Building regulations for extensions across Welwyn Garden City
We prepare building regulations for extensions for homes in Welwyn Garden City, as a stand-alone service or as the first stage of a design and build project.
- Guide price in Welwyn Garden CityFrom £950 inc VAT
- Approval routeFull plans or building notice
- Timescale2–5 weeks for drawings
- Postcode districtsAL6, AL7, AL8, AL10
Local to Welwyn Garden City
Postcode districts we cover around Welwyn Garden City include AL6, AL7, AL8, AL10. Neighbouring towns we cover include Hatfield (3 miles), Hertford (6 miles), St Albans (6 miles), Harpenden (6 miles).
Just over the Bedfordshire border, Luton is about 10 miles away. The East of England mixes market-town terraces, inter-war semis and modern estates. Clay soils are common in parts of the region, which can affect foundation design.
Will the council need to approve it?
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.
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.
Building over or within 3 m of a public sewer needs the water company's consent, usually through a build-over agreement, before the foundations go in.
Applications are decided by the local planning authority (your district, borough or unitary council).
What it costs in Welwyn Garden City
These are guide fees for Welwyn Garden City, adjusted for East of England (×1.06) and including VAT. Council application and inspection fees are paid separately.
| Option | What it covers | Guide price |
|---|---|---|
| Essential | Building regulations drawings for a simple single-storey extension | £950 – £1,950 |
| Standard | Drawings plus structural calculations | £1,350 – £2,800 |
| Premium | Complex or two-storey pack with energy calculations | £2,300 – £4,050 |
Our design fee only. Building control charges are set by your council (or, in England and Wales, a registered building control approver) and quoted separately.
For a figure based on your own dimensions, use our guide-price tool.
Included in a typical project
- Structural calculations for beams, lintels and foundations
- Submission to the council or a registered building control approver
- Inspection bookings throughout the build
- Energy and glazing checks, including whole-house calculations if needed
- Completion certificate on sign-off
Our process, step by step
Site visits are free and there is no obligation. Where drawings are needed, the design stage is priced in writing before it starts.
Free site visit
A designer visits, takes measurements and photos, and discusses layouts, budget and timing with you.
Design and approvals
We draw the design, agree it with you and handle planning or permitted development checks and building regulations.
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 answered
Will my neighbours in Welwyn Garden City be involved?
If a planning application or prior approval is needed, the council notifies neighbours. If the work is on or near a shared boundary, party wall notices may also be needed.
Can I see a price before committing to anything?
Yes. The guide prices on this page are adjusted for Welwyn Garden City, and the guide-price tool gives a range for your own size. After the survey you get a written price before anything is agreed.
How long does this take for a Welwyn Garden City home?
2–5 weeks for drawings, depending on the council and the complexity of the project.
Full plans or building notice?
A full plans application gets the drawings checked before work starts, which we usually recommend for extensions. A building notice is quicker to submit but carries more risk if something needs changing on site.
Who are building control?
Either your local council’s building control team or a registered building control approver. Both inspect the work and issue the 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.