Short answer
You need a structural engineer whenever the strength, stability or load path of a building is affected. In practice that means removing or altering a load-bearing wall, forming a new opening, building an extension or loft conversion, adding significant new loads, underpinning, or investigating cracking and movement. Building control will normally expect supporting calculations for that work, and an architect's drawings alone do not provide them. If you are unsure, a short conversation is usually enough to establish whether engineering input is required and, if so, how much.
Branded guidance note, prepared for project records and circulation to your team.
Work that almost always requires an engineer
- Removing, reducing or forming an opening in a load-bearing wall
- Extensions, loft conversions and basement alterations
- New beams, columns, lintels or padstones
- Alterations affecting foundations, retaining structures or drainage under load
- Investigation of cracking, deflection, movement or water damage
Work that usually does not
The difficulty is that a wall's role is not always obvious from inside the room. Floor joist direction, the position of walls above, and whether the wall continues to foundation level all matter. Where there is any doubt, it is far cheaper to check than to discover the answer during demolition.
- Non-structural partition removal, where the wall carries nothing above
- Redecoration, replacement fittings and like-for-like repairs
- Non-loadbearing garden structures and lightweight canopies
How BES is typically involved
- An initial conversation or site visit to establish what is actually load-bearing and what is proposed.
- Load take-down, member design and calculations issued in a form building control accepts.
- Sketches or drawings for pricing and construction, and answers to contractor queries as work proceeds.
Typical process
- 01Initial enquiry and review of available drawings or photographs
- 02Site visit or desktop appraisal, depending on complexity
- 03Load take-down and structural design
- 04Issue of calculations and sketches for building control and pricing
- 05Support during construction
Common misconceptions
Commonly assumed
“My builder has done this before, so calculations are not needed.”
In practice
Experience is valuable, but building control require calculations signed by a competent engineer, and insurers and future purchasers may ask for them.
Commonly assumed
“The architect covers the structure.”
In practice
Architects design the space and the detail; the structural design and its calculations are a separate discipline and a separate appointment.
Related tools and services
Resource Centre tool
Structural Project Navigator
Answer a few straightforward questions to identify the likely structural engineering input, information requirements and next steps for your project.
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Project Information Builder
A guided ten-step wizard that prepares a complete Project Information Pack — client details, site, scope, programme and documents — ready for quotation and appointment.
Start Information Builder →Related questions
Discuss your project
General guidance only goes so far. Describe your building and what you are planning, and you will receive project-specific advice from a Chartered Structural Engineer.
Discuss Your Project →Next scheduled review August 2027
Disclaimer
Indicative result only. The calculation depends on the assumptions and information entered and does not constitute structural design or professional advice. Do not use the result for construction, procurement, Building Regulations submissions or safety-critical decisions. All results must be independently verified by a suitably qualified structural engineer before being used for design, construction or regulatory purposes. Bebbington Engineering Studio Ltd accepts no responsibility for reliance placed on unverified results.