Double-storey extensions across Lancaster
Thinking about a double-storey extension for your Lancaster home? Start with a free site visit: we measure up, check what the council will allow and give you honest guide figures on the day.
- Guide price in LancasterFrom £36,000 inc VAT
- PlanningUsually a householder application
- Build time16–24 weeks on site
- Postcode districtsLA1, LA4
Covering Lancaster
Across LA1, LA4, we can visit, measure and advise. We also work in nearby Morecambe (3 miles), Fleetwood (12 miles), Thornton-Cleveleys (15 miles), Poulton-le-Fylde (17 miles).
Just over the Cumbria border, Ulverston is about 16 miles away. Across the North West, terraced houses with small rear yards suit compact rear and side return extensions, while suburban semis have room for more.
Who a double-storey extension suits
- Growing families who need a bedroom as well as a bigger kitchen
- Houses with enough distance to the rear or side boundary
- Homeowners who would otherwise consider moving
Planning rules that apply in Lancaster
In England a two-storey rear extension is permitted development only if it projects no more than 3 m from the original rear wall, sits at least 7 m from the rear boundary, matches the roof pitch and uses obscure, non-opening side windows upstairs. Most two-storey extensions therefore go through a householder planning application, which costs £548 from 1 April 2026 and normally takes about 8 weeks.
The planning position for a specific Lancaster address depends on its history and any designations, which is why we check it at the first visit.
If the work involves a shared wall, building on the boundary, or digging foundations within 3 m (sometimes 6 m) of a neighbour's building, the Party Wall etc. Act 1996 applies and notice must be served before work starts: two months for work to a party wall, one month for new walls on the boundary and for excavations.
Building regulations approval is separate from planning. In England you can use the council's building control team or a registered building control approver; a full plans application gets the drawings checked before work starts, and the inspector signs the work off with a completion certificate.
Applications are decided by the local planning authority (your district, borough or unitary council).
How much does a double-storey extension cost in Lancaster?
These guide figures apply our North West England adjustment (×0.95) to national rates. They include VAT at 20% and cover the build itself; design and council fees are listed separately.
Typical rates in Lancaster: £1,470 to £2,850 per m² including VAT, depending on specification.
| Size | Essential | Standard | Premium |
|---|---|---|---|
| 3 m × 4 m, two floors 24 m² | £36,000 – £43,500 | £41,000 – £54,000 | £52,000 – £68,500 |
| 4 m × 4 m, two floors 32 m² | £47,000 – £56,500 | £54,500 – £71,500 | £69,500 – £91,500 |
| 4 m × 6 m, two floors 48 m² | £70,500 – £84,500 | £82,000 – £107,500 | £104,500 – £137,000 |
For a figure based on your own dimensions, use our guide-price tool.
From first visit to completion
Site visits are free and there is no obligation. Where drawings are needed, the design stage is priced in writing before it starts.
Free site visit
First, a site visit: we look at the house, garden, access and drains and listen to what you need.
Design and approvals
Once the layout is agreed, we deal with the council: planning permission or written confirmation that none is needed, plus building control.
Fixed written price
We confirm the build price in writing, based on the approved drawings and the finishes you have chosen.
Build and sign-off
The build is managed from start to finish, inspected at each stage and signed off on completion.
Your questions about a double-storey extension in Lancaster
Do you cover all of Lancaster?
Yes. We cover Lancaster and the surrounding parts of Lancashire. Site visits are free and there is no obligation.
Can I see a price before committing to anything?
Yes. The guide prices on this page are adjusted for Lancaster, and the guide-price tool gives a range for your own size. After the survey you get a written price before anything is agreed.
Do I need building regulations approval in Lancaster?
Yes. Almost every extension needs it, whatever the planning route. We prepare the drawings and book the inspections.
Does a double-storey extension need planning permission?
Often, yes. In England a two-storey rear extension can be permitted development only if it projects no more than 3 m and sits at least 7 m from the rear boundary, with matching roof pitch and obscure side windows. Side extensions over one storey always need planning permission. We confirm the route at the survey.
Is a two-storey extension cheaper per square metre?
Usually. Our guide range is about £1,470 to £2,850 per m² of new floor area including VAT, compared with £1,660 to £3,230 per m² for single-storey work, because the foundations and roof are shared across two floors.
Book a free site visit in Lancaster
We will measure up, check the planning position and give you honest guide figures.
- Free, no-obligation site visit
- Planning route checked before you spend on drawings
- Written price once the design is agreed
- Building control sign-off at the end
Prefer to talk? Call 0800 088 6341 or .
Book a free site visit
Tell us a little about the project and we will arrange a time.