FAQ
The questions everyone asks, answered properly.
Planning permission, costs, building regulations and timescales — without the jargon and without the vague non-answers.
01
Planning
Not always. Many single-storey rear extensions, loft conversions and garage conversions fall under permitted development, provided they meet size, height and materials limits — and provided your permitted development rights have not been removed. Flats, listed buildings and conservation areas are treated differently. We will tell you which route applies to your property at the consultation stage.
A householder planning application in London is usually determined in around eight weeks from validation, though busy boroughs can take longer. A lawful development certificate for permitted development work is typically eight weeks as well. Preparing drawings and supporting documents before submission normally takes three to six weeks.
It is a formal confirmation from the council that your project is permitted development and does not need planning permission. It is not compulsory, but it is strongly recommended — it protects you during the build and is regularly requested by buyers' solicitors when you come to sell.
Refusal is not the end of the project. We review the officer's reasons, and in most cases a revised scheme addressing those specific points can be resubmitted. Where the reasons are unreasonable, an appeal may be appropriate. We will always be honest about the likely outcome before you spend more money.
02
Costs
Build costs vary significantly by borough, specification and access. As a broad guide, London homeowners should currently budget from roughly £2,500 to £3,500 per square metre for a good-quality single-storey rear extension, before VAT, fees and fit-out. We will help you sanity-check your budget early rather than after the drawings are done.
Typical additional costs include design and planning drawings, building regulations drawings, structural calculations, planning application fees, building control fees and, where relevant, party wall surveyors. We set these out transparently so there are no surprises later in the process.
In much of London, well-designed additional space usually adds value — but the uplift depends heavily on the street, the property type and the quality of the finished work. We will give you a realistic view rather than an optimistic one.
03
Design & drawings
Depending on the stage: measured survey drawings of the existing property, proposed plans and elevations for planning, and a technical building regulations package for construction. Structural calculations are produced alongside by a structural engineer where the design requires them.
Yes. Design is a conversation. We expect to develop the scheme with you across a number of revisions before anything is submitted — it is far cheaper to change a drawing than a wall.
Where it helps you make a decision, yes. Seeing the space in three dimensions before committing to a build is often the difference between a design you like and a design you love.
04
Builders & engineers
Yes. We can introduce you to builders who have worked on comparable London projects and who are used to pricing from a complete drawing package. You remain in control — you appoint and contract with the builder directly.
Whenever you remove or alter load-bearing structure: opening up a rear wall, installing steel beams, forming a loft opening or building new foundations. Building control will require calculations before the work is signed off.
05
Timelines & consultations
It is a relaxed 30-minute conversation about your property, what you want to achieve and roughly what you want to spend. You will leave with a clear view of your likely planning route, realistic timescales and sensible next steps — whether or not you go on to work with us.
As a rough guide: two to four weeks for survey and design, eight weeks for a planning decision, then three to five weeks for building regulations and structural drawings. Many London homeowners are ready to start on site within four to five months of the first conversation.
Our focus is London and the surrounding home counties, where we know the boroughs and their local policies well. If you are just outside that area, get in touch and we will tell you honestly whether we are the right fit.
Next step
Still not sure where your project stands?
A free 30-minute consultation will answer the questions specific to your property — which is usually more useful than any FAQ page.