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.
We arrange a double-storey extension for homeowners in Chichester and the wider West Sussex. The job is planned, priced and managed by us and carried out by tradespeople engaged under our contract, so there is one agreement and one contact. On a typical home the work takes 14–22 weeks on site, and guide pricing in the South East is £67,000–£134,000, VAT included.
- Guide price
- £67,000–£134,000 inc VAT
- Time on site
- 14–22 weeks on site
- Postcodes
- PO19
- Planning rules
- England
- Local area
- West Sussex
- Survey
- Free, with a written quote
What should you budget for a double-storey extension in Chichester?
Use the table to gauge the cost of a double-storey extension in Chichester before we visit. Figures include VAT and are scaled for the South East, coming out about 12% above the national guide, which gives £67,000–£134,000 overall. After a free survey, you receive a fixed written price.
| Type of job | What it usually involves | Guide in Chichester |
|---|---|---|
| Small (15–20m² total) | A compact rear or side extension adding a small room on each floor. | £45,000–£73,000 |
| Typical (30–40m² total) | A larger kitchen or living room below with a double bedroom or en-suite above. | £67,000–£134,000 |
| Large (50m² plus total) | Wide or deep extensions, often with a new bathroom, steelwork and high-spec glazing. | £112,000–£202,000 |
What moves the price up or down:
- Combined floor area across both storeys
- How the new roof joins the existing roof
- Bathrooms, en-suites and plumbing on the upper floor
- Scaffolding duration, access and the level of finishes
Scope of the work
- 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
What are homes like around Chichester?
Chichester has Georgian brick streets, Downland villages use flint and brick, and Horsham stone slabs cover some older roofs. Worthing and Bognor Regis have interwar and post-war bungalows and semis, Crawley was planned as a post-war new town, and Wealden villages to the north feature tile-hanging and timber framing.
Coastal towns face salt-laden south-westerly winds, while Wealden clay inland can shrink and swell with the seasons.
So when we survey a Chichester property for a double-storey extension, the first step is working out how it was built and what has been changed since.
Permissions for a double-storey extension in Chichester
Homes in Chichester 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?
Free site survey
Book a visit and we'll come to you. The survey covers measurements, the state of what's there now and any obvious constraints, so the price that follows is based on your actual home, not an average.
Quote in writing
You get the price in writing, itemised so you can see where the money goes. As long as the specification stays the same, that is the price you pay for a double-storey extension.
Booking the work
Once you accept, we agree start dates, order materials and deal with any planning, building control or neighbour notices the job needs. You'll know who is coming and when before work begins.
Finish and handover
During the work we protect the areas around it and tidy up at the end of each day. Once complete, we check the finish, remove our materials and hand over paperwork such as building control sign-off where it applies.
How we work
Double-storey extensions in Chichester: questions
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.
Can I stay at home during the work?
In most cases, yes. Most people can live at home throughout, and we plan the work to keep disruption down by protecting floors, agreeing working hours and keeping access routes clear. Bigger jobs affecting kitchens, bathrooms or heating may mean a short spell with reduced facilities, and we talk this through with you at the survey.
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.
Can you combine a double-storey extension with other work?
Yes. Because we manage several trades under one contract, we can plan a double-storey extension alongside other work on your Chichester home, such as new windows with rendering, or a kitchen refit with an extension. Combining jobs can reduce repeat set-up such as scaffolding, skips and access, and every element is listed and priced in the same written quote.
Nearby towns
If your address falls within PO19, we cover it. The same goes for neighbouring Bognor Regis, Emsworth and Havant, which we include alongside Chichester when arranging surveys and quotes.