The flat roof is a common design feature for commercial buildings, even if the name is a bit misleading. A flat roof is actually a low-slope roof that provides drainage by sloping very slightly. When functioning correctly, the roof will allow water to either drain away or evaporate within 48 hours of any significant rainfall. However, if the slope of the commercial roof fails, pools of water can accumulate and weigh down on insulation, increasing the puddle’s size until ponding occurs. If your commercial roof is not dry within 48 hours of a rain event, you have an issue with ponding water that needs attention.

Like most structural issues, ponding is a problem that only grows worse with neglect. When a little water is trapped and sits in a minor depression on the roof, the water weight pushes down, continually enlarging the depressed area. The next storm causes more water to collect, and the pond sizes continue to increase.

What are the Causes of Ponding?

Your flat commercial roof may be experiencing ponding for several reasons:

Internal drains or parapet scuppers have become clogged with debris
Roof leaks are forming
Vegetation is growing on the roof’s surface
Workers on the roof walking on the surface and depressing insulation (to service A/C, for instance)
A weakened underlying roof deck
All of these issues can be identified during routine maintenance and repairs by a professional roofing contractor. (Read more about the importance of regular commercial roof maintenance here.)

Resolving Your Ponding Issues

Understanding what causes flat roof ponding is just the first step – knowing how to fix the issue before a new roof is necessary is the goal. A professional roofing contractor will:
- Document and track the extent of the ponding
- Make sure drains flow freely, especially during severe rain events
- Build up low spots on the flat roof
- Measure and recalibrate your roof’s slope to restore proper drainage across the field
The good news is, fixing your roof could be a lot easier than you think. Remedies can range from small low-slope roof repair to a full tear-off and new insulation installation – but spray foams and roof coatings may prove to be excellent alternatives.

How Can Spray Foam Resolve the Issue?

When tear-off and re-roofing are required, the situation can become challenging in many ways – from the cost of the project to the environmental impact. In fact, when an old existing roof must be torn off and disposed of, it often ends up in the landfill.

Depending on the location and function of your commercial building, a re-roof may disrupt road traffic, require the closing of parking lots, and cause major disruption to tenants or residents below. However, if the flat roof hasn’t suffered severe damage from ponding water, property owners may have the option of forgoing a new roof and applying spray foam and roof coating to restore the roof. These methods are significantly less expensive than a conventional tear-off and replacement while also requiring a smaller crew and less disruption to everyday business. Not to mention, removing a roof when there is a potential for more rain is problematic for everyone.

If the ponding water problem areas on the roof have not become too large, roofers may locally apply the spray foam only as necessary to raise the depressed areas and build an adequate slope to the roof. This is why it is essential for property owners to arrange for routine roof inspections. While small ponding problems can be fixed with spray foam and roof coatings, a more severely damaged (or saturated ) roof may require a much more extensive fix.

If you are responsible for the maintenance of a commercial roof, whether at a shopping center or condominium, call the roofing experts at Unicoat Industrial Roofing today to arrange an inspection. With over 4,000,000 gallons of roof coating applied in the last 20+ years, careful attention to detail, and customer-driven service, we have the deliver the expertise and roofing solutions you need.