High-quality, fully managed design & build across Cheshire — Alderley Edge, Wilmslow, Knutsford and Warrington.
How much does a house extension cost?
High-quality, fully managed design & build across Cheshire — Alderley Edge, Wilmslow, Knutsford and Warrington. Fully managed design & build across Cheshire and the wider North West.
A significant structural renovation of our downstairs — removing internal walls to create a large open-plan living space, a new downstairs WC, new flooring throughout, a brand-new kitchen and patio doors. The quality of workmanship has been outstanding and the project was completed within the agreed timescales. Any minor snags were dealt with promptly, often almost immediately.
We started 2025 with a 2-storey chimney being taken out. The lads did such a good job we gave them the rest of our renovation — two small extensions, a new downstairs toilet and kitchen, upstairs bathroom, a bedroom move and renovation, finishing with a full back garden renovation. We've had many comments on how good the work looks, especially the brickwork.
We've recently had a knock-through between the lounge and dining room along with other internal and brick work. We're extremely pleased with the quality — everything finished to a high standard, the team were professional, tidy and clearly took pride in what they were doing. Communication with Craig was great throughout and they stuck to the agreed timeline.
After getting a few quotes for our kitchen, we chose Cheshire Design & Build NW and I'm glad we did. They turned up when they said they would, kept us updated, and got on with the job without any fuss. The finished kitchen looks fantastic. Reliable, respectful, and they clearly take pride in their work.
Excellent. Craig replied immediately and viewed the job. A detailed price and timeline was sent. Once the job was underway problems occurred — not Craig's fault — new plans were made and the job was done. Communication was 100%, that's important for me, and a cleaner is sent in at the end of the work. A great job done. Would definitely recommend.
Brilliant company, amazing team. Came to fit a lintel for me and brick up the outside of the house. The job was finished quickly and efficiently — very friendly and knowledgeable. Thank you so much, highly recommend.
This company has been the best to work with in terms of professionalism and quality — not like other companies I have worked with in the past. 10/10 service 👍
Highly recommend! Craig was very reliable and the quality of workmanship was outstanding! Thank you!
Great lads, very polite, showed up on time and did a great job.
A significant structural renovation of our downstairs — removing internal walls to create a large open-plan living space, a new downstairs WC, new flooring throughout, a brand-new kitchen and patio doors. The quality of workmanship has been outstanding and the project was completed within the agreed timescales. Any minor snags were dealt with promptly, often almost immediately.
We started 2025 with a 2-storey chimney being taken out. The lads did such a good job we gave them the rest of our renovation — two small extensions, a new downstairs toilet and kitchen, upstairs bathroom, a bedroom move and renovation, finishing with a full back garden renovation. We've had many comments on how good the work looks, especially the brickwork.
We've recently had a knock-through between the lounge and dining room along with other internal and brick work. We're extremely pleased with the quality — everything finished to a high standard, the team were professional, tidy and clearly took pride in what they were doing. Communication with Craig was great throughout and they stuck to the agreed timeline.
After getting a few quotes for our kitchen, we chose Cheshire Design & Build NW and I'm glad we did. They turned up when they said they would, kept us updated, and got on with the job without any fuss. The finished kitchen looks fantastic. Reliable, respectful, and they clearly take pride in their work.
Excellent. Craig replied immediately and viewed the job. A detailed price and timeline was sent. Once the job was underway problems occurred — not Craig's fault — new plans were made and the job was done. Communication was 100%, that's important for me, and a cleaner is sent in at the end of the work. A great job done. Would definitely recommend.
Brilliant company, amazing team. Came to fit a lintel for me and brick up the outside of the house. The job was finished quickly and efficiently — very friendly and knowledgeable. Thank you so much, highly recommend.
This company has been the best to work with in terms of professionalism and quality — not like other companies I have worked with in the past. 10/10 service 👍
Highly recommend! Craig was very reliable and the quality of workmanship was outstanding! Thank you!
Great lads, very polite, showed up on time and did a great job.
The per-square-metre figure is a trap
Every extension article gives you a rate per square metre. The problem is that two extensions of identical size can differ enormously in cost — because the cost isn't in the floor area, it's in the foundations, the structure, the glazing and the roof.
Here's what actually moves the number.
What drives the cost of an extension
- Single or double storey — a second storey adds structure, roof and internal reconfiguration, not just floor area.
- Foundations and ground — trees, clay, sloping ground and existing drains all change the foundation design. This is the biggest hidden variable.
- Structural openings — how much of the existing house opens into the new space, and how big the steels have to be.
- Roof type — a warm flat roof, a pitched tiled roof and a lantern-lit flat roof are very different builds.
- Glazing — bi-folds, sliders and rooflights are one of the biggest single swings in the budget.
- External finish — matching brick, reclaimed brick, render or cladding.
- Internal fit-out — whether the new space is a shell to decorate or a finished kitchen with underfloor heating.
- Planning — permitted development versus a full householder application.
- Access — whether machinery can reach the site or everything is barrowed through the house.
How we price it
After a free site visit we produce a fully itemised written quotation — materials, labour, prelims and contingency broken out separately, with a clear programme. No fixed per-metre rate, no hidden costs, and nothing that only appears once the scaffold is up.
See our house extensions service — or kitchen extension costs and loft conversion costs.
Benefits of House Extension Cost
How We Handle House Extension Cost
Consultation
An initial conversation about your project — scope, brief, budget framing, and the outcome you want.
Site Visit
We come to the property to understand the existing space, take measurements, and discuss feasibility on the ground.
Quotation
A detailed written quotation covering every element of the work, with no hidden costs.
Design & Planning
Where required, we handle architectural drawings, planning permission, and Building Regulations in-house.
Full Project Delivery
Our long-standing in-house team — supported by trusted specialist subcontractors — delivers the entire build.
Completion
Final walk-through, sign-off, and your workmanship guarantee.
Ready for House Extension Cost?
Get in touch for a free, no-obligation site visit and a detailed written quotation. Cheshire-led, with Greater Manchester covered for the right projects.
House Extension Cost FAQs
Why don't you publish a cost per square metre?
Because two extensions of the same size can cost very differently. The money is in the foundations, the structural openings, the glazing and the roof — not the floor area. A per-m² rate produces a number that feels precise and isn't.
What's the biggest hidden cost on an extension?
Foundations. Trees, clay, sloping ground or a drain running where you want to build can all change the foundation design significantly — and none of it is visible until someone surveys the site properly. That's exactly what the free site visit is for.
Do I need planning permission, and does that change the cost?
Many single-storey rear extensions fall under permitted development, which is cheaper and faster than a full householder application. We check which route yours takes at the site visit and handle the application either way.
Is the quotation free?
Yes — the site visit and the detailed written quotation are free and carry no obligation.