Lowestoft, Suffolk
Semi-detached rear extension in Lowestoft
Single or two-storey extensions for semi-detached houses, with side access and one party wall. If you live in Lowestoft and want to know what a semi-detached rear extension would cost and whether it needs planning, start with the online guide price or a free site visit.
Lowestoft sits in Suffolk, with postcode districts including NR32 and NR33. Where a Lowestoft semi already has a small lean-to at the back, we usually replace it rather than extend it.
Book a free site visit
Tell us about the house and we'll call to arrange a free, no-obligation visit.
How much does a semi-detached rear extension cost in Lowestoft?
For Lowestoft we work from the East of England rate: £2,010–£3,290 per square metre of new floor, including VAT, standard specification. East of England prices run slightly above our West Midlands baseline; clay soils near trees are the main foundation variable.
| Size | Guide price inc VAT |
|---|---|
| 3 m wide × 4 m deep (12 m²) | £24,000–£39,500 |
| 4 m wide × 5 m deep (20 m²) | £40,500–£65,500 |
| 4 m wide × 6 m deep (24 m²) | £48,500–£79,000 |
Ground conditions, glazing, the roof and how far the house is opened up move the final figure within the range.
Do you need planning permission for a semi-detached rear extension in Lowestoft?
The planning route for a semi-detached rear extension in Lowestoft is set by England's householder rules and your council.
English permitted development (Class A) allows a single-storey rear extension of 3 metres on a terraced or semi-detached house and 4 metres on a detached one, measured from the original house, with a maximum height of 4 metres and eaves of no more than 3 metres within 2 metres of a boundary.
A two-storey rear extension can be permitted development in England only if it projects no more than 3 metres, stays at least 7 metres from the rear boundary, matches the existing roof pitch and has obscure-glazed upper side windows. In practice most double-storey rear extensions go through a householder planning application.
England also has the larger home extension route: a single-storey rear extension of up to 6 metres on an attached house or 8 metres on a detached house, after prior approval from the council. The council notifies your neighbours and has 42 days to decide; the fee is £249 (£310 for applications made from 8 December 2026). The route is not available on designated land such as conservation areas.
Conservation areas, National Parks, National Landscapes and the Broads restrict permitted development, and listed buildings always need listed building consent. At the first visit we measure what is there now and tell you which route fits: permitted development, prior approval or a planning application.
What are homes in Lowestoft like to extend?
Lowestoft mixes Victorian terraces with 1930s semis, so both side returns and full-width kitchen extensions suit houses here.
How a semi-detached rear extension in Lowestoft comes together
Look round and measure
A free visit to see the back of the house, measure it, check the drains and boundaries and hear what you need.
Options and costs
We draw layout options and price each one, so the budget shapes the design rather than surprising you later.
Approvals
Permitted development check, prior approval or planning application, then Building Regulations drawings and structural calculations, plus party wall notices where they apply.
Written price, then build
Once the design and approvals are in place, you get a fixed written price and programme, and we build through to sign-off.
Semi-detached rear extensions near Lowestoft
From Lowestoft, the nearest places we also cover are Bradwell (7.1 miles) and Beccles (7.9 miles).
- Semi-detached rear extension in Bradwell
- Semi-detached rear extension in Beccles
- Semi-detached rear extension in Great Yarmouth
- Semi-detached rear extension in Norwich
- Semi-detached rear extension in Bowthorpe
Other work in Lowestoft:
FAQ
Semi-detached rear extension questions in Lowestoft
Do you handle building control in Lowestoft?
Yes. We apply to the council or a registered building control approver and hand over the completion certificate.
Do I need a party wall agreement?
In England, usually yes if the extension is on or near a shared boundary or the foundations are close to a neighbour's building. We serve the notices.
Do I need a party wall agreement?
Usually with the attached neighbour, in England and Wales.
Will I need a structural engineer?
Yes for the beam over the new opening and usually the foundations; we arrange them and their calculations go to building control.
How long does a rear extension take to build in Lowestoft?
Most single-storey rear extensions take 10 to 16 weeks on site and two-storey extensions 16 to 26 weeks, after design and approvals.
How much does a semi-detached rear extension cost in Lowestoft?
As a guide, £2,010–£3,290 per square metre including VAT for a standard specification. For example, 3 m wide × 4 m deep (12 m²): about £24,000–£39,500 at that rate. Your written price follows the survey.