Flat Roof Fall Ratio Calculator
Here's a comprehensive table summarizing the key aspects of Flat Roof Fall Ratio:
| Aspect | Details |
|---|---|
| Recommended Minimum Fall | 1:80 (0.72°)13 |
| Design Fall | To achieve 1:80 fall, design for 1:40 (1.44°)13 |
| Importance | Prevents water pooling, increases longevity, reduces risk of leaks, maintains thermal efficiency4 |
| Calculation Method | Fall = Rise / Run, often expressed as 1/4 inch per foot |
| Building Regulations | Part H requires a minimum fall of 1:80, with design to 1:401 |
| British Standards | BS12056, BS6229, BS8217, and BS8218 all emphasize the need for proper falls1 |
| Internal Gutters | Should be designed to the same criteria as the main roof area13 |
| Zero Falls | Only acceptable with certified systems, but a design fall of 1:80 should still be allowed3 |
| Implementation Methods | Tapered insulation systems, structural sloping, liquid membrane solutions4 |
| NHBC Guidance | For tapered insulation, falls should be no less than 1:602 |
This table provides a comprehensive overview of the essential information regarding Flat Roof Fall Ratio. It covers the recommended minimum fall, design considerations, importance, calculation methods, regulatory requirements, and implementation techniques. This information is crucial for ensuring proper drainage, longevity, and efficiency of flat roofing systems.