A double-storey extension adds two floors of new space to your house in one build, typically a larger kitchen or living room downstairs with an extra bedroom, bathroom or en-suite above, sharing one set of foundations and one roof.
Looking for a double-storey extension in Essex? We organise the whole job, bringing in the trades it needs under one agreement, and you have a single contact. We cover Southend-on-Sea, Basildon, Colchester and Chelmsford, along with villages and suburbs nearby. The rules in England decide what consents are needed, and our guide range of £63,000–£126,000 including VAT gives you a realistic starting point for a budget.
- Guide price
- £63,000–£126,000 inc VAT
- Time on site
- 14–22 weeks on site
- Planning rules
- England
- Price level
- About 5% above the national guide
- Towns listed
- 23
- Survey
- Free, with a written quote
How much does a double-storey extension cost in Essex?
What should you budget for a double-storey extension in Essex? Use the figures below as a starting point. Prices in the East of England sit about 5% above the national guide, so the range here is £63,000–£126,000 including VAT. Your fixed price comes in writing once we've surveyed the property, at no charge.
| Type of job | What it usually involves | Guide in Essex |
|---|---|---|
| Small (15–20m² total) | A compact rear or side extension adding a small room on each floor. | £42,000–£68,000 |
| Typical (30–40m² total) | A larger kitchen or living room below with a double bedroom or en-suite above. | £63,000–£126,000 |
| Large (50m² plus total) | Wide or deep extensions, often with a new bathroom, steelwork and high-spec glazing. | £105,000–£189,000 |
The main things that change the figure:
- How the new roof joins the existing roof
- Bathrooms, en-suites and plumbing on the upper floor
- Foundation depth, ground conditions and drains to divert
- Scaffolding duration, access and the level of finishes
What’s included?
- Insulated cavity walls with brick or render to match the house
- First-floor joists, stud walls and new openings upstairs
- Roof structure tied into the existing roof, tiled to match
- Scaffolding for the full build, erected and inspected
- Electrics, plumbing and heating by qualified trades, with certificates
- Windows, external doors, plastering and internal doors
Homes in Essex
Essex ranges from timber-framed and weatherboarded cottages in the north, some with decorative pargeting, to Victorian terraces in Colchester, Chelmsford and Southend. Basildon and Harlow were built as post-war new towns, much of the south-east has interwar suburbs and bungalows, and large new estates continue to appear around Chelmsford and Braintree.
Terraces and semis commonly suit loft conversions and rear extensions, and many bungalows can take a loft room. New-town homes often need cladding, window and roofline renewal, while timber-framed cottages call for lime plaster and repairs that respect the original frame.
Essex is one of the driest counties in England, and London Clay in the south shrinks in dry spells, so trees and foundation depth matter.
Planning and building rules in Essex
Homes in Essex come under the regulations for England, summarised below. We don't rely on general rules alone: we confirm the position for your address with the council before a quote goes out.
In England, a two-storey rear extension can only be permitted development if it is no more than 3 m deep, at least 7 m from the rear boundary and finished to match the house. Most double-storey and all two-storey side extensions need full planning permission.
Building Regulations approval is needed, with structural calculations for beams, foundations and the roof. The Party Wall etc. Act 1996 often applies on semi-detached and terraced houses.
Rules change and every property is different, so we check the planning history and constraints for your address before we quote.
How does the job run?
A visit to your home
It starts with a survey at the property, free of charge. We check condition, access and services, ask how you want the finished result to look, and answer any questions you have about a double-storey extension.
Written quote
Next you receive a written quote with a fixed price for the agreed specification. It lists what is included, what is not, and how payments are staged, so you can compare it properly.
Booking the work
Next comes planning the work itself. We set a start date that suits you, line up the right trades, and make sure any approvals for a double-storey extension are in place before the first day on site.
On site to finish
The work is carried out to the agreed specification, with floors and furniture protected and the site kept tidy. At the end we clean up, walk through the finished job with you and hand over any certificates.
What you can expect from us
Questions about a double-storey extension in Essex
Do you cover Southend-on-Sea, Basildon and Colchester?
Yes. As well as Essex, we cover Southend-on-Sea, Basildon and Colchester and the rest of Essex. Our coverage is UK-wide, so the process is the same wherever you are: a free site survey, a quote in writing that fixes the price for the agreed scope, and one point of contact while the work is planned and carried out.
Will the extension affect my neighbours?
A double-storey extension can affect neighbours' light, outlook and privacy, which is why planning departments look closely at height, depth and window positions. Side windows facing neighbours often need obscure glass. Work near a shared wall may also need party wall notices; the Party Wall etc. Act 1996 applies in England and Wales only. We talk through these points early so the design is realistic.
How is the new roof joined to the existing house?
The new roof is usually tied into the existing roof so the two read as one. On a rear extension this often means a lower ridge or a hipped end, with valleys where the slopes meet. We strip back some existing tiles, fix new rafters and battens, and lay matching tiles or slates. Lead or proprietary flashings seal the junctions so water runs off properly.
Who do I deal with during the job?
One point of contact manages your project from survey to handover. They schedule the trades working under our contract, keep you updated on progress, and are the person to call with any question. You don't need to coordinate builders, electricians or decorators separately, because that is part of what we do.
Can the new upstairs room have its own bathroom?
A new upstairs room can usually have an en-suite, provided waste pipes can reach the soil stack or a new one can be installed. Running the waste pipe to the right falls is the main design question, and a pumped system is an option where gravity will not work. We plan bathroom positions at the design stage so pipes, ventilation and insulation are built in rather than added later.
Towns in Essex
These are the towns in Essex where you can book a free survey for a double-storey extension. Each has its own page with guide prices and coverage details.