Feasibility StudiesFrom £495
How much does a feasibility study cost in London?
A feasibility study for a London home costs our fixed £495, with no VAT charged. It checks your address for constraints, tests your ideas against the planning rules, sketches two or three options and tells you which route costs least in time and money, so you can decide before you pay for a full set of drawings.
The short answer: one fixed fee, before you commit to the rest
Our feasibility study costs £495. We take your address and your wish list, check the constraints on the site, test each idea against the rules and sketch two or three options at outline scale on the existing footprint. You get a written summary with our recommendation and the risks in plain English.
It is the least expensive point in a project to find a problem, which is the reason it exists. The study tells you the size limits that apply to your plot, the likely council fees and timescales and any levy exposure, so that the next decision, whether to buy a full set of drawings, is made on facts.
- Check the address
Conservation area, Article 4, listing, flood zone and trees are checked for your site.
- Find the route
Each idea is placed on permitted development, prior approval or a planning application.
- Sketch the options
Two or three options are drawn at outline scale on the existing footprint.
- Advise in writing
A plain-English summary sets out the options, the costs, the timescales and the risks.
Where a metre changes the answer
A single-storey rear extension may go no more than 3 metres beyond the rear wall of the original house, or 4 metres on a detached house, and no higher than 4 metres, without an application. Within 2 metres of the boundary the eaves may not exceed 3 metres. A study tests your idea against each of those on your plot.
Beyond those limits a house that is not on article 2(3) land can go to 6 metres, or 8 on a detached house, through prior approval at a council fee of £249. Article 2(3) land includes conservation areas, which is why the address check comes first. If the idea needs a full application, the council has 8 weeks and charges £548 for a householder one.
Costs people forget until late
The Community Infrastructure Levy can add a bill to larger schemes. Government guidance says it may apply where the gross internal area of new build is 100 square metres or more, though householder extensions that enlarge the main home are exempt. A study flags whether your scheme is anywhere near that line.
It also sets out the other likely costs: building regulations drawings, structural calculations and any party wall notices. Our posts on building regulations drawings and structural calculations show what each adds.
Why not just ask the council
You can, and for some projects it is the right first step. Councils run pre-application services, and government guidance notes that where charges are made they must not exceed the cost of providing the service. A study answers a different question: it is independent, it looks at several options, and it can be done before you have a design to put to a planning officer.
Where a pre-application meeting would help, the study tells you what to ask. It also tells you when not to bother, because the answer is already in the rules and the cost of the meeting would buy you nothing.
What happens after it
If the answer is yes, the next step is drawings: our rear extension drawings and lawful development certificate services cover the two commonest routes. If the answer is no, you have spent £495 instead of a full fee.
Our feasibility study page shows the service in detail. If you are buying a house and want the same question answered about a specific address, say so on the quote form.
Sources
Every figure in this article, where it comes from and a link to the original.
- 3 metres: GPDO 2015 Sch 2 Pt 1 Class A.1(f)(i): (source wording: "3 metres in the case of any other dwellinghouse"). www.legislation.gov.uk
- 4 metres: GPDO 2015 Sch 2 Pt 1 Class A.1(f)(i): (source wording: "4 metres in the case of a detached dwellinghouse"; and "exceed 4 metres in height"). www.legislation.gov.uk
- 2 metres: GPDO 2015 Sch 2 Pt 1 Class A.1(i): (source wording: "within 2 metres of the boundary of the curtilage of the dwellinghouse, and the height of the eaves of the enlarged part would exceed 3 metres"). www.legislation.gov.uk
- 6 metres: GPDO 2015 Sch 2 Pt 1 Class A.1(g): (source wording: "8 metres in the case of a detached dwellinghouse, or 6 metres in the case of any other dwellinghouse"). www.legislation.gov.uk
- article 2(3) land: GPDO 2015 Sch 2 Pt 1 Class A.1(g): the larger depths apply only to a dwellinghouse (source wording: "not on article 2(3) land"). www.legislation.gov.uk
- 8 weeks: DMPO 2015 art 34(2)(b): (source wording: "8 weeks beginning with the day immediately following that on which the application is received"). www.legislation.gov.uk
- £548: Statutory householder planning application fee, single dwellinghouse, from 1 April 2026. assets.publishing.service.gov.uk
- 100 square metres or more: PPG Community Infrastructure Levy, para 003: (source wording: "the gross internal area of new build is 100 square metres or more"). www.gov.uk
- they must not exceed the cost of providing the service: PPG Before submitting an application: (source wording: "Where charges are made they must not exceed the cost of providing the service"). www.gov.uk
Questions people ask
Is it a guarantee that the council will agree?
Do I pay VAT on your fee?
Do you visit the property?
Can I use it when buying a house?
What if the answer is that the idea will not work?
Photographs: Ben Hadfield (Unsplash License); Martin Sepion (Unsplash License).
Feasibility Studies: a fixed fee from £495
Read more on the feasibility studies service page, or send your address below and we reply within one working day.
Feasibility Studies
from £495
Every price is the full fixed fee you pay. No VAT is charged. Council application fees are paid to the council separately.
What you get
- A check of the address: conservation area, Article 4, listing, flood zone and trees
- The planning route for each idea: permitted development, prior approval or planning permission
- Two or three options sketched at outline scale on the existing footprint
- The size limits that apply to each, set out against your plot
- A written summary with our recommendation and the risks, in plain English