St Albans, Hertfordshire
Kitchen-diner rear extension in St Albans
An open-plan kitchen, dining and family room that opens straight onto the garden. If you live in St Albans and want to know what a kitchen-diner rear extension would cost and whether it needs planning, start with the online guide price or a free site visit.
St Albans is covered from our Hertfordshire round, including AL1 and AL2. A kitchen-diner is often the reason people in St Albans extend: the back kitchen in post-war semis and newer estates is rarely big enough for a table.
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 kitchen-diner rear extension cost in St Albans?
For St Albans 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 |
These are guide ranges; the written quote after the survey is the figure that counts.
Do you need planning permission for a kitchen-diner rear extension in St Albans?
Here is how the rules in England apply to a kitchen-diner rear extension in St Albans.
Under England's householder permitted development rules you can usually add 3 metres at the back of an attached house, or 4 metres on a detached house, without a planning application, as long as the extension stays under 4 metres high and its eaves stay under 3 metres where it is within 2 metres of a boundary.
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 St Albans like to extend?
Post-war semis and newer estates are typical of St Albans, and many have room for a full-width extension. Shrinkable clay is common in the East of England, so foundations near trees and hedges are designed to NHBC-style depth guidance.
How a kitchen-diner rear extension in St Albans comes together
Free site visit
We measure the house and garden, look at the back wall, drainage and boundaries, and talk through what you want from the space.
Design and guide price
Two or three layout options with a guide price for each, so you choose the design knowing what it costs.
Approvals
Permitted development check, prior approval or planning application, then Building Regulations drawings and structural calculations, plus party wall notices where they apply.
Fixed price and build
A written price for the agreed design, a start date and a named contact through the build, ending with the building control completion certificate.
Kitchen-diner rear extensions near St Albans
From St Albans, the nearest places we also cover are Abbots Langley (4.7 miles) and Harpenden (4.7 miles).
- Kitchen-diner rear extension in Abbots Langley
- Kitchen-diner rear extension in Harpenden
- Kitchen-diner rear extension in Hatfield
- Kitchen-diner rear extension in Hemel Hempstead
- Kitchen-diner rear extension in North Watford
Other work in St Albans:
FAQ
Kitchen-diner rear extension questions in St Albans
Can I live at home while the extension is built?
Usually yes. Most of the work is outside until the back wall is opened near the end, and that stage is screened off.
Can I get a price without a visit?
Our online guide-price tool gives a range in a couple of minutes. A written price needs a survey.
Should the sink face the garden?
If the plan allows, an island sink or hob facing the glass is a common choice. It needs a floor-level drain run, which is easy to lay in a new slab.
Do I need planning permission for a rear extension in St Albans?
Often not for a single-storey rear extension of up to 3 metres (4 metres on a detached house) under permitted development, or up to 6 or 8 metres with prior approval, unless the house is in a conservation area or its rights have been removed.
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.
Can you match the brick or stone on my St Albans house?
We source the closest match and show you samples before ordering; reclaimed materials are often the best match on older houses.