The most expensive planning mistakes in London happen before any drawing is made: buying a house assuming the loft can be converted, briefing a builder for a six-metre extension in a conservation area, or spending a year on a change of use the Local Plan resists. A feasibility study answers the big questions early and cheaply. Where policy is genuinely uncertain, a pre-application enquiry puts those questions to the council itself.
What does a feasibility study tell me?
Every study starts with the site. We pull the planning history for the address and its neighbours, the constraints map (conservation area, Article 4 direction, flood zone, tree preservation orders, listed buildings nearby) and the policies in the Local Plan, the London Plan and any supplementary design guidance the borough uses. We then draw two or three scaled options, from the safe permitted development scheme to the ambitious one, and assess each against policy and against what the council has approved or refused nearby.
Each option gets a planning risk rating and a build cost range based on current London rates. The report ends with a recommendation and next steps, whether that is an LDC, a householder application, a pre-app or a decision not to proceed. Our guides on permitted development and conservation areas cover the rules the study applies.
When should I ask the council for pre-application advice?
Pre-application advice is a paid service in which a planning officer reviews your outline proposal and gives a written, non-binding view before you apply. It is worth using when:
- the proposal departs from permitted development and local guidance, for example a full-width dormer in a conservation area in Camden or a two-storey side extension in Barnet;
- you are proposing a change of use, a new dwelling or a flat conversion where policy is finely balanced;
- neighbours or a previous refusal suggest the council has concerns you want to address up front;
- the cost of a wrong application, including the lost time, is high.
It is rarely worth it for a standard rear extension or a rear dormer that fits the guidance. In those cases we go straight to the planning documentation stage.
Fees vary by borough and typically fall between £150 and £600 for householder pre-apps, with larger schemes charged on a sliding scale; verify the current fee on the council’s website before applying. Responses usually arrive within 4–6 weeks. Our pre-application guide explains how each borough runs the service.
What’s included
For a feasibility study you receive the desktop appraisal, policy review, scaled options, planning risk assessment, cost ranges and a written report you can share with a lender or solicitor. The pre-application package adds a concise drawing set and covering statement pitched at the level of detail officers want, submission to the council, attendance at any meeting, and a debrief letter translating the officer’s response into a clear recommendation. If you proceed to a planning application with us within six months, the feasibility fee is credited against the planning fee.
What’s not included
Council pre-application fees are paid directly to the borough. A measured survey is quoted separately where accurate existing drawings are not available, though many studies can be done from lease plans and site photographs. Detailed cost plans, specialist reports and full planning drawings follow the feasibility stage and are quoted once the preferred option is chosen.
Process and timeline
| Stage | Feasibility only | With pre-app |
|---|---|---|
| Quote | Within 24 hours | Within 24 hours |
| Desktop appraisal | 1 week | 1 week |
| Options and report | 2–3 weeks | 2–3 weeks |
| Pre-app drawings and submission | – | 1 week after report |
| Council response | – | 4–6 weeks |
| Total | 3–4 weeks | 9–12 weeks |
Fees
A feasibility report for a house extension or loft is a fixed fee. Conversions, changes of use and small new builds, where unit counts and policy carry more weight, sit in a higher band, and the pre-application package is priced on top, excluding the council’s fee. All figures are our professional fee only, excluding VAT. Ask through the quote tool or contact page and we confirm the figure in a written quote within 24 hours.
Related guides and example projects
- Pre-application advice from London councils
- Permitted development rights in London
- Conservation areas: extensions and lofts
- Class MA: office to residential
- Planning documentation
- Borough pages: Camden, Barnet, Ealing and Richmond upon Thames
Tell us the address and what you are hoping to achieve, and we will confirm whether a feasibility study or pre-app is the right first step and send a fixed-fee quote within 24 hours. Get your instant estimate.
