Steel Alloys

Why Steel? Steel may be the best roof and wall cladding material when you consider its high strength-to-weight ratio, low thermal movement, and ability to be formed by power equipment or hand tools.  Although most light-gauge steel sheet is both zinc-coated (corrosion resistance) and color-coated, steel is typically the low-cost architectural-metal.   Thanks to the possibility of hundreds of colors and it’s low-cost market position, prepainted steel provides architects with endless design possibilities.  While all exterior cladding materials have some negative environmental impact, the abundance of steel’s ingredients (iron ore, limestone, & coal) are readily available in many parts of the world.  Learn more about the environmental impact of SSAB steel by downloading the latest GreenCoat EPD.


Steel for Architectural Applications.

All standing-seam pans, corrugated panels, interlocking tiles, and embossed shingles made from prepainted steel is classified as “mild steel”.  Within this broad category, nearly all North American architectural steel profilers use a “structural” quality steel (typically Grade 40 or Grade 50, a few Grade 80) with a relatively high tensile strength.  While pre-engineered buildings and “structural metal” roofing require high-strength metal to span open framing and resist impact loads (hail), the yield strength is a more important property for roofing and wall cladding where solid substrates are present.  Specifying a low-carbon and “low-yield” strength painted steel has only been available in the Nordic countries.  “Architectural” metal roof and wall applications that specify mechanical-seam profiles (single-lock & double-lock) are provide higher quality installations when a softer metal is used.  Traditionally those metals have been the crafted metals (copper, zinc, lead).  “Foldable” steel with a yield strength of 18 ksi (and 45 ksi tensile) is now available in North America.  A softer steel (with virtually no “spring back”) allows better seam folding and crafted detail execution.  GreenCoat PLX BT steel helps the installer create a higher quality steel roof or wall cladding.  In addition, all PLX grade steel also has a heavy G115 (better than G90) galvanizing layer below the paint.




SSAB (Swedish Steel) produces GreenCoat™ color-coated steel for architectural sheet metal applications such as double-lock standing seam (DLSS), single-lock standing seam, and applications requiring a crafted metal quality installation.  Choose one of the following PLX “foldable” steels:


Architectural applications requiring the highest degree of flatness, panel clips that elevate the pan above the substrate, or “snap-seam” panels that rely on the memory of the metal should specify a structural-grade ASTM A653 (Grade 40 = S280GD+Z) steel.

  • S280GD+Z, SS Grade 40 (both have 40 ksi yield)
  • S320GD+Z (46 ksi), SS Grade 40 (min. 40 ksi)
  • S350GD+Z (50 ksi), SS grade 50 (min. 50 ksi)

Standard GreenCoat™ color-coated products are available with S280GD+Z  (G90) galvanized steel:

See the online color chart for standard colors for individual GreenCoat product lines:   GreenCoat™ color-coated steel (international site).


Who is SSAB?

SSAB is a Nordic-based steel company which offers innovative and value-added products for the heavy construction, automotive, and building markets.  With production facilities in Sweden, Finland, & USA, SSAB is a vertically integrated company producing innovative products for specialty markets including the building exteriors.  Operating their own steel production operations, hot & cold rolling mills, galvanizing, and coil-coating lines, SSAB assumes more control of the ingredients and production that go into their products and prevention of harmful or non-renewables materials during the steel making or color-coating processes than most other suppliers.

GreenCoat™ is a trademark of the SSAB group of companies

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