How to prevent ponding water on a roof area
- by Dina Vaisman
- Oct 17, 2025
- Roofing Questions
Ponding water can damage the structure of a flat roofing system. It is important to take measures to prevent this, as it can cause issues, including health and safety hazards.
In this article, we will discuss:
- Introduction to ponding water on a roof area
- What issues can ponding on a roof area cause?
- How can you prevent ponding?
- Wonderbuilds Cut to Falls Waterproofing System
Introduction to ponding water on a roof area
Ponding water is water that ends up being collected on a surface after rain and does not drain away within a reasonable time.
Flat roofs are likely to retain ponding water. This can sometimes be caused by the laps and how thick the waterproofing membranes are, or the metal trims. A small amount of ponding water on the roof area will not usually cause significant issues. The damage caused by ponding will depend on a few things, how much water there is, how much area the water is covering, how often, and if the roofing materials used are good quality. Installation also plays a part in how badly ponding will affect the roof area. The amount of foot traffic on the roof can also determine how much of an issue ponding will be.
What issues can ponding on a roof area cause?
If the waterproofing membrane has not been installed properly, or is not able to withstand collected water, ponding water could eventually penetrate the roof system. Additionally, deflection could occur because of the extra weight of standing water.
Ponding on the roof could be affected by silt, which can be a safety hazard, and is not pleasant to look at. In winter months, ponding water can become ice, making it very difficult to walk on.
How can you prevent ponding?
Designers should follow guidelines and design the roof to ensure it has a gradient of 1:40. If a membrane is single ply, this gradient should be enough to drain the roof seeing as there would not be a lot of lap joint build-ups.
Wonderbuilds Cut to Falls Waterproofing System
A cost-effective solution is the Wonderbuilds Cut to Falls Waterproofing System. This is an effective method to prevent potential ponding on a roof area. With this system, standing water would be directed towards internal and external gutters, or internal outlets, which would enable free flow of water from the roof area. The Wonderbuilds system can be used on refurbished or new build projects. Our technical team can offer specification, design, and delivery. If you would like any further information, please do not hesitate to contact us on admin@wonderbuilds.co.uk
FAQs
- Water that remains on a roof after it has been raining.
- The water could penetrate the roof system or cause deflection. It is also a safety hazard as it can cause the surface to be slippery.
- By ensuring that the roof has the correct gradient level and installing a cut to falls waterproofing system.
- Contact Wonderbuilds at admin@wonderbuilds.co.uk
Quick summary
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