Ponding Water on Flat Roof

Flat roofing structures, despite their name, are not completely flat. Instead, these should be more aptly referred to as low-slope roofs since these need a slight slope to allow rainwater to drain into the gutters. 

Standing water begins forming atop a rooftop when there is an inefficient drainage system. This allows rainwater or melted snow to collect and stay on the roof surface for a period of 2 days or even more. On some roofs, conditions may be enough for the water to evaporate and dry up.

To specifically define the terms, ponding or standing water refers to when water has not drained off the roof and has formed puddles or ponds 48 hours following the reason for the water.

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. When ponding water forms atop roofs, this may end up causing long term problems with the worst case scenario being that the roof will have to be replaced. And in cases where a replacement may not be necessary yet, the roof will definitely be in need of major repairs that are likely to be quite costly.

The main cause of standing water on a roof is because the water is unable to drain off property. Here are more specific things that you need to check to identify what the root cause of your ponding water problem is.

  • When the gutters or drains have been blocked by debris such as twigs, leaves, or even random objects.
  • When the pitch of the rood is too low and has not been done correctly, such as having used weak membranes or issues with caulking.
  • When there is too much roofing material on the edge of the roof
  • When the flashing has not been installed correctly

What are the Effects of Ponding Water?

There are several ways by which ponding water can affect your roof. These are listed below.

  • The water on your roof can magnify the effects of sunlight, causing the UV rays to hasten the process of aging and cause damage to the exterior roofing materials.
  • Standing water on a rood promotes biotic growth, such as the growth of algae, and even small plants. This is detrimental to your roof since the roots of these growths can furrow into your roofing material and damage it, particularly in the seams. 
  • During the winter, ponding water that has not been cleared can end up freezing on the roof surface and put pressure on the structure. 

Roofing issues, such as denting and an incorrect slope are some of the major things to check when assessing your roof. These can likely cause ponding water problems. Each of these problems can further be attributed to poor roofing design which is the reason why it is important to careful plan your roof design. Hiring an experienced roofing contractor is a vital part of the roofing process because we are able to guide you through the planning and then finish off the project with excellent workmanship. 

What happens if you ignore Ponding Water on a Flat Roof?

Is your roof having problems with ponding water? While the low slope of a flat roof makes it quite prone to collecting water right after rainfall, most roofs should be able to dry up within the day. If you start to see water on your roof multiple days after, there may be an ongoing problem that you need to address as soon as possible. But if the water is gone in a couple of days, your roof is doing just fine. 

If you decide to ignore ponding water, however, you are likely to experience even more problems in the future. For one, it can cause further damage to your roof, causing leaks, a weakened structure, and more. If not handled, you may even risk your roof caving in on your home from the added weight of the water. Ponding water on a flat roof can be a compounding problem that worsens its own condition by sinking your roof deeper and deeper, causing even more water to collect in that area. Water always looks for the lowest place it can go.

The first step to fixing this problem is to get the help of a roofing contractor to assess the damage and determine the best course of action. The local experts at New Covenant Construction are here to help you to fix any problem with your roofing system.


Related Articles