Steelwork Notes and Specifications for Domestic Projects

Every set of PorthouseDean structural documents includes a specification section covering all steelwork. The following notes apply to all steel elements unless stated otherwise in the calculations.

Steel Grades

– Beams and columns: Grade S355 to EN 10025 (also designated Grade 50B in older projects)
– Plates and cleats: Grade S275 mild steel
– Bolts: Grade 8.8 black bolts
– Fillet welds: E35 electrode (unless noted otherwise)

Fabrication Standard

All steelwork must be fabricated and erected in accordance with the latest edition of the National Structural Steelwork Specification (NSSS).

Fabricator workshop drawings must be submitted to PorthouseDean for approval before fabrication begins. Fees may apply for this review if it falls outside the original scope.

Cranked Elements

Where cranked beams are specified (common in chimney breast support details and loft conversions at eaves level), the cranked joint should be full-strength butt-welded by a suitably qualified fabricator in a workshop setting. The weld must be tested in accordance with relevant British or European standards. Cranked joints must not be made on site.

Column Fixings to Adjacent Walls

Where a column or post sits adjacent to a masonry wall:

– Option A: Weld or shot-fire frame cramps to the web or flange at 450 mm vertical centres, coursed into the masonry bed joints
– Option B: Weld mild steel brackets to the column flanges at 450 mm centres and bolt through the wall face using chemically bonded M12 anchors

Both methods achieve adequate lateral restraint of the column along its height. The choice is made by the contractor to suit site conditions.

Column Height and Foundation Connection

Where drawings show a column extending to “ground floor level,” this may mean the column extends below the finished floor level to a pad foundation. The column length is confirmed against the actual foundation depth once excavation is complete.

Corrosion Protection and Paint

Steelwork inside a heated building in a clean atmosphere: primer only (no galvanising required).

Steelwork in moisture-variable environments (cavity walls, shelf plates, external steelwork): hot-dip galvanising to the relevant European Standard (typically 85 µm, or a paint-applied system approved by Building Control).

Fire Protection

Fire protection of steelwork is specified by the architect. If intumescent paint is required (for example on exposed columns), the paint system must be compatible with any primer or anti-corrosion coating already applied.

Beams Installed in Pairs

Paired beams should be bolted together through the centre of their webs using M12 bolts at 500 mm centres with spacer tubes between the webs.

Questions About the Spec?

If something in your steelwork specification is unclear, contact PorthouseDean and we will explain.