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 Oldham?
In Oldham, a double-storey extension typically costs £1,550–£2,350 per m² of floor area (both floors), including VAT at 20% (standard rate). For a typical 36 m² project that is roughly £56,000–£84,500. The guide for Oldham reflects typical costs in the North West, roughly 6% below the UK-wide figure. Design, structural calculations and council fees are extra.
| Size or type | Guide range |
|---|---|
| Smaller project (25 m²) | £39,000–£59,000 |
| Typical project (36 m²) | £56,000–£84,500 |
| Larger project (50 m²) | £77,500–£117,500 |
| Rate per m² | £1,550–£2,350 |
The main things that change the cost:
- Steel beams where walls are opened up
- Brick matching and external finishes
- Bathrooms or en-suites on the first floor
- Total floor area across both floors
Your exact price depends on the survey and drawings. The guide price tool gives a quick range in the meantime.
Do you need planning permission for a double-storey extension in Oldham?
Approvals for a double-storey extension in Oldham follow the rules for 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.
We check this for your address before design work starts, so there are no surprises later.
What we handle
From survey to sign-off, the job normally involves:
- Foundations, drainage and scaffolding
- Electrics, heating, plumbing and plastering
- Windows, doors and staircase alterations
- Design drawings and planning application
- Opening up at both levels with steel beams
- Brick or block walls, floors and a roof tied into the house
How long does it take?
Expect 14 to 20 weeks on site, after planning and building control approval. Design and approvals come first and typically take 3 to 4 months, depending on the approval route.
Building in Oldham
The North West has many brick terraces and inter-war semis, where kitchen extensions and dormer loft conversions add space without moving.
If your home is in Oldham or close by in Chadderton, Royton and Failsworth, a free home visit is the first step.
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
Construction and completion
We build, put right any snags and hand over the building control certificate.
Questions about double-storey extensions in Oldham
How long does a double-storey extension take in Oldham?
Typically 14 to 20 weeks on site, after planning and building control approval. Design and approvals beforehand usually take 3 to 4 months.
Can I live at home during the work?
Most families stay put. The shell is built first and the house is opened up late in the job, so disruption inside is limited to a few weeks.
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.
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 much does a double-storey extension cost in Oldham?
In Oldham, a double-storey extension typically costs £1,550–£2,350 per m² of floor area (both floors), including VAT at 20% (standard rate). A typical 36 m² project comes to roughly £56,000–£84,500. Your fixed price depends on the survey and drawings.