What you pay for, and why it comes first
Our fee is £545. For that we measure or take the existing plans of the house, look up the designations and rules that apply, and sketch the options you are weighing: a rear extension of one depth or another, a loft, a side return, or a combination. Each is set against the limits so you can see what it would involve.
It sits before the drawings for a reason. A full planning set is built around one decision. A study lets you make that decision with the facts, so the drawings are drawn once.
How much you can build without applying
The rules do the first sorting. A single-storey rear extension may go 3 metres from an attached house and 4 from a detached one without an application, and extensions and outbuildings together may cover no more than half the garden. A terrace house can add 40 cubic metres of roof under the loft rules; other houses can add 50.
Flats are different: householder permitted development does not apply to them at all, so a study for a flat starts from the position that anything external needs an application.
Rules that sit on top of the national ones
Councils add their own tests. Merton, for example, applies a 45 degree line from the neighbour's nearest habitable room window to limit how far a rear projection may go. Your borough may use a different test, and the study reads yours.
Where an option needs an application, the council's fee for a householder scheme is £548 from 1 April 2026, with a legal target of eight weeks to decide.
What happens after you choose
Once you have chosen, the study goes straight into the drawings: the survey, the plans and the elevations follow the same dimensions. If you have not decided, you can take the study to your builder or lender with the options priced against each other.
Compare it with the pre-purchase planning report if you have not yet bought the house, and read about the service on our feasibility study page.
Getting started
Send the address and the ideas, however rough. We confirm the fee and what the study will show.
The figures, with sources
3 m / 4 m
Reach of a single-storey rear extension without an application, on an attached house and a detached house.
Source: General Permitted Development Order 2015, Schedule 2, Part 1, Class A, checked 15 Oct 2026
Half
Largest share of the garden that other buildings and extensions may cover under permitted development.
Source: General Permitted Development Order 2015, Schedule 2, Part 1, Class A.1(b), checked 15 Oct 2026
40 m³
Extra roof volume a terrace house may add under the loft rules; 50 cubic metres for other houses.
Source: General Permitted Development Order 2015, Schedule 2, Part 1, Class B, checked 15 Oct 2026
45°
Line some councils draw from the neighbour's nearest habitable window to limit a rear projection.
Source: Merton Council, Small Sites Toolkit design guidance, checked 17 Oct 2026
£548
Charge by the council to decide a householder planning application from 1 April 2026.
Source: Ribble Valley Borough Council, national fee table from 1 April 2026, checked 17 Oct 2026
8 weeks
Statutory target for deciding a non-major planning application once valid.
Source: Development Management Procedure Order 2015, article 34, checked 15 Oct 2026
Art. 2(1)
A flat, or a building containing flats, has no householder permitted development to test.
Source: General Permitted Development Order 2015, article 2, checked 15 Oct 2026
Questions
Do I need a study if I already know what I want?
Not always. It earns its fee where you are choosing between options, or where you are not sure if the one you want is allowed.
Is the study credited against drawings?
We tell you in writing, before you commit, how the study fits with any drawings that follow.
Does it include a measured survey?
The study works from the house as it stands. If you want survey-accurate drawings, those come with our drawings services.
Will it tell me what the council will decide?
No one can promise that. It tells you what the rules allow and where an officer is likely to look hardest.
The fee for feasibility and options study
What you get
- Your house recorded as it stands
- Several options sketched and compared
- Each tested against the rules for your address
- Which options need an application and which do not
- A recommendation to take to your builder or lender
