Annexe extensions in Hitchin: design, approvals and build
From the first sketch to final sign-off, we plan and build annexe extensions in Hitchin and the surrounding Hertfordshire area.
- Guide price in HitchinFrom £58,000 inc VAT
- PlanningUsually a householder application
- Build time16–24 weeks on site
- Postcode districtsSG4, SG5
When an annexe extension makes sense
- Relatives who need support close by
- Multi-generational families
- Homes with a large side or rear garden
Do I need planning permission in Hitchin?
In England an annexe that stays part of the household and connects to the house is assessed as an extension, but its size usually takes it beyond permitted development, so a householder application describing the ancillary use is the normal route.
Homes in conservation areas, national parks, National Landscapes (formerly AONBs), the Broads and World Heritage Sites have tighter rules, so we always check the property's status and planning history before design starts.
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 should I budget for an annexe extension in Hitchin?
Labour and material costs vary across the UK, so for Hitchin we use our East of England factor (×1.06). The ranges include VAT and exclude design, structural and council fees.
Typical rates in Hitchin: £2,120 to £4,030 per m² including VAT, depending on specification.
| Size | Essential | Standard | Premium |
|---|---|---|---|
| Studio annexe 25 m² | £58,000 – £73,000 | £63,500 – £79,500 | £79,500 – £101,000 |
| One-bedroom annexe 35 m² | £74,000 – £93,000 | £89,000 – £111,500 | £111,000 – £141,000 |
| Larger annexe 45 m² | £95,000 – £119,500 | £114,000 – £143,500 | £143,000 – £181,500 |
Want a range for your exact size? The guide-price tool takes about a minute.
Local to Hitchin
Postcode districts we cover around Hitchin include SG4, SG5. The same team covers Letchworth Garden City (3 miles), Stevenage (5 miles), Harpenden (10 miles), Welwyn Garden City (11 miles), all within easy reach.
Luton, in Bedfordshire, is roughly 7 miles from Hitchin and also on our list. Across the East of England many houses sit on generous plots, and single-storey and wraparound extensions are a natural fit.
What happens next
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
We visit your Hitchin home, measure up, talk through what you want and check the planning position.
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
The build is managed from start to finish, inspected at each stage and signed off on completion.
Annexe extension questions answered
How long does an annexe extension take to build in Hitchin?
On site, typically 16 to 24 weeks once approvals are in place. Before that, allow 10–16 weeks design and approvals.
Do you cover all of Hitchin?
Yes. We cover Hitchin and the surrounding parts of Hertfordshire. Site visits are free and there is no obligation.
Will my neighbours in Hitchin 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.
How much does an annexe extension cost?
Our guide range is about £2,120 to £4,030 per m² including VAT. A one-bedroom annexe of about 35 m² is typically £89,000 to £111,500 at standard spec in Hitchin.
Will an annexe affect council tax?
It can. Some annexes are assessed separately for council tax, with discounts or exemptions in some cases when occupied by a relative. Check with the Valuation Office Agency (England and Wales), your local assessor (Scotland) or Land & Property Services (Northern Ireland).
Book a free site visit in Hitchin
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.