ROOF MEASUREMENT
Roof Pitch and Area Explained
Roof surface area is larger than plan area on a pitched roof, so estimates use slope geometry as well as the building footprint.
SHORT ANSWER
Start with the inputs you can verify
Roof surface area is larger than plan area on a pitched roof, so estimates use slope geometry as well as the building footprint.
What the estimate means
Pitch describes rise over run and can be converted to a slope factor.
Complex roofs should be divided into planes; valleys, hips, dormers, and overhangs change the measured area.
Where estimates go wrong
Do not rely on plan area alone for ordering or safety planning.
Keep the source measurements and assumptions with the result so another person can review or update the estimate later.
A practical workflow
- Measure plan dimensions and overhangs.
- Determine pitch for each roof plane.
- Apply the correct slope factor, sum the planes, and verify against a roof plan or field measurement.