Thinking of a rear kitchen extension in Wirral or Liverpool? CNR Construction explains planning permission, costs, structural work, and design ideas to help you plan with confidence.
Do You Need Planning Permission?
Many rear extensions fall under Permitted Development rights, meaning no full planning application is needed. As a rule, a single-storey rear extension can extend up to 4 metres for a detached house, or 3 metres for a semi or terraced property, without permission.
A few exceptions to be aware of:
- Flats and maisonettes aren't covered by Permitted Development
- Conservation areas and listed buildings have stricter rules
- The extension can't cover more than half your garden
Not sure where you stand? CNR Construction can advise from the first consultation. We know the planning landscape across Wirral and Merseyside well.
How Much Does It Cost?
A rear kitchen extension involves foundations, structural work, brickwork, roofing, glazing, electrics, plumbing, and a full kitchen fit-out — so it's worth being realistic about budget from the start.
Small Extension (3m × 3m)
From £20,000–£30,000 for the build. A popular starting point for adding a functional kitchen-diner.
Medium Extension (3m × 4–5m)
Typically £35,000–£55,000. Enough space for a proper open-plan kitchen, dining, and family area.
Larger or Premium Spec
From £60,000–£90,000+. For larger footprints, higher-spec glazing, or more complex structural work.
Kitchen Fit-Out (on top)
From £5,000 for mid-range up to £30,000+ for bespoke cabinetry and appliances.
Build cost guide — Wirral area
£1,500–£2,500
per m² depending on specification and structural complexity. CNR Construction provides fully transparent, itemised quotes with no surprises.
Structural Work: What to Expect
Most rear kitchen extensions involve opening up the existing rear wall to connect the new space to your home. This typically means installing a steel RSJ beam to carry the load above — specialist work that requires Building Regulations approval.
Other structural elements commonly involved include load-bearing wall removal and beam installation, new foundations for the extension footprint, drainage adjustments if required, and insulation and damp proofing to current standards.
CNR Construction handles all of this in-house, including Building Regs sign-off, so you're not left coordinating multiple trades.
Design Ideas
Glazing
Bi-fold or sliding doors across the rear create a seamless connection to the garden, while a skylight or roof lantern floods the space with natural light. This is especially valuable on a north-facing plot where light is limited.
Open-Plan Layout
The most popular approach combines the kitchen with a dining and family area into one large social space. A well-placed island defines the cooking zone without closing off the room — and makes the extension feel considered rather than just bigger.
Kitchen Layout
More floor space means real layout flexibility. An L-shaped or U-shaped kitchen around an island maximises storage and workflow, and finally creates room for features older kitchens rarely allow: a proper pantry, a utility area, or a hob island with a ceiling extractor.
How Long Does It Take?
A standard 3m–4m extension typically takes 8–14 weeks on site. Larger or more complex projects run to 16–20 weeks. Allow additional time upfront for any planning or Building Regulations approvals.
Every client gets a clear timeline from the start, with regular updates throughout the build.
Why CNR Construction?
We're a Wirral-based team with 11+ years of experience and a 5-star Google rating. We manage every stage of your extension — from groundworks and structural work through to the finished kitchen — with transparent pricing and clear communication throughout.
Covering Wirral, Liverpool, Birkenhead, Heswall, Wallasey, West Kirby, Bebington, and surrounding areas. Get in touch to discuss your project.
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