Measure every elevation, deduct openings consistently, add gables and complex shapes, then convert by the manufacturer's actual coverage—not nominal dimensions.
Take off by elevation
Separate materials, heights, gables, dormers, and access conditions. Photos and marked drawings make the quantities reviewable.
Use published coverage
Panels and cartons may have overlaps, exposure, and piece lengths that change usable coverage. Round to full packages and compatible production lots.
Include water-management details
Price removal, substrate repairs, weather barrier, flashing, penetrations, transitions, trim, sealants, scaffolding, disposal, and protection.