How do you Drain Water from a Flat Roof?

Feb 26, 2020 in News
How do you Drain Water from a Flat Roof?

There should be no such thing as an entirely flat roof. This is because what we know as ‘flat’ roofing systems have to slope slightly in order to remove rainwater. This slope is designed to either shift water off the building perimeter or to drain it through a guttering system. But what if your flat roof isn’t doing this? What are the best fixes for a roofing solution that’s not draining water?

How can you identify a ‘Ponding’ Roof?

Typically, if there is still standing water left on the top of your property 48 hours after rainfall, then your flat roof is what’s called a ponding roof. Frequent muddy patches and unusual algae or vegetation growth are also common signs of this problem.

Why is Ponding Roof an issue?

As it causes the roofing membrane to deteriorate over time, ponding can lead to problems such as: 

  • Reduced material lifespan
  • Regular leakage
  • Loose debris
  • Insulation trouble
  • Potential bug infestation

What are the best fixes for a Flat Roof?

Whilst all of these options will help improve drainage, the most effective fix will depend on what you think is creating the ponding issue, to begin with. Thus, for each of the most frequent causes of a ponding roof, we’ve considered the best solutions:

Problem 1: Inadequate Design. Solution: Internal Drains

Solution: The flat roof itself might’ve actually been made too level, meaning water can’t run off the side. If this is the case, then the easiest fix is to fit an internal drainage system. These are located in the central points of the roof, and transport rainwater underneath the membrane to a nearby sewer. They’re extremely effective as they can be placed anywhere, but they also require regular maintenance.

Problem 2: Inward Sagging. Solution: Roof Levelling Compounds

Solution: The middle of the roof could be facing issues dealing with the weight of rainwater. Again, internal drains can be a good remedy for this, but the most appropriate solution is most likely going to be a roof levelling compound. Products like this help bring up the roof surface in sagging areas and can be used to direct water to a given drainage system

Problem 3: Issues with the Drains. Solution: Gutters, Downspouts, Scuppers

Solution: This could be either blocked guttering or simply an issue of not including enough drains in the flat roof design. In this case, gutters, downspouts, and scuppers can all be added to improve the drainage. All of these are easy to install, and basic instructions for fitting a new drainage system can be here.

In all, having the most effective drainage will help to guarantee a long lifecycle for your flat roof. Moreover, a flat roof with a high-quality design is far less likely to face standing water problems, and this is where RubberBond comes in. You can check out our Product Page to see how exactly we prevent drainage issues. Alternatively, for more information on fixing a ponding roof, feel free to Contact Us.