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Building regulations for steel buildings

A new industrial, storage or workshop building in England needs Building Regulations approval. This is a plain-English checklist of the parts that matter most for a steel portal frame building. It is a guide, not an approval.

Part A: structure

The frame, connections and foundations must be designed for the snow and wind loads at your site, which depend on altitude and exposure. Steel should be fabricated to BS EN 1090 with UKCA or CE marking.

Part B: fire safety

• Travel distance to an exit: in industrial and storage buildings, 25 m with only one direction of escape, or 45 m where there are alternatives.
• Exit doors must be wide enough for the number of people: 750 mm clear for up to 60 people.
• Walls near a site boundary may need to be fire-resisting (the space separation check).
• A mezzanine needs a protected escape route or a short enough travel distance to the stair.

Part L: energy (heated buildings)

A heated building also needs an SBEM energy calculation and an air-tightness test (limit 8 m³/(h·m²) at 50 Pa). Unheated storage buildings are normally outside the energy rules. The Future Buildings Standard (Approved Document L 2026) applies to work after 24 March 2027, with transitional arrangements for projects already submitted.

Part K: stairs and guarding

Stairs to a mezzanine need handrails, and the open edge needs guarding at least 1,100 mm high.

Part M: access

At least one accessible entrance with a level threshold (15 mm maximum upstand) and enough clear width, typically 1,000 mm for a new building.

Part H: drainage

Gutters and downpipes sized to BS EN 12056-3 for the roof area, discharging to a soakaway or approved drain.

Part S: electric vehicle charging

New non-residential buildings with more than 10 parking spaces need EV charge points and cable routes.

Exemptions

Buildings used only for agriculture, meeting the distance and fire-exit conditions, are usually exempt. See agricultural steel buildings. Wales, Scotland and Northern Ireland have their own regulations.