How do you measure a roof for metal roofing?

1. Panel length

Panels usually run in one piece from eave to ridge. Measure along the slope, not the level run, from the eave edge to the ridge, then add the overhang the panel maker specifies at the eave and subtract any gap it requires at the ridge. On a hip roof, panels on the triangular ends get shorter as you go, so measure in steps.

2. Panel count

Divide the eave length by the panel's net coverage width, which is less than its total width because of the overlapping rib or seam. Exposed-fastener panels often cover about 3 feet; standing seam panels are commonly 12 to 18 inches wide. Round up.

3. Trim

Measure the linear feet of eave, rake, ridge, hip, valley, sidewall, endwall and any pitch change. Trim comes in fixed lengths, often around 10 feet, so allow for overlaps.

4. Pitch

Know the slope, because it sets minimums. The residential code calls for at least 3 in 12 for lapped panels without lap sealant, 1/2 in 12 with applied sealant, and 1/4 in 12 for standing seam, and many manufacturers require more for specific panels.

5. Accessories

Closure strips, screws, clips, butyl tape, sealant, pipe boots and underlayment are ordered from the same measurements.

6. Waste

Simple gables need little extra; hips, valleys and dormers add more cutting waste.

Practical advice

Measuring with an aerial report is safer than climbing. Many suppliers will turn your measurements into a cut list, but have a pro verify them first, since panels cut to length usually cannot be returned. See how roofers measure a roof and metal roofing in Georgia.