What is a double-storey extension?
A double-storey extension (also called a two-storey extension) adds rooms on both the ground and first floor in one build. It typically gives a larger kitchen or living space downstairs and an extra bedroom or bathroom above.
How much does a double-storey extension cost in South Yorkshire?
In South Yorkshire, a double-storey extension typically costs £1,550–£2,300 per m² of floor area (both floors), including VAT at 20% (standard rate). For a typical 36 m² project that is roughly £56,000–£83,000. That range is adjusted for Yorkshire and the Humber, where domestic building work typically costs around 7% below the national average. Design, structural calculations and council fees are extra.
| Size or type | Guide range |
|---|---|
| Smaller project (25 m²) | £39,000–£57,500 |
| Typical project (36 m²) | £56,000–£83,000 |
| Larger project (50 m²) | £77,500–£115,000 |
| Rate per m² | £1,550–£2,300 |
What moves the price most:
- Bathrooms or en-suites on the first floor
- Total floor area across both floors
- Brick matching and external finishes
- Steel beams where walls are opened up
For a figure based on your own measurements, try the guide price tool, then book a free home visit for a fixed quote.
Do you need planning permission for a double-storey extension in South Yorkshire?
The approval route for South Yorkshire is set by planning law in England. In England an extension of more than one storey can only be permitted development at the rear, no more than 3 metres deep and at least 7 metres from the rear boundary, with matching materials and any upper side windows obscure-glazed. Most double-storey extensions therefore go through a householder planning application.
Building regulations approval comes from the council’s building control service or a registered building control approver. The work is inspected at key stages, such as foundations, drainage and insulation, and a completion certificate is issued at the end.
Our first visit includes a check of your planning history, so you know the route before paying for drawings.
What we handle
From survey to sign-off, the job normally involves:
- Foundations, drainage and scaffolding
- Design drawings and planning application
- Brick or block walls, floors and a roof tied into the house
- Opening up at both levels with steel beams
- Building control sign-off
- Windows, doors and staircase alterations
How long does it take?
Build time is typically 14 to 20 weeks on site, after planning and building control approval. Allow time beforehand for drawings and approvals, usually 3 to 4 months.
Building in South Yorkshire
Yorkshire and the Humber has stone and brick terraces as well as inter-war and newer estates, so materials matching is an early design question.
Towns we cover in South Yorkshire include Sheffield, Rotherham, Doncaster, Barnsley, Bentley and Chapeltown.
How it works
- 01
Survey and brief
We visit, discuss your ideas and budget, and survey the property or site at no cost.
- 02
Drawings and written quote
We prepare the design and give you a written, itemised quote with inclusions and exclusions.
- 03
Approvals
Planning or permitted development confirmation, building regulations and any party wall matters.
- 04
Build and handover
Work follows the agreed programme, with inspections along the way and a completion certificate at the end.
Questions about double-storey extensions in South Yorkshire
Is a double-storey extension cheaper per square metre?
Usually yes. You pay for one set of foundations and one roof but get two floors of space, so the cost per square metre is often lower than a single-storey extension.
How long does a double-storey extension take in South Yorkshire?
Typically 14 to 20 weeks on site, after planning and building control approval. Design and approvals beforehand usually take 3 to 4 months.
Does a double-storey extension need planning permission?
Usually. In England a two-storey rear extension can only be permitted development if it is no more than 3 metres deep and at least 7 metres from the rear boundary, and side extensions over one storey always need permission. In practice most are approved through a planning application.
Will the first floor need a new staircase?
Not normally. The new rooms are reached from the existing landing, though a doorway or short corridor may need to be formed.
How much does a double-storey extension cost in South Yorkshire?
In South Yorkshire, a double-storey extension typically costs £1,550–£2,300 per m² of floor area (both floors), including VAT at 20% (standard rate). A typical 36 m² project comes to roughly £56,000–£83,000. Your fixed price depends on the survey and drawings.