Ice Dams on Commercial Flat and Metal Roofs: What They Are, How They Cause Leaks, and What to Do About Them
Winter weather can be especially hard on commercial buildings, and one of the most common — and misunderstood — cold‑weather roofing problems is the ice dam. While ice dams are often associated with residential roofs, they are also a serious risk for commercial flat roofs and metal roofing systems. When ice dams form, they can lead to roof leaks, interior water damage, and long‑term deterioration of the roofing system.
If you’re dealing with snow buildup, ice, or unexplained winter roof leaks, understanding ice dams is a critical first step toward protecting your building.
What Is an Ice Dam?
An ice dam is a buildup of ice that prevents melting snow and water from draining properly off a roof. On commercial buildings, ice dams most commonly form:
Around roof drains and scuppers
Along parapet walls and roof edges
At transitions between roof levels
Near areas with heat loss below the roof deck
When drainage is blocked by ice, water has nowhere to go. It begins to pond on the roof surface, where it can work its way beneath roofing membranes, seams, and flashing details.
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How Ice Dams Form on Commercial Flat Roofs
Ice dams form when there is an imbalance between roof temperature and outdoor conditions. The process typically looks like this:
Snow accumulates on the roof during winter storms
Heat escaping from the building warms parts of the roof deck
Snow melts in warmer areas
Meltwater flows toward colder sections of the roof
Water refreezes and builds up into ice, blocking drainage
Because flat and low‑slope roofs rely on internal drains and controlled water flow, even a small amount of ice buildup can create significant drainage problems. Once drains freeze, water begins to pond — increasing the risk of leaks and structural stress.
Ice Dams on Commercial Metal Roofs
Metal roofs are often chosen for commercial buildings because they shed snow more easily than flat roofing systems. However, ice dams can still form on metal roofs under certain conditions, especially when:
Snow slides and refreezes at roof edges
Heat escapes unevenly from the building
Gutters or snow retention systems trap melting snow
When ice dams develop on metal roofs, they can force water back up under panels and fasteners, leading to leaks that are difficult to trace and repair during winter months.
Why Ice Dams Are a Serious Problem for Commercial Buildings
Ice dams are more than a surface issue — they can affect multiple parts of a commercial roofing system and the building below.
Roof Leaks and Water Intrusion
Standing water caused by ice dams can penetrate seams, flashing, and aging roof membranes, leading to active leaks inside the building.
Damage to Insulation and Roofing Materials
Repeated freeze‑thaw cycles degrade roofing materials over time. Water trapped beneath the roof surface can saturate insulation, reducing energy efficiency and accelerating roof failure.
Interior Damage and Business Disruption
Water intrusion can damage ceilings, walls, inventory, equipment, and electrical systems — often disrupting daily operations during the busiest winter months.
Increased Energy Costs
Ice dam formation is often a sign of poor insulation or air leakage, which allows heat to escape and drives up heating costs throughout the winter.
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How to Prevent Ice Dams on Commercial Roofs
Preventing ice dams requires a proactive approach focused on roof design, maintenance, and building performance.
Maintain Roof Drainage Systems
Keeping roof drains, scuppers, and downspouts clear is one of the most effective ways to prevent ice dams. Pre‑winter inspections and routine maintenance are essential for flat roofs.
Improve Insulation and Air Sealing
Consistent roof temperatures reduce uneven snowmelt. Proper insulation and air sealing limit heat loss from the building and help prevent ice formation.
Ensure Proper Ventilation
Balanced airflow helps regulate roof deck temperatures and minimizes freeze‑thaw cycles that lead to ice buildup.
Address Ponding Water Issues
Areas where water already tends to collect are prime locations for ice dams. These should be corrected before winter whenever possible.
Schedule Professional Snow Removal
Removing excess snow reduces the amount of meltwater available to refreeze. Snow removal should always be handled by trained commercial roofing professionals to avoid membrane damage.
What to Do If You Have Ice Dams or Winter Roof Leaks
If ice dams have already formed or you’re noticing leaks during winter:
Avoid using salt, chemicals, or sharp tools on the roof
Do not attempt DIY ice removal
Contact a commercial roofing professional experienced with winter conditions
Professional ice dam removal methods are designed to clear ice safely without damaging the roofing system. After removal, a roof inspection can identify underlying issues that need to be addressed.
The Importance of Year‑Round Commercial Roof Maintenance
Ice dams are rarely caused by a single factor. They are usually the result of long‑term issues such as aging materials, poor drainage design, insulation problems, or deferred maintenance.
A comprehensive commercial roof maintenance plan helps:
Reduce winter leak risks
Extend roof lifespan
Improve energy efficiency
Prevent costly emergency repairs
Final Thoughts
Ice dams pose a serious threat to commercial flat roofs and metal roofing systems, especially in regions that experience heavy snow and freezing temperatures. Understanding how ice dams form, why they cause leaks, and how to prevent them allows building owners and facility managers to take control before winter damage occurs.
If your commercial building has experienced snow buildup, ice‑related leaks, or recurring winter roof issues, addressing ice dam risk should be a top priority — not just during winter, but year‑round.