A double-storey extension adds two floors of new space to your house in one build, typically a larger kitchen or living room downstairs with an extra bedroom, bathroom or en-suite above, sharing one set of foundations and one roof.
Northumberland is part of our UK-wide coverage for a double-storey extension. Places we cover include Blyth, Cramlington, Ashington and Bedlington, and we travel to smaller communities across the area as well. Since your property is in England, the relevant planning and building rules are the ones set there. In the North East, budget around £54,000–£108,000 with VAT; the figure is confirmed after a survey that costs you nothing.
- Guide price
- £54,000–£108,000 inc VAT
- Time on site
- 14–22 weeks on site
- Planning rules
- England
- Price level
- About 10% below the national guide
- Towns listed
- 4
- Survey
- Free, with a written quote
How much does a double-storey extension cost in Northumberland?
Below is a breakdown of typical costs for a double-storey extension in Northumberland. Because rates in the North East are about 10% below the national guide, the overall guide comes to £54,000–£108,000, including VAT. Size, materials and access move the figure, and a free-of-charge survey settles it.
| Type of job | What it usually involves | Guide in Northumberland |
|---|---|---|
| Small (15–20m² total) | A compact rear or side extension adding a small room on each floor. | £36,000–£58,000 |
| Typical (30–40m² total) | A larger kitchen or living room below with a double bedroom or en-suite above. | £54,000–£108,000 |
| Large (50m² plus total) | Wide or deep extensions, often with a new bathroom, steelwork and high-spec glazing. | £90,000–£162,000 |
What moves the price up or down:
- How the new roof joins the existing roof
- Bathrooms, en-suites and plumbing on the upper floor
- Foundation depth, ground conditions and drains to divert
- Scaffolding duration, access and the level of finishes
What do you get?
- Groundworks, foundations and below-ground drainage
- First-floor joists, stud walls and new openings upstairs
- Roof structure tied into the existing roof, tiled to match
- Scaffolding for the full build, erected and inspected
- Electrics, plumbing and heating by qualified trades, with certificates
- Windows, external doors, plastering and internal doors
Homes in Northumberland
Stone dominates rural Northumberland, from sandstone farmhouses and villages to fortified bastle houses in the uplands. Alnwick, Hexham and Morpeth have historic stone centres, Berwick has Georgian streets, and south-east towns such as Ashington, Blyth and Bedlington have colliery terraces. Cramlington grew from the 1960s with planned estates.
Stone homes often need lime pointing, roof slating and breathable render. Colliery terraces suit loft conversions and rear extensions, and estate homes commonly take garage conversions and window upgrades.
The coast is exposed to cold North Sea winds, and the Cheviots and higher moorland see snow and hard frosts in winter.
Planning and building rules in Northumberland
Northumberland is in England, so the planning and building rules set out below are the ones that apply. We confirm the details with the council before we quote.
In England, a two-storey rear extension can only be permitted development if it is no more than 3 m deep, at least 7 m from the rear boundary and finished to match the house. Most double-storey and all two-storey side extensions need full planning permission.
Building Regulations approval is needed, with structural calculations for beams, foundations and the roof. The Party Wall etc. Act 1996 often applies on semi-detached and terraced houses.
Rules change and every property is different, so we check the planning history and constraints for your address before we quote.
How does the job run?
Survey and measure
First, someone visits your home in Northumberland to see the space, take measurements and note anything that could affect the work, such as access or the condition of what is there. There is no charge for this visit.
Your fixed price
Next you receive a written quote with a fixed price for the agreed specification. It lists what is included, what is not, and how payments are staged, so you can compare it properly.
Plan and prepare
We handle the paperwork side: checking whether planning permission or building control approval is needed, submitting applications where they are, and scheduling the trades and materials around your dates.
Finish and handover
Our trades complete a double-storey extension while your point of contact keeps you updated. When everything is finished, we clear the site, take away waste and go through the result with you before handover.
How we work
Questions about a double-storey extension in Northumberland
Can the new upstairs room have its own bathroom?
A new upstairs room can usually have an en-suite, provided waste pipes can reach the soil stack or a new one can be installed. Running the waste pipe to the right falls is the main design question, and a pumped system is an option where gravity will not work. We plan bathroom positions at the design stage so pipes, ventilation and insulation are built in rather than added later.
How long does a double-storey extension take?
A double-storey extension typically takes 14–22 weeks on site, depending on size, roof design and weather. Foundations and ground-floor walls come first, then the first-floor joists, upper walls and roof. Once it is weathertight, electrics, plumbing, plastering and finishes follow. Allow extra time beforehand for drawings, calculations and approvals. We give you a stage-by-stage programme with your quote.
Do I need planning permission in Northumberland?
It depends on the work, the size of the project, your property type and whether the building is listed or in a conservation area. Northumberland is in England, so England's rules apply. Many smaller jobs need no planning application, but some still need building control approval. We check what applies to your address before quoting.
How much will a double-storey extension cost in Northumberland?
As a guide, expect to pay £54,000–£108,000 including VAT for a double-storey extension in Northumberland. That range is adjusted for the North East, which runs about 10% below the national guide. Where your project lands depends on size, materials, access and the condition of what is already there. We confirm a fixed price in writing after a free survey of your home.
Is a double-storey extension better value than single-storey?
A double-storey extension usually gives better value per square metre than a single-storey one, because the same foundations and roof serve twice the floor area. The overall cost is higher, and planning can be harder because of the effect on neighbours. If you might want an extra bedroom later, building both floors now avoids a second round of disruption and scaffolding.
Towns in Northumberland
We offer a double-storey extension in each of the towns below, all within Northumberland. Select yours for guide prices, postcodes covered and nearby places.