Part single, part two-storey extensions in Thornton-Cleveleys
Adding a part single, part two-storey extension in Thornton-Cleveleys gives you two new rooms stacked on one footprint. Here's how we'd approach it, what it typically costs and the rules that apply in England.
Thornton-Cleveleys: the key facts for this kind of project.
- Postcode districts
- FY5 and FY6
- County / area
- Lancashire, England
- Price region
- North West England
- Guide price
- £68,500–£94,000 (£1,900–£2,610 per m²)
- Approval route
- It may be permitted development if it goes no more than 3 m beyond the original rear wall (counting any single-storey part) and stays 7 m from the rear boundary; otherwise it needs planning permission.
- Nearest towns
- Cleveleys (0.8 miles), Poulton-le-Fylde (3.2 miles), Fleetwood (3.6 miles)
- Distance to Preston
- about 15.1 miles
- First visit
- Free, no obligation
About a part single, part two-storey extension
A part single, part two-storey extension is an extension where the ground floor is wider or deeper than the floor above, so only part of it rises to two storeys. It usually gives a large kitchen or living area with roof lights below and one bedroom or bathroom above. It is often a good way to add space while limiting the effect on neighbours.
Around Thornton-Cleveleys we also work in Cleveleys, Poulton-le-Fylde and Fleetwood, and across the rest of Lancashire. Postcode districts in and near Thornton-Cleveleys: FY5 and FY6.
What it costs in Thornton-Cleveleys
A guide price for Thornton-Cleveleys: around £68,500–£94,000 for a 6 m × 4 m ground floor and a first floor over half of it (36 m² in total). That works out at £1,900–£2,610 per m² of new floor space, including VAT at 20%. These are guides, not quotes. Ground conditions, steelwork and access can move the figure either way.
| Spec | Per m² | A 6 m × 4 m ground floor and a first floor over half of it (36 m² in total) |
|---|---|---|
| Essential | £1,750–£2,400 per m² | £63,000–£86,500 |
| Standard | £1,900–£2,610 per m² | £68,500–£94,000 |
| Premium | £2,280–£3,130 per m² | £82,000–£113,000 |
Planning and building regulations in Thornton-Cleveleys
In England, the extension can only be permitted development if it goes no more than 3 m beyond the original rear wall and stays at least 7 m from the rear boundary, with matching materials and roof pitch. We check the whole design against the rules, including the 50% garden coverage limit. If any part fails, or extends beyond a side wall on two floors, you need planning permission, costing £548 (or £575 for applications made from 8 December 2026).
Approval in England: Householder planning application: £548 (or £575 for applications made from 8 December 2026). Lawful development certificate: £274 (about £288 for applications from 8 December 2026). Councils should decide householder applications within 8 weeks of validation.
Building regulations: Building regulations approval (full plans recommended) from the council or a registered building control approver, with a completion certificate at the end.
Design points for Thornton-Cleveleys homes
Light into the kitchen
The single-storey part is the place for roof lights or a lantern, which bring daylight deep into the plan. In England, glazing is normally limited to 25% of the new floor area plus any windows removed, unless calculations show the house still performs, so we plan the balance early.
Structure at the step
The first-floor wall above often sits over the new open-plan space, so it needs a steel beam or frame to carry it. Loads come down at different points than in a full two-storey design, and the engineer sizes the foundations to suit each part.
How we'd run your project
Understand the brief
At your home in Thornton-Cleveleys we agree what you need: bedroom count, bathroom, kitchen space, and how much garden you want to keep.
Get it approved
Once you're happy with the design we submit it to the council for Thornton-Cleveleys and deal with any questions from the planning officer.
Detail and price
Construction drawings, engineer's calculations and building control sign-off, then a written fixed price for the build.
On site
One project lead runs the job, keeps you updated and arranges inspections at each stage until completion.
Questions about part single, part two-storey extensions in Thornton-Cleveleys
Which postcodes do you cover around Thornton-Cleveleys?
We cover Thornton-Cleveleys (FY5 and FY6) and nearby places including Cleveleys, Poulton-le-Fylde and Fleetwood, plus the rest of Lancashire. The first site visit is free.
How much does a part single, part two-storey extension cost in Thornton-Cleveleys?
Our guide for North West England, which covers Thornton-Cleveleys, is £1,900–£2,610 per m² including VAT. A typical project with a 6 m × 4 m ground floor and a first floor over half of it (36 m² in total) comes to about £68,500–£94,000. Design and approval fees are extra, and we fix the build price in writing once the design is agreed.
Who handles building regulations for a project in Thornton-Cleveleys?
We handle it as part of the project. What's needed in England: building regulations approval (full plans recommended) from the council or a registered building control approver, with a completion certificate at the end. We prepare the drawings and the engineer's calculations, book the inspections and pass you the completion paperwork at the end.
Can I add roof lights to the single-storey part?
Yes. Roof lights or a lantern over the single-storey part are one of the main reasons to choose this design, as they light the middle of a deep kitchen. In England they count towards the Part L glazing allowance, normally 25% of the new floor area plus windows removed, so we balance them with the rear doors.
Can the single-storey part be deeper than the two-storey part?
With planning permission, yes, and that is often the point of the design: the ground floor projects further into the garden while the first floor stays back from neighbours. Under permitted development, the depth limits for extensions of more than one storey can apply to the whole extension, so we confirm which route applies before drawings are finalised.
Nearby
Nearby towns we cover for part single, part two-storey extensions:
Other extensions in Thornton-Cleveleys
- Rear
- Side
- Wraparound
- Over a garage
- First floor
- Semi-detached
- Detached
- Kitchen and bedrooms
- Bedroom and en-suite
All two-storey extension services in Thornton-Cleveleys · Part single, part two-storey extensions across Lancashire
Ready to talk it through? Call us or send the form and we'll arrange a visit to your home in Thornton-Cleveleys.