A structural engineer is a professional who designs and calculates the load-bearing elements of your project — new steel beams, altered foundations, roof structure, lintels, and any element that carries structural load. For most extensions, loft conversions, and structural alterations in London, a structural engineer's design is mandatory for Building Regulations compliance.
When Do You Need a Structural Engineer?
A structural engineer is needed whenever:
- A wall (load-bearing or potentially load-bearing) is being removed or opened up
- A new beam or lintel is being installed to carry structural load
- A loft conversion requires new structural floor joists and roof alterations
- A new extension requires new foundation design
- Any structural element is being altered, removed, or added
Even seemingly simple works — removing a chimney breast, widening a doorway in a potentially load-bearing wall, or adding a large rooflight to a flat roof — require structural engineering design.
Qualifications to Look For
A competent residential structural engineer should hold:
- Chartered status with the Institution of Structural Engineers (MIStructE or FIStructE) or the Institution of Civil Engineers (MICE or FICE)
- Professional Indemnity Insurance — confirm the level of cover before appointing
Avoid using a "structural engineer" who is not professionally qualified — errors in structural design can have serious safety consequences and may not be identified until a failure occurs.
How to Find a Structural Engineer
- From your architect: Architects regularly work with structural engineers and can recommend trusted professionals they have collaborated with
- From your contractor: An experienced principal contractor typically has a structural engineer they work with regularly — the advantage is that the engineer and contractor already understand each other's working practice
- IStructE directory: The Institution of Structural Engineers publishes a directory of members at istructe.org
What to Check Before Appointing
- Professional qualifications and chartered membership
- Relevant residential project experience (a structural engineer specialising in commercial warehouses may not be the best choice for a Victorian terrace loft conversion)
- Professional indemnity insurance level (minimum £1m for residential projects)
- Typical fee for the scope of work (obtain 2–3 comparable quotes)
- Turnaround time for calculations — Building Control submissions can be delayed if the engineer is slow to produce drawings
Typical Structural Engineering Fees
| Scope | Approximate fee |
|---|---|
| Single beam calculation (steel or timber) | £250–£600 |
| Loft conversion structural design (floor, roof alterations) | £700–£1,500 |
| Extension foundation and structural design | £800–£2,000 |
| Complex structural works (multiple elements, phased review) | £1,500–£5,000+ |
Working with Your Structural Engineer
The structural engineer typically works alongside the architect — the architect produces the layout and aesthetic design, the engineer designs the structural elements within that layout. For design-and-build projects, the contractor coordinates between engineer and programme.
rcbGroup
rcbGroup coordinates structural engineering as part of the principal contractor service — instructing and managing the structural engineer to ensure drawings are delivered to the programme and Building Control submissions are made at the right time.