Roof guide
Pitched roof guide
Pitched roofs need the pitch angle because the slope area is larger than the plan area. The calculator uses that factor automatically.
Pitch matters
The steeper the roof, the more the actual area grows compared with the plan area.
Keep the units simple
Use meters for length and width, degrees for pitch, and percent for waste.
Watch the ridge and eaves
Cuts at the ridge and eaves are the usual source of extra material use.
Example
Pitched roof sample
12 m x 8 m roof with 30 degrees pitch and 12 percent waste.
Slope factor increases the area to 110.9 m2, and waste brings the ordering estimate to 124.2 m2.