Glossary
Structural engineer fees on a London extension in 2026
Independent fee for structural calcs and drawings. Required for most extensions and loft conversions.
Independent fee for structural calcs and drawings. Required for most extensions and loft conversions.
The number of structural elements, whether foundations need designing rather than adopting a standard detail, whether trees on shrinkable clay require a deeper or piled solution, and whether temporary works and a method statement are needed. A single beam over a rear opening sits at the bottom of the range; a basement with underpinning and ground-movement assessment at the top.
Calculations, structural drawings, a beam and padstone schedule, and responses to building control queries. Site visits during construction, temporary works design and revisions arising from a contractor's substitution are usually charged separately — worth clarifying before appointment.
Alongside the planning fee of £548, building control at £500 to £1,200, a party wall award commonly £900 to £1,400 per neighbour, and the drawing package.
A worked Islington example of structural engineer fee: with 40 conservation areas — the Barnsbury Conservation Area and the Canonbury Conservation Area among the best known — London Borough of Islington (Islington Council) sees structural engineer fee constantly, and an Article 4 direction is in force there, so permitted development cannot be assumed. Where structural engineer fee pushes a Islington scheme out of permitted development, the route becomes a £548 application decided in 8 weeks rather than a £249 prior approval in 6 weeks.
| Typical extension or loft | |
|---|---|
| Basement or underpinning | £2,000+ |
| Usually included | Calculations, drawings, beam schedule, BC queries |
| Usually extra | Site visits, temporary works, contractor substitutions |
| Our calculations from | |
| Complete package |
Foundation design and temporary works are the main variables, not the beam count.
Responses to queries should be included; confirm at appointment.
Pick a slot that suits you. No obligation and no sales pressure, just straight answers on your planning route.
