Harpenden porch extensions, designed and built
Harpenden homeowners can use us for the whole porch extension project: survey, design, planning or permitted development checks, building regulations and the build itself.
- Guide price in HarpendenFrom £4,200 inc VAT
- PlanningUsually permitted development under 3 m²
- Build time2–4 weeks on site
- Postcode districtsAL5
What should I budget for a porch extension in Harpenden?
Prices below are for Harpenden, using the East of England factor of ×1.06. They are guide ranges including VAT for the build only, not a quote.
| Option | What it covers | Guide price |
|---|---|---|
| Essential | Small brick or glazed porch, up to 3 m² | £4,200 – £6,900 |
| Standard | Brick porch with tiled roof and composite door | £6,350 – £10,100 |
| Premium | Larger porch with WC or oak frame and premium glazing | £9,500 – £15,900 |
Want a range for your exact size? The guide-price tool takes about a minute.
Planning rules that apply in Harpenden
In England a porch is usually permitted development if its ground floor area is no more than 3 m² measured externally, no part is over 3 m high, and no part is within 2 m of a boundary next to a road.
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).
Included in a typical project
- Tiled, slate or flat roof
- Planning check against the porch limits
- Brick, render or oak frame walls
- Front door, glazing and electrics
Local to Harpenden
We cover Harpenden and the postcode districts AL5. We also work in nearby St Albans (5 miles), Hemel Hempstead (6 miles), Welwyn Garden City (6 miles), Hatfield (7 miles).
Just over the Bedfordshire border, Luton is about 5 miles away. Across the East of England many houses sit on generous plots, and single-storey and wraparound extensions are a natural fit.
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
It starts with a visit to your house to measure, check access and talk through ideas and budget.
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.
Common questions in Harpenden
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.
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.
Do I need planning permission for a porch?
In England a porch is usually permitted development if its ground floor area is no more than 3 m² (measured externally), no part is higher than 3 m, and no part is within 2 m of a boundary next to a highway. Other nations have similar but separate rules.
How much does a porch cost?
Our guide range is about £4,200 to £15,900 including VAT, depending on size, materials and whether it includes a WC.
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.