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.
Whatever type of house you own in Penarth, we start by looking at how a single-storey extension would fit it rather than offering a standard package. We cover CF64 and neighbouring places such as Cardiff, Barry and Caerphilly. One named person looks after you from survey to handover, and nothing is booked until you hold our figure in writing, fixed for the work described.
- Guide price
- £32,000–£69,000 inc VAT
- Time on site
- 10–16 weeks on site
- Postcodes
- CF64
- Planning rules
- Wales
- Local area
- The Vale of Glamorgan
- Survey
- Free, with a written quote
What should you budget for a single-storey extension in Penarth?
What will a single-storey extension cost in Penarth? Our guide range is £32,000–£69,000 including VAT. That figure is adjusted for Wales, about 8% below the national guide, and is intended for planning a budget. A firm written price for your chosen specification follows a free survey at your home.
| Type of job | What it usually involves | Guide in Penarth |
|---|---|---|
| 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 |
Your price depends mostly on:
- Floor area, shape and number of corners
- 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
What does the job include in Penarth?
- 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
- Windows and external doors, including bifolds if chosen
- Plastering, screed floor and internal doors
- Building control inspections and completion certificate
Building in Penarth
Cardiff has large areas of bay-fronted Victorian and Edwardian terraces in districts such as Roath, Canton and Cathays, plus interwar suburbs, post-war estates and modern flats around Cardiff Bay. Penarth has Victorian villas, Barry mixes terraces with newer estates, and Vale of Glamorgan villages are often built of local limestone.
Terraces commonly suit loft conversions, side-return and rear extensions, and bay window renewal. Suburban semis take side extensions and driveways, and stone village homes need lime-based repairs.
With that background in mind, here is how we typically handle a single-storey extension for homes in Penarth, from the first visit to the finished result.
Do you need permission in Penarth?
Homes in Penarth come under the regulations for Wales, summarised below. We don't rely on general rules alone: we confirm the position for your address with the council before a quote goes out.
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.
What happens after you get in touch?
Survey and measure
It starts with a survey at the property, free of charge. We check condition, access and services, ask how you want the finished result to look, and answer any questions you have about a single-storey extension.
Your fixed price
After the survey we send a quote for a single-storey extension that fixes the price for the scope we've agreed. If you want to change materials or scope, we revise it in writing before anything is booked.
Booking the work
Next comes planning the work itself. We set a start date that suits you, line up the right trades, and make sure any approvals for a single-storey extension are in place before the first day on site.
The work itself
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.
Why homeowners choose us
Common questions
Is the price fixed?
Yes, for the specification we agree. Your written quote sets out exactly what is included at a fixed price. It only changes if you ask for something different, or if a problem the survey could not reasonably reveal later needs extra work. In either case we explain the change and confirm it in writing before going ahead.
How long will a single-storey extension take?
On a typical home, allow 10–16 weeks on site. Larger projects, older buildings and extra work found once things are opened up can extend that, while simpler jobs may be shorter. Your quote includes an estimate of time on site, and your point of contact keeps you updated on the programme as the work progresses.
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.
What does a typical extension build look like week by week?
A typical single-storey extension follows the same order: clearing the site and digging foundations, building walls up to roof level, then fitting the roof and windows to make it weathertight. Electrics, plumbing, insulation and plastering follow. The last stage is opening into the house, laying the screed and fitting doors and finishes. Building control inspects at key stages, and we book those visits for you.
How long does a single-storey extension take to build?
A single-storey extension usually takes 10–16 weeks on site, from digging foundations to final plastering. Bad weather, deep foundations or a complex roof can add time. Before work starts, allow several weeks for drawings, structural calculations and building control approval, and longer if planning permission is needed. We give you a stage-by-stage programme with your quote so you know what happens each week.
Also covering areas around Penarth
Coverage for Penarth spans CF64. Close by, Cardiff, Barry and Caerphilly are covered too, and the rest of our UK-wide area follows the same survey-then-quote process from start to finish.