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Why Does a Flat Commercial Roof Leak When It Snows, But Not When It Rains?

snow on a flat roof

Flat commercial roofs can present unique challenges, especially during the winter months. You might notice that your roof is perfectly fine during heavy rain, but the roof leaks when snow melts. This discrepancy can be puzzling, but it’s often due to the distinct way snow interacts with your roof compared to rain.

Factors like snow accumulation, freeze-thaw cycles, and the roof’s drainage system all play a role in causing leaks during snowy conditions. Understanding these issues can help you better protect your flat roof and prevent costly damage throughout the winter season.

Understanding the Unique Challenge of Snow on Flat Roofs

The Weight Factor

Snow accumulation – particularly wet snow – exerts significant weight on a flat roof. Unlike rain that runs off, snow can build up and stress the roofing structure. This pressure can expose or aggravate existing vulnerabilities, leading to leaks.

Melting and Refreezing

Temperature fluctuations can cause snow to melt and refreeze. This cycle creates roof ice dams that obstruct proper drainage, potentially forcing water to seep through seams or cracks, a scenario less likely with rain.

Insulation and Condensation Issues

Flat roofs may have varying insulation quality. Poor insulation leads to heat escaping, melting snow unevenly. This can exacerbate leak risks, especially if condensation forms beneath the roofing membrane.

Signs Your Flat Roof May be Susceptible to Leaks Caused by Snow

  • Ponding on the roof
  • Sagging or uneven roof areas
  • Cracks, blisters, or bubbles in the roofing membrane
  • Damaged flashing around roof penetrations
  • Ice dams along roof edges
  • Clogged or damaged drains and gutters
  • Stains or water marks on interior ceilings or walls are signs of previous water damage
  • Insufficient or uneven insulation can lead to uneven roof temperatures

GSM Roofing’s Solution-Oriented Approach to Prevention

Regular Maintenance Checks

Our experienced team at GSM Roofing recommends regular roof inspections to identify and rectify potential weak spots. Commercial roof maintenance is key in preventing snow-related damage.

Improved Drainage Systems

Ensuring your flat roof has an efficient drainage system can significantly reduce the risk of leaks. This includes keeping gutters and drains clear of debris.

Quality Insulation and Ventilation

Proper insulation and ventilation help maintain a uniform roof temperature, reducing the risk of ice dam formation and condensation-related leaks.

Understanding why flat roofs are more susceptible to leaks during snowfall is crucial for any building owner or manager. At GSM Roofing, we combine our extensive experience with a commitment to safety to provide top-tier roofing solutions, including preventing roof leaks when snow melts.

Contact GSM Roofing for more information about our roof snow removal services and preventive maintenance plans.

Glad to be wrapping up this project, but most of all ..enjoyed working with you and GSM, your company is spot on and customer service is off the charts! Thank you!

Diana Hess Project Manager