Lancaster, Lancashire
Semi-detached rear extension in Lancaster
Thinking about a semi-detached rear extension in Lancaster? Single or two-storey extensions for semi-detached houses, with side access and one party wall. Our team handles the drawings, the planning route and the build, and your contract is with one company throughout.
Lancaster is covered from our Lancashire round, including LA1, LA3 and LA4. Where a Lancaster 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 Lancaster?
Guide prices for a semi-detached rear extension in Lancaster start from our North West England rate of £1,790–£2,910 per square metre, including VAT. North West prices sit below our West Midlands baseline; access on terraced streets is the main variable.
| Size | Guide price inc VAT |
|---|---|
| 3 m wide × 4 m deep (12 m²) | £21,500–£35,000 |
| 4 m wide × 5 m deep (20 m²) | £35,500–£58,500 |
| 4 m wide × 6 m deep (24 m²) | £43,000–£70,000 |
Ground conditions, glazing, the roof and how far the house is opened up move the final figure within the range.
Do you need planning permission for a semi-detached rear extension in Lancaster?
Whether your semi-detached rear extension in Lancaster needs a planning application depends on its size, your house and any local restrictions.
English permitted development (Class A) allows a single-storey rear extension of 3 metres on a terraced or semi-detached house and 4 metres on a detached one, measured from the original house, with a maximum height of 4 metres and eaves of no more than 3 metres 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 Lancaster like to extend?
Stone and brick terraces are common around Lancaster. Where houses back onto a ginnel or alley, deliveries can come in from the rear, which makes the build tidier. In Lancaster we measure the attached neighbour's extension at the survey, because it often sets the sensible depth for yours.
How a semi-detached rear extension in Lancaster comes together
Look round and measure
A free visit to see the back of the house, measure it, check the drains and boundaries and hear what you need.
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.
Fixed price and build
A written price for the agreed design, a start date and a named contact through the build, ending with the building control completion certificate.
Semi-detached rear extensions near Lancaster
From Lancaster, the nearest places we also cover are Morecambe (2.9 miles) and Heysham (3.8 miles).
- Semi-detached rear extension in Morecambe
- Semi-detached rear extension in Heysham
- Semi-detached rear extension in Fleetwood
- Semi-detached rear extension in Thornton-Cleveleys
- Semi-detached rear extension in Cleveleys
Other work in Lancaster:
FAQ
Semi-detached rear extension questions in Lancaster
Do you handle building control in Lancaster?
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.
Is the site visit in Lancaster free?
Yes. We visit, measure up and talk through the options with no cost and no obligation.
How long does a rear extension take to build in Lancaster?
Most single-storey rear extensions take 10 to 16 weeks on site and two-storey extensions 16 to 26 weeks, after design and approvals.
What postcode areas do you cover around Lancaster?
Including LA1, LA3 and LA4, and the surrounding Lancashire area.