Double-storey extensions
Side and rear extensions over two floors: a bigger kitchen below, a bedroom and bathroom above, tied into the existing roof so it looks like it was always there.
A double-storey extension costs less per square metre than a single-storey one, because the foundations and the roof are paid for once and serve two floors. It is also the job where the join shows if it is done badly: the ridge line, the brick or render match and the eaves detail are what the neighbours see for the next hundred years.
The roof is the job
We draw the new roof before anything else, because that is what planning officers look at and what decides whether the extension reads as part of the house. A hipped roof on a hipped house, a set-down ridge so the old and new do not have to line up to the millimetre, matched tiles from a reclamation yard where the originals are out of production.
Living through it
You stay in the house. The new rooms are built as a weathertight shell before we break through, so the dusty week comes late and short. Upstairs, we open into the existing landing on a single day and board it up again that evening.
What it costs
A 40 m² side extension over two floors, mid finish, is usually £100,000 to £125,000 including VAT, depending on the roof and how much of the existing house changes around it.
Finished jobs, with budgets
Common questions
Extensions
Do we need planning permission for a rear extension?
Often not. A single-storey rear extension up to 3 metres deep on a semi or terrace, or 4 metres on a detached house, is usually permitted development. We check at the first visit, and advise a lawful development certificate so a buyer’s solicitor never has to ask.
Can we live in the house while you build?
Almost everyone does. The new rooms are built outside first, so the old back wall comes out late and the dusty stretch is about a week. We help you set up a temporary kitchen for it.
What about the neighbours?
If you build on or near the boundary you need a party wall notice. We draft it for you and, if needed, recommend a surveyor. We also tell the neighbours the noisy dates a week ahead.
Other services
Get a fixed price for your double-storey extension
A free site visit, then a line-by-line written quote within five working days of the drawings. We are booking starts from March 2027. Site visits within 10 working days.