Roof guide
Flat roof guide
Flat roofs are the simplest case for area calculation, but they still need a realistic waste factor and a check on edges and penetrations.
1. Use the plan area
For a flat roof, the roof surface equals the length multiplied by the width.
2. Add waste
Use waste for overlaps, trims, cuts, and service openings.
3. Check the edge details
Perimeter pieces, upstands, and outlets often drive the final ordering quantity.
Example
Flat roof sample
10 m x 6 m flat roof with 8 percent waste.
Base area = 60 m2. Adjusted area = 64.8 m2.