Metal Shingle Products, Materials, and Manufacturer Specifications
This domain tests whether you can select a metal shingle system and defend the choice from published data rather than a sales sheet. Expect questions on substrates (26- and 24-gauge galvanized steel, Galvalume, aluminum, copper, zinc), finishes (PVDF, SMP, stone granules), minimum slope, exposure, listed wind/impact/fire ratings, and the accessories that make a system complete.
Material and product rules
- A metal shingle is a modular stamped or folded unit with an interlock and a defined exposure; coverage width × exposure gives installed area per unit. Order by installed squares, then add the manufacturer's waste and starter/hip/ridge quantities.
- Gauge alone does not determine performance. Uplift resistance depends on profile, clip and fastener schedule, deck attachment, and the tested assembly. Ask for the manufacturer's wind table for the actual span and edge zone.
- Finish and substrate warranties are separate. A 30-year chalk-and-fade finish warranty does not cover corrosion at cut edges or fastener heads.
- Use only the manufacturer's fasteners, closures, and touch-up. Mixing metals, such as copper with aluminum or galvanized with copper, creates galvanic corrosion.
Worked example
A 40-square job specifies 24-gauge shingles at 24 in. on center for a 115-mph Exposure C site. The manufacturer's table gives 24 in. o.c. at 110 mph Exposure B only. The correct response is not to add sealant; it is to request the Exposure C table, reduce fastener spacing or add clips as published, or obtain an engineer's letter. The governing document is the current installation manual, not a previous job's detail.
Traps
Buying by gauge; assuming a stone-coated product has the same details as a painted one; omitting hip/ridge and starter from the takeoff; using a generic butyl sealant where the manual specifies a neutral-cure silicone.