A single-storey extension is a new ground-floor room built onto your house, usually at the rear or side, with its own foundations, walls and roof, creating a bigger kitchen, living space or bedroom without moving home.
Anyone planning a single-storey extension in Caerphilly wants three things: a clear price, a realistic timetable and a tidy job. We publish a guide of £32,000–£69,000 including VAT for Wales up front, explain that work normally takes 10–16 weeks on site, and confirm both in writing after a free survey of your property.
- Guide price
- £32,000–£69,000 inc VAT
- Time on site
- 10–16 weeks on site
- Postcodes
- CF83
- Planning rules
- Wales
- Local area
- Mid Glamorgan
- Survey
- Free, with a written quote
What should you budget for a single-storey extension in Caerphilly?
In Caerphilly, guide figures for a single-storey extension sit at £32,000–£69,000, VAT included. We set them using rates for Wales, currently about 8% below the national guide. The table shows what pushes a project towards either end of the range; your own price is set after a free survey.
| Type of job | What it usually involves | Guide in Caerphilly |
|---|---|---|
| Small extension (8–12m²) | A modest rear or side extension, such as a utility room or a slightly larger kitchen. | £20,000–£37,000 |
| Typical rear extension (15–25m²) | A kitchen-diner or family room with bifold doors and a rooflight or lantern. | £32,000–£69,000 |
| Large or wrap-around (30m² plus) | A wrap-around or wide rear extension, often with structural steelwork into the house. | £64,000–£120,000 |
Expect these to shape the final quote:
- Roof type, rooflights, lanterns and the amount of glazing
- Ground conditions, foundation depth and drains to divert
- Steelwork needed to open into the existing house
- Finishes, kitchen, flooring and heating specification
What do you get?
- Groundworks, foundations and below-ground drainage
- Cavity walls built and insulated to building regulations
- Flat or pitched roof, with rooflights or a lantern if specified
- Steel beams to open into the existing house
- Electrics and plumbing by qualified trades, with certificates
- Plastering, screed floor and internal doors
Local housing and a single-storey extension
The Rhondda, Cynon and Merthyr valleys are lined with stone terraces built for mining families, stepped along steep hillsides. Pontypridd, Caerphilly and Merthyr Tydfil have Victorian centres, and Bridgend has grown with large modern estates alongside interwar and post-war housing.
Valley terraces commonly need repointing, roof repairs, rendering and window replacement, and loft conversions can add useful space. Newer estate homes often take garage conversions, porches and landscaping.
These patterns matter for a single-storey extension: older walls, roofs and floors in Caerphilly can need different materials or extra preparation compared with newer homes.
Permissions for a single-storey extension in Caerphilly
England, Wales, Scotland and Northern Ireland each handle planning a little differently. Caerphilly comes under Wales, covered below, and we raise any questions with the council before your quote is finalised.
In Wales, permitted development allows many single-storey rear extensions, with depth and height limits that depend on the type of house and how close the extension comes to your boundaries. Side extensions, listed buildings, conservation areas and flats usually need planning permission.
Building Regulations in Wales apply to extensions, from foundations to insulation and fire safety. The Party Wall etc. Act 1996 applies in Wales as it does in England.
Rules change and every property is different, so we check the planning history and constraints for your address before we quote.
How does the job run?
Free site survey
A free survey comes first. It gives us what we need to price a single-storey extension properly, including dimensions, existing materials and access for deliveries, and gives you the chance to ask anything you like.
Written quote
You get the price in writing, itemised so you can see where the money goes. As long as the specification stays the same, that is the price you pay for a single-storey extension.
Dates and permissions
With the quote agreed, we book the work in and handle preparation: permissions where needed, building control notifications, material orders and access arrangements for your Caerphilly property.
Finish and handover
Work goes ahead as scheduled and you deal with one contact throughout. When the last trade leaves, we clear and clean the site, talk you through what has been done and pass on any certificates and care instructions.
Working with SK Home Improvements
Questions about a single-storey extension in Caerphilly
Can we stay at home during the build?
Most people stay at home while we build a single-storey extension, because the new structure goes up outside before we break through. The disruptive part is usually the last few weeks, when we open into the house and fit the kitchen. We put up dust screens, keep a safe route through the house and agree a temporary kitchen setup if needed. Water and power are only off for short, planned periods.
Can I stay at home during the work?
In most cases, yes. Most people can live at home throughout, and we plan the work to keep disruption down by protecting floors, agreeing working hours and keeping access routes clear. Bigger jobs affecting kitchens, bathrooms or heating may mean a short spell with reduced facilities, and we talk this through with you at the survey.
Do you cover Risca, Pontypridd and Gelligaer?
Yes. As well as Caerphilly, we cover Risca, Pontypridd and Gelligaer and the rest of Mid Glamorgan. Our coverage is UK-wide, so the process is the same wherever you are: a free site survey, a quote in writing that fixes the price for the agreed scope, and one point of contact while the work is planned and carried out.
Do I need planning permission for a single-storey extension?
Whether you need planning permission depends on the extension's size and height, how close it is to boundaries, your home's location, whether it is listed or in a conservation area, and which UK nation you live in. In England, many rear extensions up to 3m deep on a semi or terrace, or 4m on a detached house, can be built under permitted development. We check the rules that apply to your home before quoting.
How much does a single-storey extension cost?
A typical single-storey rear extension of 15–25m² costs £32,000–£69,000, built to a plastered finish ready for your kitchen and decoration. As a guide, allow roughly £1,600–£2,800 per square metre plus fixed costs for groundworks, steelwork and fees. Smaller extensions cost more per square metre. The kitchen, flooring and large glazed doors are usually the biggest extras. We confirm a fixed price for the agreed specification after the survey.
Also covering areas around Caerphilly
We survey and quote throughout Caerphilly's CF83 postcodes and in surrounding places such as Risca, Pontypridd and Gelligaer. The process and pricing approach are identical in each of them.