Building regulations for extensions in Harpenden
We prepare building regulations for extensions for homes in Harpenden, as a stand-alone service or as the first stage of a design and build project.
- Guide price in HarpendenFrom £950 inc VAT
- Approval routeFull plans or building notice
- Timescale2–5 weeks for drawings
- Postcode districtsAL5
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.
Applications are decided by the local planning authority (your district, borough or unitary council).
Extensions in and around Harpenden
Site visits are available across Harpenden (AL5). The same team covers St Albans (5 miles), Hemel Hempstead (6 miles), Welwyn Garden City (6 miles), Hatfield (7 miles), all within easy reach.
Across the East of England many houses sit on generous plots, and single-storey and wraparound extensions are a natural fit.
Design and approval fees for Harpenden
Guide fees for Harpenden including VAT, using our East of England factor of ×1.06. Council and building control charges are not included.
| 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.
Try the guide-price tool to see a range for your own size and finish.
What we take care of
- Completion certificate on sign-off
- Structural calculations for beams, lintels and foundations
- Submission to the council or a registered building control approver
- Energy and glazing checks, including whole-house calculations if needed
- Inspection bookings throughout the build
- Building regulations drawings and written specification
Building regulations approval and planning permission are separate. A design can have planning consent and still need changes to meet the regulations, which is why we draw for both together.
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
First, a site visit: we look at the house, garden, access and drains and listen to what you need.
Design and approvals
Once the layout is agreed, we deal with the council: planning permission or written confirmation that none is needed, plus building control.
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.
Common questions in Harpenden
Do you cover all of Harpenden?
Yes. We cover Harpenden and the surrounding parts of Hertfordshire. Site visits are free and there is no obligation.
Can I see a price before committing to anything?
Yes. The guide prices on this page are adjusted for Harpenden, and the guide-price tool gives a range for your own size. After the survey you get a written price before anything is agreed.
Will my neighbours in Harpenden 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.
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.
What are the insulation standards for an extension?
In England, new walls in an extension should achieve a U-value of 0.18 W/m²K, roofs 0.15 and floors 0.18, with windows at 1.4 and rooflights at 2.2. Wales, Scotland and Northern Ireland set their own figures.
Book a free site visit in Harpenden
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.