Estimate a siding job in squares including waste factors

Steps

1. Measure each exterior wall's length and height to calculate gross wall area
2. Subtract the area of windows, doors, and other openings to get net wall area
3. Add a waste factor appropriate to the material (vinyl typically lower, fiber-cement and engineered wood typically higher, shake/shingle highest) and adjust upward for complex rooflines, many corners, or large gable ends
4. Divide the adjusted total square footage by 100 to convert to siding squares
5. Round up to the next full square when ordering, since partial squares are not sold in retail packs