Putting roof drain gratings to the test: Debunking material durability myths

roof drain gratings test

The durability of roof drain leaf gratings is crucial, as a malfunctioning grate can lead to significant damage before any issues are detected on the roof. An impact test of polypropylene and metal roof drain leaf grates reveals that, contrary to common assumptions, polypropylene grates demonstrate superior resilience and durability compared to their metal counterparts. Polypropylene grates maintained structural integrity and functionality after impact, while metal grates experienced significant deformation and damage

When selecting roof drain leaf grates, durability and impact resistance are critical considerations as roof drain leaf grates are regularly subjected to impacts, such as accidental kicks or dropped tools during roof inspections and maintenance. Ensuring grates withstand these impacts without significant damage is crucial to maintaining proper drainage and preventing potential moisture damage.

Traditionally, metal grates have been assumed to be stronger than polypropylene ones. To test this assumption, VILPE conducted an impact comparison between polypropylene and metal roof drain leaf grates. To mimic real-life impact scenarios accurately, we used a pendulum impact test.

Test setup and procedure

We used a pendulum arm measuring 1.7 meters, equipped with a weight of 2.5 kg, generating an impact energy of approximately 42 Joules. This is comparable to a strong human kick.

We tested our polypropylene leaf grates under three different conditions:

  1. Brand new grate at room temperature.
  2. Brand new at freezing temperatures.
  3. 4.5-year-old grate previously installed on a factory roof.

We also tested competitor metal leaf grates under identical conditions.

roof drain gratings test

Results

The polypropylene grates showed excellent resilience across all three conditions. After impact, each grate retained its original shape, remained fully functional, and showed no significant damage or cracking. Even the 4.5-year-old polypropylene grate performed as reliably as the new grates, demonstrating long-term durability.

Conversely, the metal grates exhibited significant vulnerability:

  • One version was severely bent and rendered unusable.
  • Another metal grate detached entirely from its mount upon impact.
  • A third version remained partially usable but suffered notable deformation, compromising its structural integrity.

Implications and analysis

These test results challenge the widespread perception that metal grates are inherently tougher and more durable. The polypropylene grates demonstrated a clear advantage in impact resistance, maintaining functionality and structural integrity after considerable force. Their ability to absorb and dissipate impact energy without permanent deformation proved superior to that of their metal counterparts.

Conclusion

Based on these findings, polypropylene leaf grates offer practical advantages over metal grates in terms of durability and resilience. Roofers, builders, and facility managers should reconsider previous assumptions regarding metal superiority and explore the benefits of high-quality polypropylene alternatives.

For further details on our testing procedures or inquiries about our polypropylene roof drain leaf grates, please reach out—we welcome your interest and are happy to provide additional information.