Why Poor Drainage on Your Commercial Roof is a Problem
Standing water is fairly common. But if you’ve ever wondered how to know when a little water is a big problem, this information may help.
What causes it?
“The primary source of ponding water is lack of roof slope in the system,” says Brent Taylor, Senior Vice President and Chief Business Development Officer, D. C. Taylor Co., Cedar Rapids, IA. The absence of roof slope isn’t the only poor design decision that results in drainage problems; others include:
- A scupper or drainage system that has no crickets or saddles.
- A curb that obstructs the drainage path.
- An inadequate drain sump.
- Clogged drains and gutters.
Deck deflection is another possibility. If there’s been a leak that caused the deck to corrode or insulation to compress, the deck or insulation might sag enabling water to collect. Another source of this deflection is the weight of rooftop equipment.
Why is it a problem?
Water that doesn’t drain from the roof properly provides an opportunity for microbial growth. It also accelerates deterioration. “Manufacturer requirements state that water should not stand on the roof for 48-72 hours because it reacts with the membranes and causes premature aging,” says Bob Ford, Regional Account Manager, D. C. Taylor Co., Cedar Rapids, IA.
It also creates slip and fall hazards for rooftop workers, added weight to the roof that the structural members may not be designed to hold, and can lead to severe leaks.