Knaresborough, North Yorkshire
Semi-detached rear extension in Knaresborough
For homes in Knaresborough, a semi-detached rear extension is often the simplest way to gain space without moving. Single or two-storey extensions for semi-detached houses, with side access and one party wall. We take it from survey to completion certificate.
Knaresborough and its postcode districts HG5 are part of our North Yorkshire coverage. Where a Knaresborough semi already has a small lean-to at the back, we usually replace it rather than extend it.
Book a free site visit
Tell us about the house and we'll call to arrange a free, no-obligation visit.
How much does a semi-detached rear extension cost in Knaresborough?
Guide prices for a semi-detached rear extension in Knaresborough start from our Yorkshire and the Humber rate of £1,770–£2,880 per square metre, including VAT. Yorkshire prices sit below our West Midlands baseline; matching natural stone is the main variable.
| Size | Guide price inc VAT |
|---|---|
| 3 m wide × 4 m deep (12 m²) | £21,000–£34,500 |
| 4 m wide × 5 m deep (20 m²) | £35,500–£57,500 |
| 4 m wide × 6 m deep (24 m²) | £42,500–£69,000 |
These are guide ranges; the written quote after the survey is the figure that counts.
Do you need planning permission for a semi-detached rear extension in Knaresborough?
Whether your semi-detached rear extension in Knaresborough needs a planning application depends on its size, your house and any local restrictions.
In England a single-storey rear extension can often be built under permitted development: up to 3 metres beyond the original rear wall of an attached house, or 4 metres on a detached house, no higher than 4 metres, with eaves no higher than 3 metres if any part is within 2 metres of a boundary.
England's rules allow a rear extension of more than one storey without an application only when it is no deeper than 3 metres and at least 7 metres from the boundary opposite the rear wall, and never on designated land. Most two-storey schemes need householder planning permission.
England also has the larger home extension route: a single-storey rear extension of up to 6 metres on an attached house or 8 metres on a detached house, after prior approval from the council. The council notifies your neighbours and has 42 days to decide; the fee is £249 (£310 for applications made from 8 December 2026). The route is not available on designated land such as conservation areas.
Conservation areas, National Parks, National Landscapes and the Broads restrict permitted development, and listed buildings always need listed building consent. We check your house's planning history and any conservation area before drawing, so the route is clear before you spend on plans.
What are homes in Knaresborough like to extend?
Knaresborough has through terraces and some back-to-backs as well as later semis; back-to-backs have little or no rear space, so we look at side or loft options there.
How a semi-detached rear extension in Knaresborough comes together
Survey visit
We visit free of charge, measure up, check access, drainage and neighbours' extensions, and note what you want the room to do.
Options and costs
We draw layout options and price each one, so the budget shapes the design rather than surprising you later.
Approvals
Permitted development check, prior approval or planning application, then Building Regulations drawings and structural calculations, plus party wall notices where they apply.
Build and sign-off
We build to the approved drawings with regular updates, then hand over the building control completion certificate and any guarantees from suppliers.
Semi-detached rear extensions near Knaresborough
Close by, we work in Harrogate, about 3.1 miles away, and Wetherby, about 6.5 miles away.
- Semi-detached rear extension in Harrogate
- Semi-detached rear extension in Wetherby
- Semi-detached rear extension in Ripon
- Semi-detached rear extension in Otley
- Semi-detached rear extension in Chapel Allerton
Other work in Knaresborough:
FAQ
Semi-detached rear extension questions in Knaresborough
Do you handle building control in Knaresborough?
Yes. We apply to the council or a registered building control approver and hand over the completion certificate.
Will I need a structural engineer?
Yes for the beam over the new opening and usually the foundations; we arrange them and their calculations go to building control.
Do I need a party wall agreement?
Usually with the attached neighbour, in England and Wales.
How long does a rear extension take to build in Knaresborough?
Most single-storey rear extensions take 10 to 16 weeks on site and two-storey extensions 16 to 26 weeks, after design and approvals.
Can I get a price without a visit?
Our online guide-price tool gives a range in a couple of minutes. A written price needs a survey.
Do I need planning permission for a rear extension in Knaresborough?
Often not for a single-storey rear extension of up to 3 metres (4 metres on a detached house) under permitted development, or up to 6 or 8 metres with prior approval, unless the house is in a conservation area or its rights have been removed.