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 Benfleet?
In South Benfleet, a double-storey extension typically costs £1,750–£2,650 per m² of floor area (both floors), including VAT at 20% (standard rate). For a typical 36 m² project that is roughly £63,000–£95,500. That range is adjusted for the East of England, where domestic building work typically costs around 6% above the national average. Design, structural calculations and council fees are extra.
| Size or type | Guide range |
|---|---|
| Smaller project (25 m²) | £44,000–£66,000 |
| Typical project (36 m²) | £63,000–£95,500 |
| Larger project (50 m²) | £87,500–£132,500 |
| Rate per m² | £1,750–£2,650 |
Your quote will depend mainly on:
- Steel beams where walls are opened up
- Total floor area across both floors
- Roof design and how it joins the existing roof
- Brick matching and external finishes
A guide range is only a starting point: the guide price tool gives an instant figure for your size, and a free survey turns it into a fixed quote.
Do you need planning permission for a double-storey extension in South Benfleet?
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.
Where work involves a shared wall, building on the boundary, or digging foundations within 3 metres of a neighbour’s building and deeper than its foundations (or within 6 metres for deeper work), the Party Wall etc. Act 1996 applies and notices must be served before work starts.
At the survey we check your house’s planning history and any restrictions, and tell you which route applies.
What we handle
From survey to sign-off, the job normally involves:
- Foundations, drainage and scaffolding
- Design drawings and planning application
- Electrics, heating, plumbing and plastering
- Brick or block walls, floors and a roof tied into the house
- Structural engineer’s calculations
- Building control sign-off
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 Benfleet
Across the East of England, 1930s and post-war semis, newer estates and rural cottages all feature, each with different extension and loft options.
We work across South Benfleet and neighbouring areas such as Hadleigh, Pitsea and Canvey Island. Postcodes we cover in South Benfleet include SS7.
How it works
- 01
Visit and measured survey
A free visit to understand the project, check access and take measurements.
- 02
Design and pricing
Design options, then a fixed quote based on the chosen drawings and specification.
- 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 Benfleet
How much does a double-storey extension cost in South Benfleet?
In South Benfleet, a double-storey extension typically costs £1,750–£2,650 per m² of floor area (both floors), including VAT at 20% (standard rate). A typical 36 m² project comes to roughly £63,000–£95,500. Your fixed price depends on the survey and drawings.
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 long does a double-storey extension take in South Benfleet?
Typically 14 to 20 weeks on site, after planning and building control approval. Design and approvals beforehand usually take 3 to 4 months.
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 close can it be to my neighbour?
Councils look at loss of light and outlook for neighbours. Many apply a 45-degree guideline from the nearest neighbouring window. We design to the council’s published guidance to give the application the best chance.