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How to Fix a Flat Roof

While flat roofs offer a unique aesthetic, they don’t drain water as well as sloped roofs. This means if you have a leak, it’s important to address it quickly. Today, many flat roofs are made from a rubberized material. In this how-to, our roof repair experts explain how to fix a flat roof.

Locate the Leak

  1. From inside, locate the leak.
  2. Next, use a measuring tape to measure the distance between the leak and the two nearest walls.
  3. After that, set up your ladder against your home and climb up to your roof.
  4. Use the measurements you took to locate a general area of where the roof leak may be.
  5. Look for imperfections in the roofing material that may be causing the entrance of water.
  6. If you can’t find anything in the material, examine the nearby flashing, vent caulking, vent pipe boots, and other structures.

Repair the Damage

  1. Once you’ve located the leak, make sure the area is dried thoroughly.
    1. If you have a hole or puncture, apply rubber sealant to the area.
    2. Use a small putty knife to work the sealant into the hole or puncture and let it dry completely.
    3. If your roof has a membrane blister, use a utility knife to cut the blister all the way across. (Make sure you don’t go deeper than you need to.)
    4. Next, use a towel to dry the area underneath the blister.
    5. Once the area is dry, apply a thick coat of roofing cement to the underside of the blister edges.
    6. Next, press down firmly to close the blister.
    7. To make sure the blister is completely sealed, drive several galvanized roofing nails into it to permanently close it.
    8. After that, apply roofing cement over the nails and use your putty knife to spread evenly.
  2. If your roof has a large rip or tear, we suggest contacting the roof repair experts at P.J. Fitzpatrick. We can repair your roof properly so you can stop your water damage from becoming worse.

Tools & Materials

  • Measuring tape
  • Ladder
  • Rubber sealant
  • Putty knife
  • Utility knife
  • Towel
  • Roofing cement
  • Galvanized roofing nails
  • Hammer

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