How to Fill in Low Spots on a Flat Roof

If your home has a flat roof, the material used to cover the surface may not last as long as what's used on a sloped roof because rainwater, snow and ice does not easily slide off the roof. Low spots on the roof can develop that may lead to leaks into the interior of the house. You can extend the life of your flat roof through regular maintenance, such as removing heavy snowfall from the roof, replacing damaged areas and filling in the low spots. This will help to keep the roof in good condition and prevent water intrusion into your home.

Ladder
Shop broom
Asphalt roofing material
Roofing cement
Trowel
Heavy shears for cutting
Nylon roofing fabric
Elastomeric coating
Roller

Instructions

- 1
  Inspect the roof carefully to find stress cracks, nail holes or other perforations that could lead to a leak in the roof. Because leaks often occur in the low spots of the roof, ensure that you have repaired any problems in the roofing in these areas before building up the spot.
- 2
  Remove all loose gravel from the low area with a shop broom.
- 3
  Cut a 12-inch circle of roofing material and center it over the low area of the roof. Glue it into place with roofing cement.
- 4
  Cut a larger circle of roofing material, 16 inches in diameter. Cover the surface of the piece entirely with roofing cement and install over the previous piece.
- 5
  Cut another circle 20 inches in diameter, cover it with roofing cement and apply the piece over the previous one, taking care to thoroughly cover the edges of the circle with cement.
- 6
  Continue this process, increasing the diameter of each successive layer, until the low point of the roof is raised to the same level as the surrounding area.
- 7
  Cover the entire area with a layer of nylon roofing fabric cut to size. Then, apply a second layer of the fabric to the area.
- 8
  Roller the elastomeric (rubberized) coating compound onto the top of the fabric, completely saturating it. Spread out the coating several feet beyond the patched area. Allow the compound to dry thoroughly.
- 9
  Spray the patched area with water. No ponding of water should be evident on the patched area.

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