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Flat roof extensions for homes in Risca

Thinking about a flat roof extension for your Risca home? Start with a free site visit: we measure up, check what the council will allow and give you honest guide figures on the day.

  • Guide price in RiscaFrom £19,500 inc VAT
  • PlanningWelsh permitted development rules (rear up to 4 m)
  • Build time10–16 weeks on site
  • Postcode districtsNP11
Flat roof of an extension with a membrane finish, a roof lantern and flat rooflights

Will the council need to approve it?

In Wales a single-storey rear extension can usually project up to 4 m beyond the rear wall without a planning application, if it is no more than 4 m high, keeps eaves to 3 m and overall height to 4 m within 2 m of a boundary, and covers no more than half the land around the original house. Wales has no larger home extension prior approval scheme.

Homes in conservation areas, national parks, National Landscapes (AONBs) 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 before the foundations go in.

Building regulations approval is separate from planning. Wales has its own building regulations and approved documents; the council or a registered building control approver checks the plans, inspects the work and issues a completion certificate.

Applications are decided by the local planning authority (your county or county borough council, or the national park authority).

Guide prices for Risca

Labour and material costs vary across the UK, so for Risca we use our Wales factor (×0.93). The ranges include VAT and exclude design, structural and council fees.

Typical rates in Risca: £1,630 to £3,120 per m² including VAT, depending on specification.

SizeEssentialStandardPremium
3 m × 4 m
12 m²
£19,500 – £23,000£22,500 – £29,500£29,000 – £37,500
4 m × 5 m
20 m²
£32,500 – £38,500£38,000 – £48,500£48,000 – £62,500
5 m × 6 m
30 m²
£48,500 – £57,500£57,000 – £73,000£72,500 – £93,500

Want a range for your exact size? The guide-price tool takes about a minute.

Extensions in and around Risca

Postcode districts we cover around Risca include NP11. The same team covers Caerphilly (6 miles), Blackwood (6 miles), Gelligaer (8 miles), Pontypridd (10 miles), all within easy reach.

Just over the Gwent border, Newport, Gwent is about 5 miles away. In Wales, terraced houses with rear offshoots are common in the towns, while detached houses and bungalows dominate in rural areas.

Is a flat roof extension right for your house?

  • Modern and 1930s onwards houses
  • Homeowners who want maximum light from above
  • Extensions under first-floor windows where a pitch will not fit

Height is often what decides a flat roof. Under first-floor windows, a pitched roof may not fit at all; a flat roof keeps the extension low while still giving a good ceiling height inside.

How the project works

Site visits are free and there is no obligation. Where drawings are needed, the design stage is priced in writing before it starts.

  1. Free site visit

    It starts with a visit to your house to measure, check access and talk through ideas and budget.

  2. Design and approvals

    Drawings are prepared and agreed with you, then submitted for the right planning route and building regulations approval.

  3. Fixed written price

    The price is fixed in writing once the design is settled, with a clear programme and payment stages.

  4. Build and sign-off

    The build is managed from start to finish, inspected at each stage and signed off on completion.

Questions people ask about flat roof extensions

Can I see a price before committing to anything?

Yes. The guide prices on this page are adjusted for Risca, and the guide-price tool gives a range for your own size. After the survey you get a written price before anything is agreed.

Who do I contract with for a flat roof extension in Risca?

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.

Do I need building regulations approval in Risca?

Yes. Almost every extension needs it, whatever the planning route. We prepare the drawings and book the inspections.

Are flat roof extensions cheaper?

Usually slightly, because there is less roof structure and no tiles. Our guide range is about £1,630 to £3,120 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 Risca

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

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