor to cut strips of rubber membrane that will cover the entire roof, allowing for 50 millimeters of overlap on every side, just like with felt. Allow the membrane to flatten out in the sun for an hour.

• 8

  Use a paint roller to apply neoprene liquid or latex adhesive to the underside of the membrane. Smooth and remove any excess with a trowel. Lay the membrane out along the edge of the roof, with an overhang of about three inches.

• 9

  Overlap the next layer of membrane by 50 millimeters and snap a chalk line along the edge. Brush adhesive to the underside of the membrane and affix this second piece to the first along the chalk line, ensuring that all air bubbles are removed. Repeat this process until the entire roof is covered.

• 10

  Seal the three-inch overhangs on all sides of the roof with adhesive. Also, apply a layer of waterproof mastic sealer across the top of the membrane to protect against leaks and water damage.