Blackburn, Lancashire
Two-storey rear extension in Blackburn
A larger kitchen downstairs and an extra bedroom or bathroom upstairs, under one roof. We design, get the approvals for and build two-storey rear extensions in Blackburn and the surrounding area, with one contract from the first survey to building control sign-off.
Blackburn and its postcode districts BB1, BB2 and BB3 are part of our Lancashire coverage. In Blackburn, a two-storey rear extension is worth comparing with the cost of moving once stamp duty, agents' and legal fees are counted.
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 two-storey rear extension cost in Blackburn?
A two-storey rear extension in Blackburn is priced at £1,690–£2,540 per square metre including VAT as a guide, before kitchen fit-out and fees. North West prices sit below our West Midlands baseline; access on terraced streets is the main variable.
| Size | Guide price inc VAT |
|---|---|
| 3 m × 5 m footprint, two floors (30 m²) | £51,000–£76,000 |
| 4 m × 6 m footprint, two floors (48 m²) | £81,000–£122,000 |
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 two-storey rear extension in Blackburn?
The planning route for a two-storey rear extension in Blackburn is set by England's householder rules and your council.
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.
Conservation areas, National Parks, National Landscapes and the Broads restrict permitted development, and listed buildings always need listed building consent. Before any drawing we look up the property's history with the council, because earlier extensions and removed rights change the answer.
What are homes in Blackburn like to extend?
Blackburn has long runs of terraced houses with back yards and alleys, plus 1930s semis further out. Yard extensions on terraces are often single-storey and close to both boundaries.
How a two-storey rear extension in Blackburn comes together
Free site visit
We measure the house and garden, look at the back wall, drainage and boundaries, and talk through what you want from the space.
Drawings and budget
Floor plans and elevations for the options, each with a guide price.
Planning and regulations
We take the design through the right planning route, then produce the construction drawings and engineer's calculations for building control.
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.
Two-storey rear extensions near Blackburn
Close by, we work in Darwen, about 3.7 miles away, and Great Harwood, about 3.9 miles away.
- Two-storey rear extension in Darwen
- Two-storey rear extension in Great Harwood
- Two-storey rear extension in Accrington
- Two-storey rear extension in Haslingden
- Two-storey rear extension in Padiham
Other work in Blackburn:
FAQ
Two-storey rear extension questions in Blackburn
Do you handle building control in Blackburn?
Yes. We apply to the council or a registered building control approver and hand over the completion certificate.
Do I need a party wall agreement?
In England, usually yes if the extension is on or near a shared boundary or the foundations are close to a neighbour's building. We serve the notices.
What is the 45-degree rule?
Many councils check that a two-storey extension does not cross a 45-degree line drawn from the nearest habitable window of the neighbouring house. We test it at the first drawing.
Can I live at home while the extension is built?
Usually yes. Most of the work is outside until the back wall is opened near the end, and that stage is screened off.
What postcode areas do you cover around Blackburn?
Including BB1, BB2 and BB3, and the surrounding Lancashire area.
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.