Why Flat Roof Drainage Matters: Preventing Standing Water Problems

Flat roofs are a popular choice for extensions and commercial buildings, but one of the most common issues they face is standing water after heavy rain. While modern roofing systems (like GRP or EPDM) are fully waterproof, poor drainage can shorten their lifespan if ignored.

1. What Causes Standing Water?

   • Insufficient falls (roof not angled enough for water to run off).

   • Blocked or undersized outlets.

   • Structural sagging over time.

2. Is It Always a Problem?

   • A small amount of water after heavy rain is normal.

   • Persistent puddles that remain for days can lead to premature wear, algae growth, and freeze-thaw damage.

3. How to Prevent It:

   • Ensure correct falls are built into the roof during installation.

   • Use tapered insulation boards.

   • Fit adequate outlets and regularly check them for blockages.

   • Schedule annual maintenance inspections.

4. Professional Solutions:

   • If your roof already holds water, a specialist can install additional outlets or overlay tapered insulation.

   • For older roofs, a replacement system with proper drainage can save money in the long run.

Thinking about a flat roof for your home or worried about standing water on your current one? Contact ShellCo today for expert advice and installation that lasts.