Home extensions in Welwyn Garden City
From a small utility to a two-storey addition, we take on house extensions throughout Welwyn Garden City, starting with a free visit and a planning check.
- Postcode districtsAL6, AL7, AL8, AL10
- Price regionEast of England (×1.06)
- Planning rulesEngland
- Site visitFree, no obligation
Popular extension prices in Welwyn Garden City
We publish guide prices so you can budget before anyone visits. For Welwyn Garden City they are adjusted by ×1.06, the factor we use across East of England.
| Extension type | Example size | Standard spec (inc VAT) |
|---|---|---|
| Orangery extensions | 16 m² | £47,000 – £59,500 |
| Kitchen extensions | 20 m² | £44,500 – £56,500 |
| Single-storey rear extensions | 20 m² | £43,000 – £55,500 |
| Conservatory replacement extensions | 14 m² | £31,500 – £41,000 |
| Double-storey extensions | 32 m² | £61,000 – £80,000 |
Which extension suits a Welwyn Garden City home?
Across the East of England many houses sit on generous plots, and single-storey and wraparound extensions are a natural fit.
For many houses here, bungalow extensions, wraparound extensions or single-storey rear extensions gives the most useful space for the budget.
Planning and building control in Welwyn Garden City
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 single-storey side extension can be permitted development if it is no more than 4 m high and no wider than half the width of the original house. Two-storey side extensions, and any side extension on designated land such as a conservation area, need a householder planning application.
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.
If the work involves a shared wall, building on the boundary, or digging foundations within 3 m (sometimes 6 m) of a neighbour's building, the Party Wall etc. Act 1996 applies and notice must be served before work starts: two months for work to a party wall, one month for new walls on the boundary and for excavations.
Applications are decided by the local planning authority (your district, borough or unitary council).
Where we work near Welwyn Garden City
Postcode districts we cover around Welwyn Garden City include AL6, AL7, AL8, AL10. Nearby, we also take on projects in Hatfield (3 miles), Hertford (6 miles), St Albans (6 miles), Harpenden (6 miles), Stevenage (7 miles). For homes towards Bedfordshire, Luton is around 10 miles away.
All extension types we build in Welwyn Garden City
- Pitched roof extensions · from £23,500
- Single-storey rear extensions · from £22,000
- Timber frame extensions · from £22,000
- Building regulations for extensions · from £950
- Side extensions · from £23,000
- Bedroom extensions · from £27,500
- Porch extensions · from £4,200
- Kitchen extensions · from £28,500
- Bungalow extensions · from £27,500
- Home office extensions · from £16,500
- Extension plans and drawings · from £1,250
- Wraparound extensions · from £38,000
- Orangery extensions · from £31,500
- Glass box extensions · from £31,500
- Double-storey extensions · from £40,000
- Side return extensions · from £19,000
- Extensions over a garage · from £25,000
- Utility and boot room extensions · from £14,500
- Planning permission for extensions · from £350
- Flat roof extensions · from £22,000
- Annexe extensions · from £58,000
- Conservatory replacement extensions · from £21,000
Free site visit
A designer visits, takes measurements and photos, and discusses layouts, budget and timing with you.
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
We confirm the build price in writing, based on the approved drawings and the finishes you have chosen.
Build and sign-off
Our team builds the extension, keeps you updated weekly and finishes with building control sign-off.
Questions about extensions in Welwyn Garden City
How much does an extension cost in Welwyn Garden City?
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.
Do you cover all of Welwyn Garden City?
Yes, including the surrounding parts of Hertfordshire. Site visits are free and there is no obligation.
How long does an extension take in Welwyn Garden City?
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.
Do I need planning permission for an extension in Welwyn Garden City?
Not always. It depends on the size, position and your property's history. Many single-storey rear extensions in England are permitted development or can use prior approval.
Do you handle building regulations?
Yes. We prepare the drawings and calculations, submit them and book inspections, ending with a completion certificate.
Book a free site visit in Welwyn Garden City
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.