Most architectural quotes in London are not comparable. Here is every line item in ours, and every one we have seen charged separately elsewhere.
When you ask three practices what a single-storey rear extension costs, you will get three numbers that look similar and mean entirely different things.
One quotes for drawings alone. The survey is extra. Submitting the application is extra. If your property sits in a conservation area and needs a Design and Access Statement, that is extra again. And when the drawings are approved and you need structural calculations, you are handed the name of an engineer and a second invoice from a different company.
We price the whole stage, once. The survey is included. The submission is included. Revisions are included. Our structural engineers are chartered members of the Institution of Civil Engineers and sit in our office, not on a referral list.
This page sets out exactly what you get, exactly what you do not, and what a typical job comes to in total. No quote we issue contains a line you have not seen here first.
| Line item | Salstan, single-storey rear extension | Typically charged separately |
|---|---|---|
| Planning drawings | Included | £900 |
| 3D measured survey (LiDAR) | Included | £350 |
| Design meetings and revisions | Included, unlimited within scope | Per round, or capped |
| Application preparation and submission | Included | £231 |
| Design and Access Statement, conservation areas | Included | £350–£900 |
| Structural engineering | In-house, chartered | Referred out, separate company, separate invoice |
| Planning refused? | Second iteration at half our original fee | New fee |
| Total to planning decision | £900 + VAT | £1,831–£2,381 + VAT |
Comparison based on published 2026 price lists from London practices offering the same scope. Council application fees are set by government and excluded from both columns.
Refused? You never pay our full fee twice. A second iteration of the same scope is charged at half the original fee, agreed before we start.
Three things sit outside the fee, and we would rather you heard it here than in an invoice.
Set by government, not by us. We pass them on at cost with the receipt. Nobody can include these and nobody should pretend to.
This is a separate stage that begins once your planning permission is granted, and it is priced separately because not every client needs it from us. The difference is that when you do, it is the same team, in the same building, working from the same model. Your drawings are not reinterpreted by a stranger.
Quoted once the technical design is complete and we know what we are actually building. See our construction service.
Not in a conservation area.
| Stage | Fee |
|---|---|
| Planning: survey, drawings, revisions, submission | £900 + VAT |
| Council application fee | At cost, currently set by government |
| Building Regulations and structural design | Quoted on approval |
| Construction | Quoted on technical design |
If a quote you have received elsewhere does not break down this way, ask for it line by line before you compare it with ours.
Speak with Salstan about your planning, architecture, structural engineering or building regulations project. We’ll help you understand the next steps and provide a clear, no-obligation quote.
We are a full-service, turnkey firm specialising in Architecture, Planning Permission, Building Regulations, Structural Design, Civil Engineering and Construction.