The short answer
You usually do need a chartered structural engineer whenever you change or assess the structure of a building. That includes removing a load-bearing wall, fitting an RSJ or steel beam, forming a large opening, loft conversions and extensions, and underpinning or chimney removal — because Building Control normally requires signed structural calculations before the work is approved. You also need one to investigate cracks, movement or subsidence when a survey flags a structural concern. You generally don't need one for non-structural work — moving a stud partition, cosmetic repairs or a like-for-like replacement — where a competent builder or architect is enough.
The simple test is whether the work touches the building's structure or load paths. If it does, an engineer's calculations are usually required; if it doesn't, they're usually not.
When an engineer is needed
- Load-bearing wall removalyes — signed calcs
- Beam / RSJyes — beam design
- Loft / extensionusually yes
- Cracks / movementyes — assessment
- Stud partitionusually no
Work that usually needs an engineer
- Removing a load-bearing wall: Building Control normally requires signed calculations for the beam and supports.
- Fitting a beam or RSJ: the beam must be sized for the loads it carries — that's an engineer's calculation.
- Loft conversions and extensions: new floors, openings and roof alterations change the load paths.
- Cracks, movement or subsidence: an engineer assesses whether it's structural and what to do.
- Underpinning, chimney removal, large openings: all alter how the building carries load.
| Job | Engineer needed? |
|---|---|
| Remove a load-bearing wall | Yes — signed calcs |
| Fit a beam / RSJ | Yes — beam design |
| Loft conversion / extension | Usually yes |
| Investigate cracks / movement | Yes — assessment |
| Move a stud (non-load) wall | Usually no |
General guidance — confirm your own case with Building Control. Source: HomeOwners Alliance.
Why the calculations matter
For structural work, Building Control checks the design before and after the job — and a completion certificate is normally only issued once signed calculations are in place. That certificate matters beyond safety: when you come to sell, solicitors and lenders typically ask to see it, and missing paperwork for a removed wall or added beam can hold up a sale. Getting an engineer involved early is usually cheaper and simpler than retro-fitting calculations later.
Frequently asked questions
Do I always need a structural engineer to remove a wall?
If the wall is load-bearing, yes — Building Control normally requires signed structural calculations for the beam and supports. For a non-load-bearing stud partition you usually don't, though it's worth confirming the wall is genuinely non-structural first.
Do I need a structural engineer or an architect?
They do different jobs. An architect designs the space; a structural engineer provides the load and beam calculations where the structure is altered. On larger projects you often need both, working together.
What happens if I skip the calculations?
Building Control normally won't issue a completion certificate without signed calculations for structural work. That can cause problems when you sell, as solicitors and lenders typically ask to see the certificate for a removed wall or added beam.
Sources & further reading
Figures on this page are typical UK ranges drawn from published sources and depend on your specific project. They are guidance, not a quotation.