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 Bristol?
In Bristol, a double-storey extension typically costs £1,700–£2,550 per m² of floor area (both floors), including VAT at 20% (standard rate). For a typical 36 m² project that is roughly £61,000–£92,000. Prices in the South West sit near the national average for this kind of work, and the range for Bristol reflects that. Design, structural calculations and council fees are extra.
| Size or type | Guide range |
|---|---|
| Smaller project (25 m²) | £42,500–£64,000 |
| Typical project (36 m²) | £61,000–£92,000 |
| Larger project (50 m²) | £85,000–£127,500 |
| Rate per m² | £1,700–£2,550 |
The biggest cost drivers are:
- Steel beams where walls are opened up
- Roof design and how it joins the existing roof
- Bathrooms or en-suites on the first floor
- Brick matching and external finishes
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 Bristol?
Here is how the rules work for a double-storey extension 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
On a typical double-storey extension we handle:
- Windows, doors and staircase alterations
- Opening up at both levels with steel beams
- Structural engineer’s calculations
- Foundations, drainage and scaffolding
- Building control sign-off
- Brick or block walls, floors and a roof tied into the house
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 Bristol
The South West mixes stone and render cottages with post-war and newer estates, and local materials matter more here when matching an extension.
We cover the whole of Bristol.
How it works
- 01
Free visit
We look at the property, talk through what you want and measure up. There is no charge and no obligation.
- 02
Drawings and written quote
We prepare the design and give you a written, itemised quote with inclusions and exclusions.
- 03
Approvals in place
We handle planning, building control and neighbour notices before work starts.
- 04
Construction and completion
We build, put right any snags and hand over the building control certificate.
Questions about double-storey extensions in Bristol
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 Bristol?
In Bristol, a double-storey extension typically costs £1,700–£2,550 per m² of floor area (both floors), including VAT at 20% (standard rate). A typical 36 m² project comes to roughly £61,000–£92,000. Your fixed price depends on the survey and drawings.
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.
Do you build double-storey extensions in Bristol?
Yes. We build double-storey extensions across Bristol, including postcodes BS0, BS1, BS10, BS11 and BS13. Every project starts with a free home visit.