Flat roof extensions in Rickmansworth: design, approvals and build
We design and build flat roof extensions for houses in Rickmansworth, with a written price once the survey and design are done and one point of contact throughout.
- Guide price in RickmansworthFrom £22,000 inc VAT
- PlanningOften permitted development (3–4 m), or prior approval up to 6–8 m
- Build time10–16 weeks on site
- Postcode districtsWD3
Flat roof extension prices in Rickmansworth
For Rickmansworth we adjust our national guide rates by ×1.06, the factor we use for East of England. Figures include VAT; your written quote after the survey replaces them.
Typical rates in Rickmansworth: £1,860 to £3,550 per m² including VAT, depending on specification.
| Size | Essential | Standard | Premium |
|---|---|---|---|
| 3 m × 4 m 12 m² | £22,000 – £26,500 | £26,000 – £33,500 | £33,000 – £43,000 |
| 4 m × 5 m 20 m² | £37,000 – £43,500 | £43,000 – £55,500 | £55,000 – £71,500 |
| 5 m × 6 m 30 m² | £55,500 – £65,500 | £65,000 – £83,000 | £82,500 – £107,000 |
For a figure based on your own dimensions, use our guide-price tool.
Planning rules that apply in Rickmansworth
In England a single-storey rear extension can usually go up to 3 m beyond the original rear wall of a semi-detached or terraced house, or 4 m on a detached house, without a planning application, provided it is no more than 4 m high, keeps eaves to 3 m within 2 m of a boundary and, with other buildings, covers no more than half the land around the original house. The larger home extension prior approval scheme raises those depths to 6 m and 8 m, with neighbours notified and a 42-day decision.
Before any drawing is finalised we check whether the house is listed, in a conservation area or subject to an Article 4 direction.
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).
What we take care of
- Warm-roof design with insulation above the deck
- Parapets or edge trims and flashings to the house
- Falls and outlets designed to drain properly
- Membrane choice: single-ply, EPDM or GRP
Working in Rickmansworth
Site visits are available across Rickmansworth (WD3). We also work in nearby Watford (4 miles), Bushey (5 miles), Hemel Hempstead (8 miles), Borehamwood (9 miles).
Just over the Buckinghamshire border, Chalfont St Peter is about 4 miles away. 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
A designer visits, takes measurements and photos, and discusses layouts, budget and timing with you.
Design and approvals
Drawings are prepared and agreed with you, then submitted for the right planning route and building regulations approval.
Fixed written price
With the design and specification agreed, you get a fixed written price and a start date.
Build and sign-off
We build it with one project manager, book the building control inspections and hand over the completion certificate.
Flat roof extension questions answered
How long does a flat roof extension take to build in Rickmansworth?
On site, typically 10 to 16 weeks once approvals are in place. Before that, allow 4–12 weeks design and approvals.
Do I need building regulations approval in Rickmansworth?
Yes. Almost every extension needs it, whatever the planning route. We prepare the drawings and book the inspections.
Will my neighbours in Rickmansworth 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.
Are flat roof extensions cheaper?
Usually slightly, because there is less roof structure and no tiles. Our guide range is about £1,860 to £3,550 per m² including VAT.
Can I walk on a flat roof extension?
Only for maintenance unless it is designed as a terrace. A roof terrace or balcony needs planning permission and a different structure.
Book a free site visit in Rickmansworth
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.