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Ponding Water On Flat Roof Solution

Buildings or homes that have a flat roof give property owners one common dilemma: ponding.

Ponding occurs when water tends to stand or gather around a specific portion of the roofing system, creating a puddle or a “pond.” This doesn’t occur often on pitched roofs because the natural slope of a pitched roof allows the water to drain off naturally. However, when pitched roofs have clogged gutters or sagging slopes, there is also a tendency for ponding to occur.


On flat roofs, however, ponding is a common problem that many home and commercial building owners face. Since flat roofs often have a poor drainage system, the water can end up staying on top of the property for days, weeks, and even months at a time. Over time, this can cause severe damage on the property since the water can slowly seep into the internal roof structure or also cause the growth of organic biomass, such as mold, moss, and algae. The long term effects of ponding water are not good, which is why finding a long term solution towards the prevention of water pond formation on your flat roof is important - if not essential if you don’t want your roof to sustain severe damage.

Water puddles on a flat roof will form whenever there is rainfall. While this is to be expected, the puddles should either evaporate or drain away within the next 2 days. If you notice the water puddles staying longer, then that is a sign that there might be a problem on your roof. Even worse would be when an area on your roof where ponds form starts leaking inside - this means that the water has significantly damaged and gone through the roof barrier and into your home.

Main Effects of Water Ponding

The main causes of water ponding include a saggy roof and a clogged drainage system. When your roof starts to form water ponds, you can expect these long term problems to occur eventually.

Make Your Roof Dirtier

With all the debris in the air, some bits of dirt and other items can get caught in the water and start collecting on your roof. If the pond has formed and stayed on top of your property for a while, you can expect it to be a muddy mass of dirt and debris instead of a puddle of clear water. The water starts collecting dirt after a while and if not cleaned up, could add a heavier weight for your roof to support. This can only cause further damage to your property.

Damage Roof’s Exterior Protective Coat

Most roofing materials are coated with an exterior protective layer that functions as a water-barrier and even as a fire or UV protective layer. When water puddles on top of a roofing material, it acts as a corrosive which washes away this protective coat. Thus, the water weakens your roofing system.

Start Organic Growth

Plants, moss, mold, and other green things will start growing when there is moisture and a good source of sunlight. Since your roof is well exposed to the sun, having a puddle on top of your property will start the formation of a tiny ecosystem. The water can contribute to the growth of deep rooted moss and other small plants. What makes this worse is that the roots and other biomass attachments are likely to damage your roofing materials and infiltrate the insides of your roofing deck.

Shorten Your Roof’s Lifespan

Overall, ponding water damages your roof and shortens its lifespan. The only way to ensure that your roof does not suffer as much is to put up long term solutions which are preventive in nature. While it is normal for puddles to form on a flat roof, having a system that allows proper drainage will prevent long term ponding.

How To Prevent Ponding

Actual solutions can vary depending on the style, form, and materials of your roof. While most of the solutions we provide are applicable for most roofing options, it is still best to reach out to a roofing contractor to find which solutions work best for your specific flat roofing system.

Spot and Fix Low Roof Areas

Since flat roofs are not completely flat, you should take advantage of the gentle slope that your roof has to create a natural system of drainage. To optimize this small slope, you need to find and flatten out any low or sagging areas. These are the spots where ponding will happen. An easy way to flatten out these areas is to use roof plaster.

Optimize Drainage Systems

Gutters are essential to flat roofs since many flat roofs only rely on a gutter system for water drainage. If an inefficient gutter system is unable to drain the water away, the water has nowhere else to go except to form ponds on your roof.

Call A Roofer

While fixing water ponding may seem simple, the best way to ensure that your roof is free from puddles is to get the assessment and advice of a skilled roofer so you can easily find where the weak spots and what the necessary preventive measures should be.

Lastly, checking your roofing Thompsons Station TN, especially after a heavy downpour will also help monitor and prevent the formation of long standing water puddles. If you can’t put up any long term solutions, you can manually drain the water away. However, this can be a hassle.

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