3 Reasons Why Your Flat Roof Is Leaking (& How To Fix It)

As a conscientious commercial property owner, the thought keeps you up at night: “Why is my flat roof leaking? Was it something my facilities crew did? Something they did not do?” Before despairing (and losing more sleep), investigate these three possible causes. 

Below are Possible Reasons Why Your Flat Roof is Leaking


A depression in your low-slope roof will, thanks to gravity, collect water after any precipitation. The insulation could be compressed. The roof deck’s structural members could be weakened, rusted (if metal), or broken (if wood). Your building could have settled. 

The cause of the depression matters less than your plan to repair it. Ponding is a vicious cycle that worsens with time. Why? Ponding means water sits on the surface of your roof, adding weight. Over time, repeated episodes of ponding further compress the insulation. The depression gets deeper and larger. The pond gets bigger and heavier. 

A reliable, local roofer will repair ponding damage by first diagnosing the cause. It may well be the insulation alone. It may be that insulation is a symptom of another problem further down. 

After satisfying you (and themselves) that the roof deck is in good shape, the roofing crew will replace compressed (probably soggy) insulation. They will take the time to properly slope it to match the correct roof profile. This may involve removing a single-ply membrane or built-up-roofing (BUR) layers. But the repair is well worth this disruption to the roof’s integrity.

With time, ponding can lead to actual plant growth, with small trees, weeds and other invaders taking advantage of the artificial lakefront on your roof. Investing in professional, experienced commercial roofing services will prevent ponding. 

Environmental Causes

If ponding has been ruled out and still you ask, “Why is my flat roof leaking?”, you may be suffering from environmental causes, such as:

  • High heat
  • Direct sunlight
  • Heavy rains
  • High winds

Many types of roofing materials can dry out and become crazed or cracked under ultraviolet rays (sunlight) and radiant energy (the sun’s heat). Miami’s tough climate is especially tough on low-slope roofs. The wide expanses, sometimes made with dark materials, are completely exposed to all Mother Nature has to offer. 

Add the force of high winds (often from hurricanes) and the hard rains that seek out every weak spot in a low-slope roof, and you have environmental issues that can lead to major leaks. 

Seams may look watertight. Flashing may seem secure. But without the expertise of your local roofer’s highly trained crew, you will not know if your roof really is ready to take on the environment. 

Solutions for environmental issues on roofing vary. Your roofer may replace flashing, remove old and brittle caulk and re-caulk with fresh, UV-resistant caulk, or suggest coating a crazed and cracked roof with a waterproof coating

Membrane Mayhem

Single-ply membrane is a cost-effective, long-lasting solution for many Miami businesses. Yet even single-ply membrane may be the culprit when you ask yourself, at 2 in the morning, “Why is my flat roof leaking?”

Single-ply membrane is tough, but it is not impenetrable. Punctures can happen for many reasons:

  • Workers’ boots as a third-party vendor twists and turns on the membrane
  • Dropped hand tools, or (worse!) dropped power tools
  • Changing out rooftop add-ons (radio masts, HVAC equipment, signage)
  • Chemical damage from paint remover, paint, acetate, or other liquid chemicals

Poorly repaired or damaged membrane can also lead to water infiltration. Using the wrong adhesives or patching material is often the reason for a call to a competent, local commercial roofer. Many times, your roofer has to undo the damage caused by bad repair work. 

Another consideration is the age of your membrane. While membranes last for decades, they are not eternally young. Especially under Miami’s hot sun, a single-ply membrane can age rapidly. It grows brittle, losing its ability to expand and contract under thermal changes. Any mechanical fasteners, unable to move with the flexing membrane, will tear elongated holes in the material. 

Depending on the severity of your membrane problems, your roofer may suggest replacing portions of, or the entire membrane. Reflective, waterproof coating may solve some leak concerns. Some chemical sealants may be sufficient to fill tool punctures. 

Choosing a Roofer in Miami

Work only with an experienced roofer to address these three main causes for water infiltration. You may be tempted to use in-house facilities crews or subcontract the work to a general contractor. 

Usually, though, a low-slope roof calls for a trustworthy roofing partner. Shift the responsibility and expense to your local roofer, and save yourself headaches, excuses, and more leaks. A regular maintenance program can even prevent leaks from happening in the first place. 

Call A-1 Property Services today at 786-755-1509 or simply contact us online to learn more. You can stop worrying about a leaking roof when you partner with us.