Structural engineer cost in the UK (2026): calculations, beams and reports
3 min
7
September 2026
Key figures in this guide
One-minute decision
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Use the guide to decide the role, then search for the right type of professional rather than asking everyone for the same thing.
Find professionalsA structural engineer costs £750 - £2,500 for a typical extension or loft conversion in 2026, and £450 - £900 if you only need calculations for a single beam. A written structural report on a crack or movement is usually £550 - £1,200.
Engineers price by the number of structural elements they have to design, not by the size of your house. One steel beam is cheap. A wraparound extension with three openings, new foundations and a loft above is not.
Structural engineer costs in 2026
| Job | Typical 2026 cost | What you get |
|---|---|---|
| Single beam calculations | £450 - £900 | Calculations and a sketch for one opening, for building control |
| Two or three openings | £750 - £1,500 | Calculations, beam and padstone sizes, connection details |
| Single-storey extension | £900 - £1,800 | Foundations, beams, lintels, roof structure, full calculation pack |
| Two-storey extension | £1,400 - £2,600 | As above with floor and wall design |
| Loft conversion | £900 - £2,000 | Floor joists, steels, dormer framing, existing roof checks |
| Basement or underpinning | £2,500 - £6,500 | Temporary works, retaining design, party wall input |
| Structural survey or report | £550 - £1,200 | Site visit and written report on cracks, movement or removal feasibility |
| Site visit during the build | £250 - £450 per visit | Inspection of foundations, steelwork or ties |
Add 15 - 25 per cent in London. Same-week turnaround usually carries a premium.
When you need a structural engineer
- Removing or widening any load-bearing wall
- Any extension, because foundations and beams need designing
- A loft conversion, because the existing joists are not designed for a floor
- Cutting into a roof for a dormer or large rooflight
- Underpinning, basements, or building close to a neighbour
- Cracks, sagging floors or bowing walls you want assessed before buying or building
When you probably do not
- Studwork partitions that carry nothing
- Like-for-like window replacement in the same opening
- Kitchens, bathrooms, wiring, plastering and decoration
How the engineer fits with everyone else
- 01The architect or designer settles the layout.
- 02The engineer designs the structure that makes that layout stand up.
- 03Building control checks the calculations before work starts and inspects on site.
- 04The builder prices the steel, foundations and any temporary support.
Get the calculations before you tender. Builders pricing without them either guess high or leave the structure out, and both distort your quotes.
What affects the fee
- The number of structural elements, not the floor area
- Whether a site visit is included, and how many
- Whether foundations near trees or drains need special design
- Whether the engineer liaises with building control and the party wall surveyor
- Revisions after the design changes, which are usually charged extra
What to check before you appoint
- 01Are you chartered, with IStructE or ICE?
- 02Does the fee include calculations, drawings and building control queries?
- 03How many revisions are included if the layout changes?
- 04What is the turnaround from instruction to issued calculations?
- 05Is professional indemnity insurance in place, and at what level?
Find a structural engineer for your project
Renovome turns your plans into a brief that states exactly which structural elements are involved, so engineers quote for the same work and you can compare fees and turnaround properly. Then find engineers near you and appoint with confidence.
Last reviewed: September 2026