How it works
Sloped roof area = plan area × √(1 + (rise/12)²); sheets = ceiling(area × waste allowance ÷ sheet coverage).
Input definitions
- Roof plan length (ft)
- Enter the value in the labeled unit.
- Roof plan width (ft)
- Enter the value in the labeled unit.
- Pitch rise per 12 run
- Enter the value in the labeled unit.
- Coverage per sheet (ft²)
- Enter the value in the labeled unit.
- Waste allowance (%)
- Enter the value in the labeled unit.
A worked example
- Roof plan length (ft)
- 40
- Roof plan width (ft)
- 24
- Pitch rise per 12 run
- 6
- Coverage per sheet (ft²)
- 32
- Waste allowance (%)
- 10
Assumptions & limits
Uses only the values entered. Rates are illustrative inputs, not live quotes, legal rules or personalised advice. Check provider terms, local requirements and measurements before acting.
Sources & review
Maintained by AnsRio. Methods and examples use automated checks; this does not imply independent professional certification.
Method updated 2026-10-19. Content checked against the stated method and examples. Our verification approach.
Report an issue with this tool or suggest an improvement ↗
Common questions
Does plan width include all roof sections?
Enter the total horizontal footprint covered by the roof. Dormers, valleys, overhangs and separate wings need added measurements.
How does Roof sheathing sheet count calculate the result?
Sloped roof area = plan area × √(1 + (rise/12)²); sheets = ceiling(area × waste allowance ÷ sheet coverage).
What should I verify before using Roof sheathing sheet count?
Uses only the values entered. Rates are illustrative inputs, not live quotes, legal rules or personalised advice. Check provider terms, local requirements and measurements before acting.