Standing Water on Flat Roof

If you are a homeowner or business owner with a property sporting a flat roof, you have probably been noticing some problems that aren’t quite common as when you have a sloped or gable roof. A common issue with flat roofs is that water tends to form ponds or puddles due to the inability of water to naturally drain away from the flat roof with just the aid of gravity. Instead, flat roofs rely heavily on the installed gutter system. So, if you own, or manage, a building with a flat roof, you may have noticed an issue with ponding water.

Unfortunately, aside from having problems with the gutter system, there is also the chance that the thing causing standing water on the flat roof is the design of the roof itself. Flat roofs have a low slope but are not completely flat, which is why water still flows into the gutters. When a flat roof is not designed properly, then water tends to stand in lower end areas. Usually, these are the points where water collects and where most roofers put in an efficient drainage system. However, when the drainage and gutter system are not installed effectively, water will end up ponding every time there is rain or snow.

What is Standing Water?

Standing or ponding water is a common thing when it comes to flat roofs. Right after a storm or when the snow starts to melt, you’ll likely find water on your flat roof. However, this is not a problem until the water does not drain or evaporate after 48 hours. When you still find water on your flat roof after a few days, then you definitely need to get your roof assessed because while this may not seem like a huge issue, the problems that ponding water can cause can be very costly.

Ponding water can cause many long, and short-term effects. So, here a few things that you should know to protect the large investment that is your flat roof.

Common Reasons for Standing Water on Flat Roof

While it may be difficult to identify the main cause of ponding water from the start, there are some common reasons which you should consider. When you see ponding water, however, the best thing to do is to contact your local roofing company and get a thorough assessment to identify the cause and then implement the right solutions to fix and prevent the same thing from happening in the future.

If you don’t regularly maintain your roof gutters, leaves, sticks, and other random debris tends to pile up on these gutters and cause a blockage which prevents water from draining efficiently.

When there is too much roofing material along the edges of a flat roof, the excess material may end up blocking water from draining into the gutters even when the gutters aren’t blocked.

Improperly installed roof flashing can also be another cause.

Damage caused by Standing Water on Flat Roof

Finding water on the top of your flat roof may not seem like a big deal. While it isn’t a cause for immediate alarm, it is still something that needs to be repaired and fixed up sooner rather than later. Given time, standing water can cause other major problems to your roof. Some of this includes the problems listed below.

Standing water can magnify the effect of harmful UV rays which can cause damage to your roof. With the ponding water, this damage is sped up.

Ponding water can add more weight to the area where the water collects. This puts extra pressure on this area, causing it to sag and get deeper, making it even more prone to collecting water. Aside from compounding the problem, the added weight can also damage the underlying structure.

On the areas where water collects, algae and moss tend to grow. This fungal and organic growth can affect other areas of the roof and even seep into the underlying structure.

When any of the above happens and as your roofing membrane is weakened and roofing leaks begin, the structural integrity of your flat roof may become compromised. This results in many risks, including a full or partial collapse.

Now that you are aware of the many risks of ponding water on your flat roof, it is essential to take the necessary steps to rectifying the issue to ensure no further damage is caused.

Is Standing Water on a Flat Roof a Problem?

When water starts to stand on your roof, not only does it lead to leaking and other damages to your property, it also reduces your roof’s lifespan and negatively impacts its structure. In the roofing industry, ponding water refers to water that has stood flat on your roof for longer than 2 days following rain.

Standing water on a flat roof is also known as ponding which is a term that describes how the water collects in pools on certain surfaces of the roof, thus forming ponds. This typically happens right after a heavy downpour. However, most pools either drain off the roof or evaporate. When the water is stuck on your roof for prolonged periods of time, typically more than 48 hours, then it should be something that needs to be dealt with.

If it lasts for much longer, contacting a professional roofing team would be the best option in order to avoid further damage to your property.

It is also essential to note that ponding is not typically an imminent threat, as roof membranes are composed of water-resistant materials. Although immediate leakage is not likely to occur, recurring ponding can cause damage to the roof.

But the best thing to do is to keep your roof in tip-top shape to avoid major damages and to also keep it at optimum performance levels. That is also the best way to get the most out of your roof over the years.

Is standing water on a flat roof a problem?
Yes, it is.

The next question you should now be asking is “how do i fix this problem?”

In order to find a solution, every homeowner should first identify the reason why their flat roof is holding water.

Reason 1 – Inadequate or Obstructed Roof Drainage Systems

One of the most common reasons why a flat roof tends to hold standing water is due to the fact that there is an ineffective drainage system. When the drainage system of your roof is inadequate or obstructed, this will tend to keep the water on the roof, especially since there is no roof slope to naturally drain the water away with the aid of gravity.

While this might seem like a major problem that will require an entire roof replacement to solve, this is actually one of the easier reasons to correct. One of the major fixes is to implement regular roof maintenance. There are 3 different ways that flat roofs drain. The first is through the roof scuppers which are collector heads leading to downspouts. The second is through sloping towards a gutter system that guides the water away from the roof. The third is through roof drains.

By maintaining roof drains and gutter systems clean, water should flow out and avoid ponding.

Reason 2 – Roofing Structure, Design, and Deflection.

Another reason that can cause ponding water on your flat roof is because of the form of the roof itself. This is trickier to fix because regular roof maintenance will no longer be able to cut it. When a roof is designed poorly, ponding water can be due to the structure or by parts of the roof that start to sag under pressure.

This issue can also be because of improper placement of roof gutters and drains, which can lead to these drainage systems to be inefficient even when clear and unobstructed. If the structure that the flat roof is installed upon has settled or sagged, ponding water will be equal to the distance that the structure has deflected below the roof gutters or scuppers.

Reason 3 – Compressed or Saturated Roof Insulation

The third reason which is a common cause for ponding water is due to compressed or smashed roofing insulation layers. This can occur due to the added weight of construction materials, HVAC equipment, or other heavy equipment placed on top of a flat roof. Over time, roof insulation may have also degraded and become saturated.

Most flat roofing insulation systems tend to be quite sensitive to water and degrade rapidly or even dissolve when exposed to water or other liquids. When the insulation layer starts to degrade or dissolve, it loses its shape and forms an indentation on your roof where water can form ponds. This will then cause an even bigger problem since the standing water can cause more damage to the roof and the underlying insulation, thus making the indentation grow deeper, increasing the area where water is collecting. The best way to fix this is to replace the roofing insulation layer.

Determining the major causes of standing water on your flat roof can be a difficult task. However, there are experts in your area readily available to give you a hand and recommend the best course of action.

Tag Archive for: water ponding

Standing Water on Flat Roof

Standing Water on Flat Roof

What is Standing Water?

Common Reasons for Standing Water on Flat Roof

Damage caused by Standing Water on Flat Roof

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