One of the biggest concerns of homeowners regarding flat roofing is that it may hold water that could lead to eventual leaks. However, that’s not the case. A properly-built and maintained flat roof will never hold water for a long time, utilizing effective drainage and gravity to let the water slide right off while the rest dries on top. Whether you’re a curious reader or a concerned homeowner, this blog is here to ease your mind, dispelling rumors that flat roofs and ponding water mean immediate leaks.
Flat Roofs & Ponding Water: Why It Doesn’t Lead To Leaks
Let’s say you’re reading this through a raging thunderstorm outside, wondering if your home’s roof is going to survive the downpour. The truth is, flat roofs are designed to drain most of the water that accumulates during rain showers, but ponding water only becomes an issue after 48 hours.
Here is a look at why flat roofs won’t leak.
- Appropriate Roof Pitch
Despite their names, flat roofs aren’t actually completely flat. They have a slight pitch of about 140 to 180 or 1:4 inches per foot. This means that any rainwater or melting snow won’t just stick around and pond on top of your roof forever. The slight pitch will gently let all the water slide right off, keeping your roof safe from ponding, mold, and other forms of damage.
- Effective Drainage
Next, the pitch combines with a strategically installed drainage system to prevent pooling water. The water slides into small openings at the edge of the roofs called scuppers, through which it enters the drains. Through the drains, it eventually goes into the gutters, leaving your roof safe from any potential leaks.
- Quality water-resistant membranes
Most flat roofs are coated in a special waterproof membrane, designed to repel water. These act as a barrier between the moisture and the roofing material underneath, so that even if some water manages to linger for a few hours or even a day or two, it won’t actually corrode the roofing material before it eventually evaporates.
Flat Roofs & Prolonged Ponding: Why It May Happen
As previously established, a properly installed and maintained flat roof won’t hold water. however, there can be instances when the water doesn’t drain effectively. From clogged drains to sagging roofs and more, here is a list of reasons why your roof may be holding water.
Read along to find out.
- Blocked Drains
One of the main reasons why water may be unable to slide off your flat roof is because of a clogged drainage system. Over time, your drains can have leaves, twigs, or other forms of debris enter and create blockages. Meaning? If rainwater tries to leave the roof, it doesn’t have anywhere to go. This leads to ponding, moisture damage, and eventual leakage.
- Shabby Roof Installation
If you regularly clean your drains and are sure there are no obstructions, but still find ponding water, the next reason could be poor installation. Flat roofs require precise calculations to create the ideal slope. If the roofers made an error or simply weren’t experienced enough, they may not have created enough pitch or might have added dips and bumps that could be preventing the water from draining.
- Age & Structural Damage
Think about it. Is your roof old? Over the decades, your roofs can settle and sag, leading to ponding water and inefficient drainage. This could lead to material corrosion and eventual leaks. If that’s the case, you should probably invest in some roof repair or maintenance services immediately.
Conclusion
To conclude, flat roofs are never completely flat and, therefore, don’t “hold” water. They have a slight pitch that allows any rainwater or melting snow to slide right off. Not to mention their smartly designed drainage systems that prevent long-term ponding. If you find that your roof is holding on to ponding water for over two days, it’s an indicator that something’s wrong with the drains, structure, or installation. We hope this blog helped you understand flat roofs a little bit better. If you have any more questions, please drop us a line and we’d be happy to answer them!
FAQs
How many drains should a flat roof have?
Any kind of roof should have at least two drains to ensure proper drainage.
What is a flat roof drain called?
The specific drain found on flat roofs is known as a scupper drain.
What is the maximum distance between roof drains?
According to experts, the maximum distance between roof drains is 200 ft, though this may vary depending on the size and design of the roof.