Footprint, then pitch, then net coverage
Measure the horizontal building length and width, or a walked roof area if you already have one. Apply rise-per-12 so the sloped surface is not the plan area.
Net coverage is after the rib and the side lap. A 36 in panel that nets 34 in is not a 36 in coverage. Enter the label, not the marketing width.
Trim is not panels
Ridge, hip, eave, gable and closures are linear. Fasteners follow the manufacturer’s pattern. Keep them as extras so a later estimator can change the panel without losing the trim.
Do it in order
- Enter horizontal dimensions and rise per 12.
- Type the selected panel’s net coverage, not the overall width.
- Round up to whole panels, then add trim and fasteners as separate lines.
Worked example — 30 ft × 20 ft, 6:12, 36 ft² net, 10% waste
Plan 600 ft² × 1.118 ≈ 671 ft² sloped. With 10% waste that is 738 ft². At 36 ft² net coverage the order rounds to 21 panels. Trim is still missing from that count on purpose.
Planning boundary
This is a panel-coverage method. It does not design clips, thermal movement, underlayment or a wind rating.
Can I use shingle squares?
Not for the panel order. Squares hide the net coverage of a specific profile.
Does this cut panel lengths?
No. It counts coverage. Shop lengths are a separate takeoff.
Standing seam vs exposed fastener?
Coverage and waste differ. Enter the product you will buy.