In short
Chartered Engineer (CEng MIStructE) working with the practice on calculations, party wall surveying and basement underpinning.
What does the structural engineer actually sign off?
The load path, to building control rather than to planning. Calculations are submitted with a full plans application, which must be decided within five weeks, and a domestic floor converted to habitable use carries an imposed load of 1.5 kN/m².
| Work | Calculations required | Basis |
|---|
| Removing a load-bearing wall | Yes | Beam sizing and padstones, Part A |
| Forming an opening in a rear wall | Yes | Lintel or goalpost frame, Part A |
| Rear dormer cutting roof rafters | Yes | Trimming and floor loading, Part A |
| Loft floor to habitable use | Yes | 1.5 kN/m², BS EN 1991-1-1 |
| Underpinning next to a neighbour | Yes | plus a party wall notice |
| Non-structural stud partition | No | no change to load path |
| Full plans decision period | — | 5 weeks, or 2 months by agreement |
Sources: the Building Regulations 2010 (as amended), Schedule 1 Part A and regulation 14; Approved Document A; BS EN 1991-1-1 with its UK National Annex; the Party Wall etc. Act 1996. Read at 1 September 2026. The planning application does not assess structure at all, at first instance or on appeal.
When a structural engineer is legally required
There is no statute that says “you must appoint an engineer”. What exists is Part A of the Building Regulations 2010, which requires that a building be constructed so that loads are sustained and transmitted to the ground safely. In practice, building control will not pass a plan check that removes a load-bearing element without calculations behind it, and those calculations have to come from someone competent to produce them.
That threshold is crossed by almost every rear extension (the rear wall is load-bearing), every loft conversion (new floor joists span onto existing walls never designed for habitable loading), and every basement.
What a set of calculations actually contains
Load take-down from roof to foundation; beam sizing against bending, shear and deflection; padstone sizing so the point load does not crush the masonry beneath it; and a foundation check where new load reaches existing footings. Deflection is the one clients underestimate — a beam can be strong enough and still be rejected because it moves more than span/360, which is what cracks the plaster above a new opening.
Party wall surveying and the 1996 Act
The Party Wall etc. Act 1996 creates three notifiable categories. Section 1 covers building on the line of junction. Section 2 covers work to an existing party structure — cutting in a beam, raising, underpinning — and needs one month's notice. Section 6 covers excavation: within 3m of a neighbouring structure and deeper than its foundations, or within 6m where a 45° line from the base of their foundation would meet the excavation, and needs two months' notice.
If a neighbour dissents, or does not respond within fourteen days, a surveyor is appointed and an award is made. The award is a legal document that records the condition of the adjoining property before work and settles who pays for what afterwards.
Underpinning and basement retention
Underpinning transfers an existing foundation down to a lower bearing level, usually in a hit-and-miss sequence of one-metre bays so that no more than a quarter of the wall is unsupported at any moment. The design questions are retained height, groundwater, and the temporary condition — which is the condition that fails, not the permanent one. Where a borough operates a basement policy, a structural method statement covering that temporary sequence is required at application stage, not at construction stage.
How this looks in a named London borough
How structural engineer (consulting) plays out in Lambeth: London Borough of Lambeth (Lambeth Council) maintains 64 conservation areas, the Clapham Common Conservation Area and the Herne Hill Conservation Area among them, and an Article 4 direction is in force there, so permitted development cannot be assumed. Anyone dealing with structural engineer (consulting) at a Lambeth address is therefore working to a £548 householder application decided in 8 weeks, or a £249 prior approval over 6 weeks where structural engineer (consulting) still qualifies.
Structural Engineer (consulting) at a glance
Key figures for Structural Engineer (consulting)
| Role | Consulting Chartered Engineer (CEng MIStructE) |
|---|
| Scope | Calculations, party wall awards, underpinning design |
|---|
| Governing standard | Building Regulations 2010, Part A |
|---|
| Deflection limit | span/360 typical for habitable floors |
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| Party wall notice | 1 month section 2, 2 months section 6 |
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| Fixed fee from | |
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Questions about this role
Do I need structural calculations for a loft conversion?
Yes, in essentially every case. Existing ceiling joists are sized to carry a ceiling, not a habitable floor, so a loft conversion introduces new floor joists spanning onto walls that were not designed for that load. Building control will require the calculations at plan-check stage.
What happens if my neighbour refuses party wall consent?
Refusal is not a veto. If a neighbour dissents, or fails to reply within fourteen days, the Party Wall etc. Act 1996 requires that a surveyor be appointed and an award made. The award sets the conditions on which the work proceeds — it does not stop the work.
Is the structural engineer part of your practice?
No — the engineer is an independent consultant we work alongside. That independence matters on party wall matters in particular, where a surveyor acting for both owners must be impartial.
