Extending your home in Harwich
We design and build house extensions for homes in Harwich and the surrounding Essex area, with guide prices adjusted for the region.
- Postcode districtsCO12
- Price regionEast of England (×1.06)
- Planning rulesEngland
- Site visitFree, no obligation
Planning rules in Harwich
In England a single-storey rear extension can usually go up to 3 m beyond the original rear wall of a semi-detached or terraced house, or 4 m on a detached house, without a planning application, provided it is no more than 4 m high, keeps eaves to 3 m within 2 m of a boundary and, with other buildings, covers no more than half the land around the original house. The larger home extension prior approval scheme raises those depths to 6 m and 8 m, with neighbours notified and a 42-day decision.
In England a two-storey rear extension is permitted development only if it projects no more than 3 m from the original rear wall, sits at least 7 m from the rear boundary, matches the roof pitch and uses obscure, non-opening side windows upstairs. Most two-storey extensions therefore go through a householder planning application, which costs £548 from 1 April 2026 and normally takes about 8 weeks.
In a conservation area, national park, National Landscape, the Broads or a World Heritage Site the permitted development limits are tighter (no side or two-storey extensions without an application). Listed homes need listed building consent, and if permitted development rights have been removed, any extension needs an application.
Building regulations approval is separate from planning. In England you can use the council's building control team or a registered building control approver; a full plans application gets the drawings checked before work starts, and the inspector signs the work off with a completion certificate.
Applications are decided by the local planning authority (your district, borough or unitary council).
Covering Harwich and nearby
Site visits are available across Harwich (CO12). The same team covers Clacton-on-Sea (12 miles), Colchester (17 miles), Witham (29 miles), Maldon (30 miles), Braintree (31 miles), all within easy reach. Felixstowe, in Suffolk, is roughly 3 miles from Harwich and also on our list.
What works best for Harwich houses?
Across the East of England many houses sit on generous plots, and single-storey and wraparound extensions are a natural fit.
The types we would usually look at first for a home in Harwich are double-storey extensions, single-storey rear extensions and wraparound extensions, depending on the garden and how the house is laid out.
Guide prices for Harwich
We publish guide prices so you can budget before anyone visits. For Harwich they are adjusted by ×1.06, the factor we use across East of England.
| Extension type | Example size | Standard spec (inc VAT) |
|---|---|---|
| Wraparound extensions | 25 m² | £60,500 – £77,000 |
| Kitchen extensions | 20 m² | £44,500 – £56,500 |
| Orangery extensions | 16 m² | £47,000 – £59,500 |
| Side return extensions | 11 m² | £27,500 – £35,000 |
| Double-storey extensions | 32 m² | £61,000 – £80,000 |
Extension types and starting prices
- Building regulations for extensions · from £950
- Double-storey extensions · from £40,000
- Single-storey rear extensions · from £22,000
- Orangery extensions · from £31,500
- Timber frame extensions · from £22,000
- Side extensions · from £23,000
- Flat roof extensions · from £22,000
- Porch extensions · from £4,200
- Extensions over a garage · from £25,000
- Kitchen extensions · from £28,500
- Bungalow extensions · from £27,500
- Wraparound extensions · from £38,000
- Utility and boot room extensions · from £14,500
- Home office extensions · from £16,500
- Side return extensions · from £19,000
- Conservatory replacement extensions · from £21,000
- Annexe extensions · from £58,000
- Glass box extensions · from £31,500
- Extension plans and drawings · from £1,250
- Pitched roof extensions · from £23,500
- Bedroom extensions · from £27,500
- Planning permission for extensions · from £350
Free site visit
First, a site visit: we look at the house, garden, access and drains and listen to what you need.
Design and approvals
We produce the drawings and structural design, and manage the approvals so they are in place before work starts.
Fixed written price
With the design and specification agreed, you get a fixed written price and a start date.
Build and sign-off
Work is carried out to the agreed programme, inspected by building control and signed off at the end.
Questions about extensions in Harwich
How much does an extension cost in Harwich?
Using our East of England factor (×1.06), a standard-spec single-storey extension of 20 m² is a guide £43,000 to £55,500 including VAT, and a 32 m² two-storey extension £61,000 to £80,000. Your written price follows the survey.
How long does an extension take in Harwich?
Usually 2 to 4 months of design and approvals, then 10 to 16 weeks on site for a single-storey extension or 16 to 24 weeks for two storeys.
Can I get a price before anyone visits?
Yes. This page shows guide prices adjusted for Harwich, and the guide-price tool gives a range for your own size and finish in about a minute.
Do you handle building regulations?
Yes. We prepare the drawings and calculations, submit them and book inspections, ending with a completion certificate.
Will my neighbours need to be told?
If you apply for planning or prior approval the council notifies them, and in England party wall notices may be needed for work near a shared boundary.
Book a free site visit in Harwich
We will measure up, check the planning position and give you honest guide figures.
- Free, no-obligation site visit
- Planning route checked before you spend on drawings
- Written price once the design is agreed
- Building control sign-off at the end
Prefer to talk? Call 0800 088 6341 or .
Book a free site visit
Tell us a little about the project and we will arrange a time.