How to Fix a Leaking Balcony Flat Roof

Although roof balconies provide outdoor space for relaxation and entertainment, they are susceptible to damage.
Flat balcony roofs require proper maintenance.Flat balcony roofs require proper maintenance.
Exposure to ultraviolet sun rays, freezing temperatures and other weather conditions eventually cause roofing materials on flat balcony roofs to split and crack, which allows water seepage indoors. Projections, such as various plumbing pipes and chimneys, on flat roofs may also leak around the edges. Leaking portions of flat balcony roofs require immediate patching to ensure home interiors don’t acquire moisture damage.

Step 1

Scrub the leaking sections, such as cracks and around damaged projections, with a wire brush to detach crud. Sweep all grime off the balcony roof using a broom.

Step 2

Put on full-length clothing, eye protection and rubber gloves. Many roof patching compounds, such as plastic cement, contain toxic chemicals.

Step 3

Spread plastic roof cement around a leaking roof projection using a trowel. Make the cement bed 1/8-inch thick and spread three inches beyond the projection. Don’t let the roof cement dry.

Step 4

Lay fiberglass reinforcing fabric over the moist bed of cement. Using the trowel, press the fiberglass fabric into the cement.

Step 5

Coat the fiberglass fabric with a 1/8-inch-thick layer of roof cement. Use the trowel to smoothly spread the cement three inches beyond the projection, making the cement layer thinner toward the edges of the repair.

Step 6

Let the sealed roof projection cure for three days.

Step 7

Coat a crack in the balcony roof with a 1/8-inch-thick layer of rubberized roof patching cement using the trowel. Extend the rubberized cement three inches beyond the crack.

Step 8

Lay fiberglass reinforcing fabric over the moist bed of rubberized cement. Using the trowel, press the fiberglass fabric into the cement.

Step 9

Coat the fiberglass fabric with a 1/8-inch-thick layer of rubberized cement. Use the trowel to smoothly spread the cement three inches beyond the crack, making the cement layer thinner toward the edges of the repair.

Step 10

Let the patched crack cure for two days.

Things You Will Need

  • Wire brush
  • Broom
  • Full-length clothing
  • Eye protection
  • Rubber gloves
  • Plastic roof cement
  • Trowel
  • Fiberglass reinforcing fabric
  • Rubberized roof patching cement

Tip

  • Clean up plastic roof cement and rubberized roof patching cement with mineral spirits.

Warnings

  • Some chemicals in plastic roof cement and rubberized roof patching cement may cause serious health issues, such as cancer or reproductive damage.
  • Plastic roof cement and rubberized roof patching cement are flammable and toxic.

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.