Patching a leaky flat roof

Because a flat roof cannot get rid of the water, it is prone to leaks. Repairing the leaks is easy, the hardest part is to identify the affected area. Some of the tools and materials that you will need are:

  • Chalk
  • Ladder
  • Large broom
  • Drilling with screwdriver bits
  • Tin snips
  • Tape measure
  • Chisel
  • Small brush
  • Hammer
  • Garden hose
  • Roof flashing
  • Roofing cement


Before beginning the repair, you will need to do some cleaning.

Remove any debris from the roof, like dirt, leaves, twigs. Inspect the entire area and see if there is more than one leak. Cleaning the roof will help you faster identify the leaks and also the cement won’t stick to dirty surfaces. Look for holes and teared surfaces.

Damaged flashing

Leaking flashing can be removed with the help of an electric screwdriver. Use a hammer to unstuck it and then use a stiff brush to remove the debris and identify the leak. Look for soaked materials. If so, then cut those areas.

Roofing cement

Force the cement under the flashing so that it will cover all the cracks. To secure the leak, the cement should cover an area 3 inch larger then the leak. Wait 15 minutes for the cement to set. If you have cut pieces of roofing material, then replace them and then apply the cement. Add an inch to the replacement pieces.

Replacing the flashing

The flashing needs to be at least 2 inches larger than the area you are covering. Use long screws to fix it tightly.


Read the instructions provided by the cement manufacturer. You will need to let it cure and then water it with a garden hose.

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