Planning permission for extensions across Harpenden
We prepare planning permission 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 £350 inc VAT
- PlanningWe find the right route for you
- Timescale8–13 weeks typical decision period
- Postcode districtsAL5
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 | Permitted development confirmed in writing (certificate or notification) | £350 – £700 |
| Standard | Householder planning application handled | £600 – £1,200 |
| Premium | Application with heritage or design statements, and responses to the council | £950 – £1,700 |
Our handling fee only. Council fees are extra: in England from 1 April 2026 a householder application is £548, a lawful development certificate for a proposed extension £274 and a larger home extension prior approval £249. Drawings are priced separately.
Want a range for your exact size? The guide-price tool takes about a minute.
Working in Harpenden
Our survey diary covers Harpenden, including 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.
Who this service is for
- Projects in conservation areas or with previous refusals
- Homeowners who would rather not deal with the council themselves
- Anyone unsure whether their extension needs permission
A lawful development certificate is not compulsory for permitted development, but it is the cleanest proof that the extension was lawful when you come to sell. We usually recommend one.
Planning and approvals in Harpenden
In England the main routes are permitted development (ideally confirmed with a lawful development certificate, £274), larger home extension prior approval (£249, 42 days) and a householder planning application (£548, normally 8 weeks), with council fees as set from 1 April 2026.
The planning position for a specific Harpenden address depends on its history and any designations, which is why we check it at the first visit.
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.
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.
Applications are decided by the local planning authority (your district, borough or unitary council).
From first visit to completion
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 Harpenden 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.
Questions answered
Who do I contract with in Harpenden?
Your contract is with S&K Property Investments and Improvement Ltd, which designs and manages the project and the build teams who carry it out.
How long does this take for a Harpenden home?
8–13 weeks typical decision period, depending on the council and the complexity of the project.
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.
What happens if planning is refused?
You can revise the design and reapply, or appeal. We read the officer’s report and tell you honestly which option has a better chance.
How much does planning permission cost?
In England, from 1 April 2026 the council fee is £548 for a householder application, £274 for a lawful development certificate for a proposed extension and £249 for larger home extension prior approval. Our handling fee is separate.
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.