Eleven grades.
One place that compares them.

GI, Galvalume, ZAM, PPGL — what's actually different, translated from the mill data instead of a spec sheet.

Articles in this pillar

MRM's 11-grade steel catalogue, translated into plain-language buyer content — our deepest content moat.

August 28, 20267 minute read

ZAM adds magnesium to the zinc-aluminum coating formula — here’s why that one addition changes corrosion performance so much.

August 28, 20267 minute read

Stainless steel sits at the top of the coil price range — here’s when that premium is genuinely worth paying for a roofing project.

August 24, 20267 minute read

All three coatings start as steel coil — here’s what actually separates GI, Galvalume, and ZAM in real-world performance.

July 1, 20262 minute read

Three coatings, three levels of corrosion resistance — and which one actually fits your climate.

June 21, 20262 minute read

Every term used across this site, defined in one place.

May 30, 20262 minute read

A decision framework for matching grade, coating, and budget to your site conditions.

February 9, 20267 minute read

A single loose panel is a repair. Recurring leaks, widespread corrosion, or a sagging deck usually mean it’s time to replace.

Explore the full 11-grade catalogue, mill-certified and ready to quote.