How to Find Water Leaks on a Flat Roof

Flat roofs are recognised for their affordability, simple accessibility and modern architecture. However, accumulated dirt, moss and debris can prevent water from properly draining from a flat roof, causing leaks. Leaks are also often due to worn or damaged roof coatings and materials. Since water flows in any direction on flat roofs, leak sources are sometimes unpredictable. Flat roofs require consistent maintenance to prevent leaks and preserve a home's structural integrity. Properly locating leaks is necessary before attempting reparations. Use basic techniques to effectively find water leaks on a flat roof.

Put on slip-resistant shoes for safety purposes. Access the roof using a sturdy ladder.

Inspect the metal flashings surrounding any plumbing stacks, skylights and chimneys for cracks. Study the flashings at the edge of the roof for cracks, openings and broken seams.

Evaluate the entire roof surface for low spots and evidence of water weight. Look for circles of dirt on the roof, which indicate evaporated water. Inspect the inside of the circles for small holes.

Examine the seams in the roofing material for holes and cracks. Inspect the roofing material for flaking, cracks, holes and corrosion.

Inspect the roof for accumulated tree branches, moss or other debris. Sweep away the debris with a push broom. Inspect the affected area of the roof for deterioration, cracks and tears.

Test the roof for leaks using water from a garden hose. Apply water to low spots and other potential leaking areas of the roof. Wait 10 minutes for water to begin leaking into the house. Trace the leak to the water-filled low spots on the roof.


Do not access the roof during windy or icy weather conditions, as it is unsafe. Contact your roofing manufacturer or installer for proper roof maintenance and repair techniques appropriate to your roofing material.

Things You'll Need

  • Slip-resistant shoes
  • Sturdy ladder
  • Push broom
  • Garden hose
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About the Author

April Dowling first started writing in high school and has written many news articles for newspaper and yearbook publications. She is currently pursuing a career as an online writer and affiliate marketer. Dowling writes for several websites and keeps many blogs.