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

snow on a flat roof

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 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.

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. Regular 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.

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

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Thank you for your fast response. I take full responsibility for the confusion. Bill was patient and very great to work with - I'm very grateful and appreciative of his time and commitment while investigating this leak.

We also look forward to growing a long-lasting partnership with you and the team. We appreciate your revisions. THANK YOU!

Megan Wine Roofing Service Coordinator June 28, 2022