Single-storey rear extensions in Washington
Thinking about a single-storey extension for your Washington 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 WashingtonFrom £19,000 inc VAT
- PlanningOften permitted development (3–4 m), or prior approval up to 6–8 m
- Build time10–16 weeks on site
- Postcode districtsDH4, NE9, NE10, NE37, NE38
Single-storey extension prices in Washington
Labour and material costs vary across the UK, so for Washington we use our North East England factor (×0.91). The ranges include VAT and exclude design, structural and council fees.
Typical rates in Washington: £1,590 to £3,090 per m² including VAT, depending on specification.
| Size | Essential | Standard | Premium |
|---|---|---|---|
| 3 m × 4 m 12 m² | £19,000 – £22,500 | £22,000 – £28,500 | £28,000 – £37,500 |
| 4 m × 5 m 20 m² | £31,500 – £37,500 | £37,000 – £47,500 | £47,000 – £62,000 |
| 5 m × 6 m 30 m² | £47,500 – £56,000 | £55,500 – £71,000 | £70,500 – £93,000 |
Try the guide-price tool to see a range for your own size and finish.
Do I need planning permission in Washington?
In England a single-storey rear extension can usually go up to 3 m beyond the original rear wall of a semi-detached or terraced house, or 4 m on a detached house, without a planning application, provided it is no more than 4 m high, keeps eaves to 3 m within 2 m of a boundary and, with other buildings, covers no more than half the land around the original house. The larger home extension prior approval scheme raises those depths to 6 m and 8 m, with neighbours notified and a 42-day decision.
The planning position for a specific Washington 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).
What is included
- Foundations, drainage and groundworks
- Walls, steel beams and the new opening into the house
- Measured survey and design
- Doors, windows, insulation, plastering and first fix to finish
- Building regulations drawings and structural calculations
Depth is the big decision. Every extra metre adds floor area but also takes garden and can push you out of permitted development. We draw the room at two or three depths so you can see the trade-off in space, light and cost before anything is fixed.
Covering Washington
Across DH4, NE9, NE10, NE37, NE38, SR4, we can visit, measure and advise. The same team covers Felling (4 miles), Houghton-le-Spring (5 miles), Hebburn (5 miles), Sunderland (5 miles), all within easy reach.
For homes towards County Durham, Chester-le-Street is around 4 miles away. Across the North East, houses often have rear yards or modest gardens, so compact, well-lit single-storey extensions make the biggest difference.
What happens next
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
It starts with a visit to your house to measure, check access and talk through ideas and budget.
Design and approvals
Drawings are prepared and agreed with you, then submitted for the right planning route and building regulations approval.
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
Our team builds the extension, keeps you updated weekly and finishes with building control sign-off.
Questions people ask about single-storey extensions
Will my neighbours in Washington be involved?
If a planning application or prior approval is needed, the council notifies neighbours. If the work is on or near a shared boundary, party wall notices may also be needed.
Do you cover all of Washington?
Yes. We cover Washington and the surrounding parts of Tyne and Wear. 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 Washington, and the guide-price tool gives a range for your own size. After the survey you get a written price before anything is agreed.
How much does a single-storey extension cost per square metre?
Our guide range is about £1,590 to £3,090 per m² including VAT, depending on specification. A standard-spec 4 m × 5 m room usually lands at £37,000 to £47,500 in Washington, plus design and council fees.
How deep can a single-storey rear extension be without planning permission?
In England, up to 3 m beyond the original rear wall on a semi-detached or terraced house and 4 m on a detached house, within height and boundary limits. Through the larger home extension prior approval scheme those depths rise to 6 m and 8 m. Wales, Scotland and Northern Ireland use their own rules, which we check for your address.
Book a free site visit in Washington
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.