Part single, part two-storey extensions in Knottingley
Adding a part single, part two-storey extension in Knottingley 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.
Before you start in Knottingley, here's what applies.
- Postcode districts
- WF11
- County / area
- West Yorkshire, England
- Price region
- Yorkshire and the Humber
- Guide price
- £66,000–£91,000 (£1,840–£2,530 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
- Pontefract (2.6 miles), Castleford (4.5 miles), Featherstone (West Yorkshire) (4.6 miles)
- Distance to Leeds
- about 13.4 miles
- First visit
- Free, no obligation
About a part single, part two-storey extension
A part single, part two-storey extension suits you if you want a generous ground floor but only need one extra room upstairs, or if a full two-storey design would affect a neighbour too much. You get design options that test where the two-storey part works best, the approvals your nation needs, structural design, building regulations approval and the build, carried out by vetted teams working under S&K.
We cover postcode district WF11 in and around Knottingley, along with neighbouring Pontefract, Castleford and Featherstone (West Yorkshire).
What it costs in Knottingley
Expect a part single, part two-storey extension in Knottingley to land somewhere around £66,000–£91,000 for a 6 m × 4 m ground floor and a first floor over half of it (36 m² in total). Our Yorkshire and the Humber guide rate is £1,840–£2,530 per m², including VAT. Professional fees for drawings and the structural engineer are listed separately on our prices page.
| Spec | Per m² | A 6 m × 4 m ground floor and a first floor over half of it (36 m² in total) |
|---|---|---|
| Essential | £1,690–£2,330 per m² | £61,000–£84,000 |
| Standard | £1,840–£2,530 per m² | £66,000–£91,000 |
| Premium | £2,210–£3,040 per m² | £79,500–£109,500 |
Planning and building regulations in Knottingley
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 Knottingley homes
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.
The roof junction
Where the single-storey roof meets the two-storey wall you need a sound weathering detail, usually a lead or similar flashing, and enough height for roof lights or a lantern. We set the roof falls and the upstairs window sill heights together so they do not clash.
How we'd run your project
Look at the house
We start in Knottingley with a free visit: measurements, photos, a look at the loft and drains, and a frank chat about budget.
Plans, then approval
Measured survey, design, then the right approval route for your house. We explain each step before we take it.
Detail and price
Construction drawings, engineer's calculations and building control sign-off, then a written fixed price for the build.
Build and sign-off
Vetted teams working under S&K build the extension, and we arrange the building control completion certificate at the end.
Questions about part single, part two-storey extensions in Knottingley
How long does a part single, part two-storey extension take?
Allow 4 to 8 weeks for survey and design, then the approval period (councils should decide householder applications within 8 weeks of validation), then 4 to 8 weeks of technical design, which can overlap. The build itself usually takes 14 to 20 weeks, longer for large or complex designs.
Do I need planning permission for a part single, part two-storey extension in Knottingley?
Knottingley is in England, so England planning rules apply. 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. If in doubt, a lawful development certificate or a planning application gives you certainty before you build.
How much does a part single, part two-storey extension cost in Knottingley?
Our guide for Yorkshire and the Humber, which covers Knottingley, is £1,840–£2,530 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 £66,000–£91,000. Design and approval fees are extra, and we fix the build price in writing once the design is agreed.
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
Other towns near Knottingley:
Other extensions in Knottingley
- Rear
- Side
- Wraparound
- Over a garage
- First floor
- Semi-detached
- Detached
- Kitchen and bedrooms
- Bedroom and en-suite
All two-storey extension services in Knottingley · Part single, part two-storey extensions across West Yorkshire
The quickest next step is a visit. We'll look at your house in Knottingley and give you an honest view of the options.