Covering · AHR, ALR, mastic, closures
Covering and trim
26-gauge Galvalume, 36″ coverage. Nippers, not grinders. Closures at the eave. Job drawings still govern the lap and the fastener pattern.
Do not grind the panel
Field-cut or miter panels with non-abrasive tools — nibblers or tin snips. Abrasive grinders, saws, shears, or scissors can damage Galvalume or paint and throw metal shavings that rust the panel. Unapproved cutting can void the finish warranty.
AHR panel
High-rib covering: 36″ net coverage, major ribs 1¼″ deep at 12″ on center, 26 ga Galvalume (ASTM A792), 80 ksi. Minimum roof pitch ½:12. Typical agricultural and commercial wall and roof panel in this system.
ALR panel
Low-rib covering: 36″ net coverage, major ribs ¾″ deep at 9″ on center, extended purlin-bearing side lap, two minor ribs in the flat. Used on roof at 2:12 minimum pitch and on walls as specified.
Roof fasteners (typical — confirm on the order)
| Use | Fastener |
|---|---|
| Panel to secondary | #12 self-drilling, hex washer head, sealing washer, 1¼″ long, 20-year coating, painted head when the panel is painted |
| Panel-to-panel stitch (ALR) | #12 × ¾″ self-drilling, hex washer head, sealing washer |
| Stitch (AHR / trim) | #14 × ⅞ or as drawn |
Trim and flashing
- Color-coated trim is 26 ga (some flashing 29 ga) at eave, ridge, rake, and wherever the order documents show it.
- Parapet counterflashing and tie-in flashing to existing buildings are not furnished.
- Exposed trim is galvanized or Galvalume strip.
- Exterior gutters and gable flash ship in 20′ lengths wherever possible.
Sealants
- Mastic tape is an isobutylene-copolymer rubber, pressure-sensitive.
- Side-lap tape: ³⁄₃₂″ × ½″ (AHR) or ⅜″ × ³⁄₃₂″ (ALR) as specified on the order.
- End-lap tape: ³⁄₁₆″ × ¾″.
- Tube sealant is non-hardening elastomeric, used at trim and flashing end laps.
Closures
Closed-cell polyethylene foam, die-cut to the panel. Furnished at the eave of roof and wall panels. Inside or outside as the ridge and eave details show.
Erection care
- Great care and attention to the details on the erection drawings.
- Thermal expansion and contraction matter at a roof tie-in to an existing building. Tie-in flashing is typically not in the package.
- Not every condition can be drawn. Sealant and caulk as the actual condition requires.
- Swarf, cuttings, and fasteners off the roof at the end of each day.