If you’re a roofing contractor, building owner, or other person responsible for the maintenance of a building, chances are you’ve experienced the hassles associated with ponding water. Areas on flat rooftops where the roof is sunken are susceptible to leaks, corrosion of the roof membrane, deck/structural damage, mold, insect problems, and other hazards that signal poor flat roof water drainage. (See: The Effects of Ponding Water) These low areas are not uncommon on new and old flat rooftops. Most of the time they’re not even a result of improper of installation; It’s just a part of the natural process.
Here’s three of the most common causes of water ponding:
Settling of a Building’s Foundation
Just as old homes settle into their foundation and make you feel like you’re in a scary movie every time you hear a creak, so do large large buildings and their rooftops. It’s just a part of the natural process and usually doesn’t do too much harm. As a building’s concrete foundation settles, the rooftop has a tendency to sag, creating these low areas for water to pool.
As winter and summer come and pass each year, the soil underneath the foundation of the building freezes and thaws affecting the building’s foundation. This can cause the roof deck to sink in like a bowl and collect water on large buildings with flat rooftops. As more and more water ponds over time, the weight of the water causes changes in the overall structure of the roof deck, further contributing to the sagging and worsening the problem.
Wet or Compacted Roof Insulation
When a building’s roof insulation is exposed to water from a leak, the insulation becomes heavy and can cause the roof to sag in these areas. In the same way, HVAC units and other heavy equipment can compress the insulation and create low spots that further exacerbate these water ponding areas.
Ponding water is one of the most common problems commercial roofers face. And the longer you wait to deal with it, the more complex and expensive the repairs become. If you’ve got a small ponding area and you want to avoid expensive repairs down the road, our product GreenSlope can help. If you’ve got a larger, deeper area and you’re not quite sure if a roof leveling compound will be enough or which option is best, feel free to contact us with any photos, project specs, etc. and we’ll be happy to give you a free consultation. Our team has over 30 years of experience in commercial roofing – and believe me, when it comes to ponding water, we’ve tried all kinds of hacks and now know what works.