Darwen, Lancashire
Glazed rear extension in Darwen
Glazed rear extension in Darwen: full-height glass, slim frames and big rooflights for the most open rear room. We measure the house, show you what the rules allow, price it in writing and build it.
We cover Darwen (BB1, BB2 and BB3) as part of our Lancashire work. A wide sliding door with one long rooflight, rather than a fully glazed roof, keeps a glass-led extension usable in summer.
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 glazed rear extension cost in Darwen?
For Darwen we work from the North West England rate: £2,630–£4,510 per square metre of new floor, including VAT, standard specification. 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) | £31,500–£54,000 |
| 4 m wide × 6 m deep (24 m²) | £63,000–£108,500 |
We put a fixed price in writing once the design is agreed, and explain any provisional sums such as foundations.
Do you need planning permission for a glazed rear extension in Darwen?
The planning route for a glazed rear extension in Darwen is set by England's householder rules and your council.
Under England's householder permitted development rules you can usually add 3 metres at the back of an attached house, or 4 metres on a detached house, without a planning application, as long as the extension stays under 4 metres high and its eaves stay under 3 metres where it is within 2 metres of a boundary.
New fabric must meet Approved Document L (2021 edition incorporating 2023 amendments): walls 0.18, roof 0.15 and floor 0.18 W/m²K, windows 1.4 W/m²K or Band B. Under the simple route, new windows, doors and rooflights should not exceed 25% of the extension floor area plus any openings removed; more glass is possible with a whole-house calculation.
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 Darwen like to extend?
Darwen 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 glazed rear extension in Darwen 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.
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.
Glazed rear extensions near Darwen
From Darwen, the nearest places we also cover are Blackburn (3.7 miles) and Haslingden (5.8 miles).
- Glazed rear extension in Blackburn
- Glazed rear extension in Haslingden
- Glazed rear extension in Accrington
- Glazed rear extension in Great Harwood
- Glazed rear extension in Ramsbottom
Other work in Darwen:
FAQ
Glazed rear extension questions in Darwen
What postcode areas do you cover around Darwen?
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.
Sliding or bifold doors?
Sliders give bigger panes and slimmer sightlines; bifolds open the whole width. Our guide compares them.
How long does a rear extension take to build in Darwen?
Most single-storey rear extensions take 10 to 16 weeks on site and two-storey extensions 16 to 26 weeks, after design and approvals.
How much does a glazed rear extension cost in Darwen?
As a guide, £2,630–£4,510 per square metre including VAT for a standard specification. For example, 3 m wide × 4 m deep (12 m²): about £31,500–£54,000 at that rate. Your written price follows the survey.
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.