Prevent Water Accumulation on Your Flat Roof - Essential Tips for Effective Drainage


Flat roofs are a popular choice for many buildings, but they come with their own set of challenges. Water accumulation is a common problem for flat roofs, mainly because they do not drain water as effectively as other types of roofing.

In this blog, we discuss why effective drainage is crucial for flat roofs, as well as dig into the common causes of water accumulation and the proper maintenance to keep your flat roof - and your property - safe and healthy for years to come.

Understanding Flat Roof Drainage Systems

Efficient drainage is absolutely essential for flat roofs to prevent water pooling. Without it, your building is at serious risk for structural problems. The point of a drainage system is to guide water quickly away from the roof into the gutter system - this protects your building from the inside out.

When a flat roof has a well-designed drainage system, it offers some key benefits:

  • Prevention of ponding water, which can add dangerous weight and lead to structural damage, leaks, and roof deterioration.
  • Extension of the roof’s lifespan by keeping water from lingering where it shouldn’t.
  • Reduction of the risk of water leaks that lead to structural damage, mold, and other extensive water damage.
  • Preservation of the overall integrity of the roofing materials and building itself by properly managing runoff.

Types of Flat Roof Drainage

Flat roofs can be sleek and modern, but they do require a little extra care when it comes to drainage. The shape of the roof itself plays a big role: there should be a slight slope to the roof to facilitate water runoff. If the roof isn’t designed correctly or has settled since its construction, ponding can become problematic. In these cases, corrections can be made (and are necessary!) to improve drainage.

Beyond the roof’s shape, flat roof drainage often includes:

  • Scuppers: openings at the lowest points of a flat roof that channel water into downspouts and gutters
  • Overflow drains: secondary drains that handle heavy rainfall or snow melt by directing it to a specific area; sometimes connected to plumbing or underground drainage
  • Roof cricks (saddles): triangular structures built onto the roof around chimneys or vents to divert water away from trouble spots
  • Gutters: traditional gutters around the roof edges collect runoff and funnel it into downspouts; most common when a flat roof is part of a larger building with sloped roofing already in place elsewhere

Signs of Ineffective Drainage

There are several things to watch out for to know if your flat roof’s drainage system isn’t up to par. Look for issues like standing water (ponding), algae growth, or ice dams forming around the roof perimeter. Check your drains and gutters, as clogs and obstructions can increase the risk of water accumulation. If you see any debris, like leaves or branches, make sure to clear it away immediately to improve proper water flow.

You can also inspect your roofing materials for cracks, punctures, or deteriorated seams in the membranes. Any of these issues can allow even the smallest amount of water to penetrate and accumulate - wreaking havoc on your roof and the integrity of the building.


Tips for Improving Flat Roof Drainage

To keep water flowing correctly and prevent accumulation, consider these tactics:

  • Install a comprehensive drainage system, or upgrade the one you have. This includes gutters, downspouts, and internal drains.
  • Ask a professional to inspect your roof for proper slope to facilitate smooth runoff.
  • Keep all drains and gutters clear of debris to avoid clogging.
  • Quickly repair any defects (cracks, holes, or seam issues) in the roofing materials

Regular Maintenance is Key

To prevent water accumulation, maintaining your flat roof is crucial. Other than keeping your gutters clear, you also need to inspect the surface of your roof. Remove any leaves or branches that may clutter up the surface to ensure water can flow where it needs to. While you’re at it, you can trim back any trees or nearby plants that could interfere with the drainage system.

At least twice a year and after severe weather, schedule regular roof inspections to identify and address any drainage issues or damage. This is also a great opportunity to check for signs of ponding: puddles of water, algae growth, or water stains.

When To Get Professional Help

If you find yourself dealing with persistent drainage issues or have noticed clear signs of trouble, it’s time to call an expert. A qualified roofing professional can inspect your roof, diagnose the root cause, and recommend solutions specific to your flat roofing system and building structure.

Proper drainage truly is the backbone of a healthy flat roof. By understanding the importance of drainage, knowing the signs of common issues, and staying on top of maintenance, you can protect your building from the damage of water accumulation. Your flat roof can stand tall for years to come with the right approach.