Structural work & steels Cost Calculator

For a single beam or RSJ calculation — the usual job when removing one load-bearing wall — expect £300–£600 in 2026. Two or more beams (a full knock-through) typically run £500–£900. The fee should cover the site visit or measured drawings, the sizing calculations, the steel specification and bearings, and a signed calc pack that building control will accept. Add roughly 15–25% in London and the South East.

A structural engineer calculates loads and designs structure — beam sizes, foundations, whether a wall can safely come out — and produces the calcs building control needs. A building surveyor inspects a property's overall condition and defects (damp, roofing, general disrepair) and advises on repairs, but doesn't design new structure. If you're changing the building, you want an engineer; if you want to know the condition of a property before buying, you want a surveyor. For a structural-specific concern like a crack, a structural engineer's inspection is the right call.

Yes, almost always. An existing loft floor was designed only to hold up the ceiling below, not to be a habitable room, so new floor joists or beams are needed — plus roof alterations and often a supporting beam at the ridge or eaves. Building control will require structural calculations. Budget £500–£1,200 for the structural design element of a loft conversion, separate from the architect's and builder's costs.

It depends on the job. A single beam calc is often ready in 3–7 working days after the site visit. A full structural survey report usually takes 1–2 weeks, and extension or loft design packages 2–4 weeks. Subsidence investigations can take longer if the engineer needs a period of crack monitoring (sometimes several weeks) to confirm whether movement is ongoing. Ask for a turnaround time in writing when you get your quote.