Measuring your roof correctly is the difference between a smooth metal roofing project and expensive surprises. Start by sketching each roof plane (each flat “face” of the roof) and label ridges, hips, valleys, eaves, rakes, and penetrations.
Measure each roof plane:
For every plane, measure the eave length (horizontal bottom edge) and the slope length (from eave to ridge along the roof surface). Multiply to get the square footage for that plane, then add all planes together for total roof area. If you can’t safely measure on the roof, measure from the ground and confirm with aerial imagery, but field measurements are best.
Calculate panel quantity:
Panels are ordered by coverage width (after side-lap) and panel length (slope length plus overhang). Divide each eave length by the panel coverage to get the number of panels per plane, then round up. Panel length typically includes the eave overhang and accounts for ridge trim/closures—follow your manufacturer’s detail.
Add trim takeoffs:
- Eave/drip edge: total eave footage
- Rake/gable trim: total rake footage
- Ridge cap: total ridge footage
- Valley metal: total valley footage
- Sidewall/endwall flashing: measure where the roof meets the walls
Accessories and extras:
Count pipe boots, skylight/chimney flashing kits, closures (inside/outside), fasteners, butyl tape, and sealant. Add waste: commonly 5–10% for simple roofs, 10–15% for cut-up/valley-heavy roofs.
Before ordering, double-check units (feet vs inches), panel profile, and that trim pieces match the system—accuracy here saves the most money.
In summary, an accurate metal roofing order comes from breaking the roof into simple planes, measuring eaves and slope lengths carefully, and then converting those numbers into panel counts based on true coverage width—not just overall panel size. When you also total every trim run (eave, rake, ridge, valleys, and wall flashings), count penetrations and closures, and include a realistic waste factor, you avoid mid-job delays, extra delivery fees, and leftover material that doesn’t match.
