Engineering & Design
Steel Materials for Pre-Engineered Buildings
Steel materials for pre-engineered buildings are the plate, hot-rolled coil, hot-rolled sections, metallic-coated sheet, bolts and anchor rods used to make frames, secondary members, cladding and connections. Each is specified to a recognized national or regional material standard that defines strength, chemistry, toughness and coating.
Key facts
- Built-up frames are welded from plate or coil cut into flanges and webs.
- Purlins and girts are roll-formed from high-strength coil, often with a zinc or zinc-aluminum coating.
- Roof and wall panels use thin metallic-coated sheet, frequently with a factory paint system.
- Material grades must match the design code family named for the project.
- Mill certificates trace each heat of steel to its specified standard.
Which steel products go into a metal building
Primary frames are typically built-up I-sections. Flanges and webs are cut from plate or hot-rolled coil and joined by automatic welding, which lets the web depth taper along the member. Some frames, endwall members and bracing use hot-rolled sections, angles, rods, pipes or hollow sections.
Secondary members such as Z-purlins, C-girts and eave struts are cold roll-formed from high-strength coil. Cladding is roll-formed from thin sheet with a metallic coating and usually a paint finish. Connections use structural bolts, and the building is anchored with anchor rods cast into the foundation.
How US and Canadian grades are described
In North America plate and coil for built-up members are commonly specified to ASTM standards such as A572 or A1011 high-strength low-alloy grades, while hot-rolled sections often use A992 or A572. Coated sheet for purlins and panels is specified to ASTM A653 for zinc coating or ASTM A792 for aluminum-zinc alloy coating. Bolts follow ASTM F3125, and anchor rods commonly follow ASTM F1554.
In Canada structural plate and sections are typically supplied to CSA G40.21, with grades such as 350W, and ASTM grades are also accepted where the design standard allows. Material must be compatible with the design rules of CSA S16 or CSA S136.
How Australian/NZ and European grades are described
In Australia and New Zealand, plate is commonly specified to AS/NZS 3678, hot-rolled sections to AS/NZS 3679.1, and hot-rolled coil to AS/NZS 1594. Metallic-coated sheet for purlins and cladding is specified to AS 1397, which defines both base steel strength grades and coating classes.
In Europe, hot-rolled structural steels are specified to the EN 10025 series, with S355 a common grade for frames. Continuously hot-dip coated strip for cold-formed members and sheeting is specified to EN 10346, which covers zinc, zinc-aluminum and aluminum-zinc coatings. EN 1090 requires the material and its documentation to match the execution class.
Why toughness, weldability and traceability matter
In cold climates or for heavily loaded welded members, the engineer may specify notch toughness so the steel resists brittle fracture. Weldability depends on chemistry, and the welding procedure must suit the grade and thickness.
Traceability links each part to its mill certificate. Inspectors and authorities increasingly expect this record, particularly under EN 1090 in Europe and AS/NZS 5131 in Australia and New Zealand.
Can grades from different systems be substituted
Grades from different standards can have similar nominal strengths but differ in chemistry, toughness testing, tolerances and certification. Substitution is possible only when the engineer confirms that the alternative satisfies the design code in force and the authority accepts it.
World Steel supplies PEB structures, components and related products designed to the code specified for the project, and material grades are selected to suit that code.
Material points to state in an RFQ
- The design code family, which drives acceptable material standards.
- Any owner requirement for specific grades or mills.
- Lowest service temperature where toughness may be needed.
- Required metallic coating class for secondary members and cladding.
- Bolt and anchor rod grades and finishes.
- Documentation needed at delivery, such as mill certificates.
Frequently Asked Questions
Why are pre-engineered frames built up instead of using rolled beams?
Built-up members let the web depth and flange size vary along the frame to follow the forces, which places steel only where it is needed. Rolled sections have a constant shape and are used where that suits the member.
Are purlins galvanized?
Purlins and girts are commonly roll-formed from zinc-coated or aluminum-zinc coated coil, or from uncoated coil that is primed. The choice depends on the environment and the specification.
Can a European project accept ASTM steel?
Acceptance depends on the authority and the design code. Under the Eurocodes and EN 1090, materials are expected to conform to the referenced EN standards, so substitution requires engineering justification and approval.
Engineering content is general guidance. Every World Steel building is designed by qualified engineers to the code and loads of the project.
