Northumberland
Glazed and glass-box rear extensions in Northumberland
Full-height glass, slim frames and big rooflights for the most open rear room. Across Northumberland we handle the whole rear extension: survey, drawings, the planning route, building control and the build. Towns we cover here include Blyth, Cramlington and Ashington.
A wide sliding door with one long rooflight, rather than a fully glazed roof, keeps a glass-led extension usable in summer. Brick terraces, colliery houses and post-war semis make up much of Northumberland. Former mining areas often need a coal mining risk check before foundations are designed.
How much does a glazed rear extension cost in Northumberland?
For Northumberland we work from the North East England rate: £2,520–£4,320 per square metre of new floor, including VAT, standard specification. North East prices are among the lowest in our range; former mining ground is the main foundation variable.
| Size | Guide price inc VAT |
|---|---|
| 3 m wide × 4 m deep (12 m²) | £30,000–£52,000 |
| 4 m wide × 6 m deep (24 m²) | £60,500–£103,500 |
Your written price follows a measured survey and an agreed design, so it reflects your house, not an average.
Do you need planning permission in Northumberland?
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.
Where in Northumberland do we work?
FAQ
Questions people ask
Will a glass extension be too hot?
Not if it is designed for its orientation, with solar-control glass, shading and ventilation.
Is there a limit on how much glass I can have?
In England the simple rule is 25% of the floor area plus openings removed; more is allowed with a calculation showing the house still meets Part L.
Sliding or bifold doors?
Sliders give bigger panes and slimmer sightlines; bifolds open the whole width. Our guide compares them.
Do you cover all of Northumberland?
We cover 10 towns and districts in Northumberland, including Blyth, Cramlington and Ashington.
Who builds the extension?
Vetted building teams working under contract to us; your contract is with S&K Property Investments and Improvement Ltd.