Is there a puddle of water left on your flat roof after a heavy rain shower, and are you wondering if it's harmful? This article explains when you can take action yourself and when it's necessary to call in a professional roofer to prevent damage.
Water on a flat roof: When is it a problem?
It's a common sight: a layer of water on a flat roof after a rain shower. In many cases, this is harmless, especially if the water evaporates or drains away naturally within 24 to 48 hours. However, when puddles persist, it's called water accumulation. This can lead to additional stress on the roof structure and accelerated wear and tear of the roof covering.
For more information about permitted amounts, please also read our article " How much water can remain on a flat roof? " However, if the water is deeper than 5 centimeters or if large areas are flooded, caution is advised.
Take action yourself or call the expert?
Before calling a roofer, you can check a few things yourself. Often, the cause of standing water is simply a clogged drain due to leaves or debris. In that case, you can often solve the problem yourself by clearing the drains. Consult our " Step-by-step plan: Cleaning your gutters and drains yourself ."
However, if you need to remove a large amount of water immediately to prevent leakage or the risk of collapse, a flat-suction submersible pump is the fastest solution. This allows you to pump the roof almost dry without having to wait for a roofer.
Flat suction submersible pump
When is a roofer really necessary?
There are situations where a pump or a cleaning isn't enough. You should call a roofer if you notice the following signs:
- Visible leaks: Damp patches on the ceiling or walls inside the house are a direct sign that the roof covering is no longer waterproof.
- Blistering: Do you see bumps or bubbles in the bitumen? This indicates moisture under the roofing.
- Construction defects: If water consistently remains in the same spot, even after thorough cleaning, there may be an incorrect slope. Read more about this in " Recognizing Construction Defects in a Sloping Flat Roof ."
- Wear and tear: Crumbling edges or cracks in the roofing require professional repair or replacement.
A roofer can perform an inspection and determine whether spot repairs are sufficient or whether a complete roof renovation is necessary. For a structural solution to flooding, you can also consider " Installing a green roof to prevent flooding ."
Prevention is better than cure
To avoid unexpectedly having to call in an expensive roofer for an emergency repair, prevention is essential. Good drainage is half the battle. In situations where the roof consistently retains water due to subsidence, an automatic submersible pump with a sensor can be a solution. It switches on as soon as water is detected.
Submersible pump with water sensor 3mm
Frequently asked questions about water on flat roofs
Is stagnant water on a flat roof always harmful?
Not immediately. A thin layer of water that evaporates within 48 hours is normal. It only becomes harmful if the water remains for an extended period, as this softens the roof covering and places a heavy load on the structure.
What is the average cost of a roof inspection?
A standard roof inspection usually costs between €150 and €250. This is often a good investment to prevent further damage and expensive renovations in the future.
Can I fix a leak in my flat roof myself?
Minor emergency repairs with cold bitumen or repair paste are possible, but these are often temporary solutions. For a durable, waterproof finish, the expertise of a roofer is recommended.
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