Panel Layout, Handling, and Fastening
This domain tests layout control, panel handling, and fastener selection and spacing. Expect questions that give a slope, wind zone, and profile and ask for the correct spacing or the reason a panel failed.
Layout
Square from the eave and one gable end; check diagonals. Snap a chalk line for the first panel and every fifth panel. Set side laps facing away from the prevailing wind. Plan cuts at hips and valleys, and keep panel length inside shipping and handling limits.
Fastening
- Through-fastened: #12 or #14 self-drilling screws with EPDM washers in every low rib; about 6 in. on center at endlaps and ridge, 12 in. in the field, tighter in edge and corner zones.
- Standing seam: concealed clips spaced per the manufacturer's span table, often 24–60 in. on center.
- Penetration: 1 in. into wood, three threads through steel. Drive until the washer just compresses; never dimple the panel.
Handling
Lift with spreader bars; do not drag bundles. Store on a slope, blocked, with straps over the bundle but not over panel edges.
Worked example
A 3:12 through-fastened roof in a 115 mph region. Edge zones take 6 in. spacing along rake and eave, 12 in. in the field, plus a stitch screw at mid-span of each side lap. Any overdriven screw must be corrected before the next panel is placed, because the dimple traps water and voids the warranty.
Traps
Fastening both ends of a panel so it cannot move; walking on the flat pan instead of the ribs; and using fasteners too short to penetrate the deck when insulation is present.