Every roof needs positive drainage which means water should flow off the roof within 48 hours.
Ponding water on roof.
The asphalt roofing manufacturers association is joined by many reputable organizations such as the national roofing contractors association the midwest.
Ponding or standing water is where the water collects on the roof and has not drained within a couple of days.
Most pools of water will quickly drain off or even evaporate but owners should be aware of the signs that ponding has become an issue.
When water pools for longer periods of time it can indicate a serious problem.
Ponding water is known in the roofing community as water that stands in a puddle on the roof for more than 48 hours at a time.
Ponding water is defined as water which remains on a roof 48 hours or longer.
Degrading the roofing material itself.
Deformation of the deck structure.
It may also void your warranty.
However excessive ponding threatens your roof.
Ponding occurs when after a storm or heavy rain water collects in pools on the roof.
Roofs should be constructed in such a way that all water drains within 48 hours of the rain stopping.
Collecting dark colored.
If the water does not drain within a 48 hour period it is highly likely that it will stay even longer and there will be a larger amount of water standing.
On a performing flat roof ponding water is not a problem as it will drain or even evaporate away.
So if your flat roof is collecting water that doesn t drain or evaporate within 48 hours you will need to fix it.
This is a particular concern for older built up and modified roofs.
Flat roofs by their very nature will collect some water when it rains.
Determining the root cause of ponding water regardless of the formula roof coatings should never be an excuse to ignore ponding water issues.
It may result from rain melting snow ice or runoff from rooftop equipment.
The ponding or standing water can.
Ice formations develop and move constantly with changes in temperature.
However when your flat roof has uneven areas due to sagging an insufficient slope or drainage issues the ponding water doesn t dissipate.
After any rainfall lands on a flat roof water will begin to pool.
Ponding water might not be an immediate threat but if it is allowed to persist over time that water can begin to wear on the roofing membrane.
Reduce the longevity of the roof increase exposure of the ponding area to damaging ultraviolet rays collect dirt lead to faster deterioration of the roof s coatings and materials encourage growth of vegetation such as moss algae and plants lead to a leaking.
How to fix ponding on a flat roof depends on the cause of the ponding.
The adverse effects of ponding water on roofs can include.
On modern white roofs the water focuses the sunlight that passes through it like a prism.
