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Ponding water is simply an accumulation of rain and melted snow that sits in small or large puddles on a roof. The National Roofing Contractors Association defines ponding water as water sitting on a roof’s surface more than 48 hours after a precipitation event. It is one of the most common problems seen in commercial roofing.
Severe cases of ponding can sit for days or weeks at a time if it is not manually drained. Roofing repairs are just like any other type of maintenance for your business. Putting off repairs, or being unaware of a problem due to lack of attention, can lead to much larger and more expensive problems down the road.
Roof Design and Ponding Resilience
Commercial roofing materials and design determine ability to withstand ponding water. Many single-ply roofing systems are constructed with the expectation that 80% of water will leave the roof within 48 hours of the most recent rain event. A few small puddles of standing water after the 48-hour mark are accounted for in the original design.
A roof coating system’s ability to withstand water depends on the coating type. Some heavy-duty coatings can tolerate standing water, while others can deteriorate quickly. Asphalt roofs sometimes follow the 80% rule, but it’s best to limit standing water on asphalt as much as possible.
Consequences of Ponding
Unaddressed ponding water can cause a wide range of problems including damaged paint and corroded commercial roofing materials. Internal leaks underneath the roof can damage insulation, indoor ceilings, and products or furniture. Pests, such as mosquitoes and other types of insects, use standing water as breeding ground. These insects can migrate from the roof into the building itself. Any source of mosquitoes increases their local population, which also increases risk of mosquito-borne illnesses.
Roofs with longstanding puddles of water in Fort Worth, TX, can become hosts for
uninvited plants and animals. Dirt and debris carried onto the roof by wind combines with standing water to become a rich habitat for algae, weeds, grasses, and other vegetation. Roots can grow into the roof itself and make their way into structural components of your building in a surprisingly short time.
landing water and vegetation also attract birds. Birds themselves aren’t usually seen as a problem, but their nests can be problematic. Nests can clog drains, and nests built inside structures can become a source of excrement, fleas, and mites.
Long term ponding water problems may indicate a problem with the original roof. Roof design and pitch should take drainage into account and ensure proper sloping. Most flat roofs aren’t actually flat. They’re designed with subtle slopes to drain excess water. Older roofs can develop unintended low points after years of exposure to direct sunlight and precipitation. Water and melting snow collect in low points and cause structural damage if the problem isn’t addressed.
The weight of the water puts additional stress on roofs and weight-bearing structures. Roof discoloration occurs in a surprisingly short time. Sudden cold snaps that turn standing water into ice cause damage to the roof and underlying structures. Water may actually speed up aging and deterioration because water intensifies UV-rays, especially on white or asphalt roofs.
Sometimes relatively simple roofing repairs can fix standing water issues. Spray foam can be used to fill and build up low points and create positive drainage. This solution is most likely to work when low areas are fairly small. It may be necessary to replace underlying insulation before spraying if there are signs of deterioration on the roof.
Clogged drain lines are another common cause of ponding. Regular commercial roofing maintenance and drain flushing removes leaves, sticks, dirt, and other types of litter from drain lines. A clogged drain leads to slow water drainage and can eventually block drainage altogether.
If water continues to build up on the roof after drain lines have been cleared, you may need to install additional drainage. Consistent heavy rainfall can be overwhelming for large commercial roofs with only one or two drains. Commercial roofing professionals can evaluate your roof and fix ponding water issues by installing additional drain lines or expanding existing lines.
Sumped insulation is a possibility if interior plumbing is involved. A new drain with sumped insulation is installed at a slightly lower height than the roof itself. Water flows downwards to the drain and into an interior plumbing pipe to be safely carried away. Scupper boxes are a useful aspect of commercial roofing repair if ponding water occurs near a building’s edge. Most scupper installations include a new scupper box, downspout, and some type of sumped insulation to create a slight slope.
Sometimes roofing crickets are a good solution. A roofing cricket is a small structure designed to divert and guide water around obstructions. Common obstructions include vents, HVAC pipes, and other structures necessary for your business.
A tapered roof system can also be very beneficial. Tapered insulation adds a slight pitch to the roof. The main disadvantage of tapering is cost and time required for installation. Some tapered roofs have to be installed in pieces to work with the building’s structure and integrate other functions, such as HVAC units or outlets.
Following a regular commercial roofing maintenance schedule has benefits beyond roof integrity. Maintenance and repairs extend the roof’s lifetime and prevent damage to internal structures. Replacing a roof is a time and labor-intensive process that often involves closing the business for at least a short time. A business doesn’t make money or keep its customers happy while it’s closed.
Call Longhorn Commercial Roofing in Fort Worth, TX, if you notice ponding water on your roof. Experienced commercial roofing professionals can inspect your roof, suggest and implement repairs, and help you devise an appropriate schedule for regular maintenance.