Two-storey extensions for detached houses in Llantrisant
Adding a two-storey extension for a detached house in Llantrisant gives you two new rooms stacked on one footprint. Here's how we'd approach it, what it typically costs and the rules that apply in Wales.
Llantrisant: the key facts for this kind of project.
- Postcode districts
- CF72
- County / area
- Mid Glamorgan, Wales
- Price region
- Wales
- Guide price
- £79,000–£106,500 (£1,890–£2,530 per m²)
- Approval route
- Depends on position: rear (3 m first floor, 10.5 m to the boundary) and some side extensions (10.5 m, 1 m set-back) can be permitted development in Wales.
- Nearest towns
- Beddau (1.2 miles), Pontyclun (1.5 miles), Llanharan (2.8 miles)
- Distance to Rhondda
- about 8.8 miles
- First visit
- Free, no obligation
About a two-storey extension for a detached house
This service suits you if you own a detached house and want a substantial amount of extra space, whether a side extension over a drive, a rear extension into the garden or a wraparound. You get a survey of the whole plot, options that compare layouts and costs, the approvals your nation needs, structural design and the build, carried out by vetted teams working under S&K.
Llantrisant sits about 8.8 miles from Rhondda. Closer to home, Beddau is 1.2 miles away and Pontyclun 1.5 miles.
What it costs in Llantrisant
Our guide for Wales is £1,890–£2,530 per m² including VAT. On a project with a 3 m × 7 m footprint on two floors (42 m² of new floor space), that puts a two-storey extension for a detached house in Llantrisant at roughly £79,000–£106,500. Steelwork for wide openings is the item most likely to move the figure; we'll know once the engineer has designed it.
| Spec | Per m² | A 3 m × 7 m footprint on two floors (42 m² of new floor space) |
|---|---|---|
| Essential | £1,740–£2,330 per m² | £73,000–£98,000 |
| Standard | £1,890–£2,530 per m² | £79,000–£106,500 |
| Premium | £2,260–£3,040 per m² | £95,000–£127,500 |
Planning and building regulations in Llantrisant
In Wales, detached houses are more likely to meet the permitted development tests for a two-storey side extension: 10.5 m to the boundary opposite the side wall, a 1 m set-back from the front and no more than 50% added width. Rear permitted development allows 4 m on the ground floor and 3 m on the first floor. Otherwise the fee is £585.
Approval in Wales: Householder planning application: £585. Councils normally decide householder applications within 8 weeks.
Building regulations: Building regulations approval under the Welsh Approved Documents, which differ from England's in places (notably energy efficiency).
Design points for Llantrisant homes
Choosing the best side
On a detached house you can often extend on either side or the rear. We look at orientation for daylight, where the stairs and landing are, the distance to each boundary, drains and trees, so the extension goes where it adds the most useful space.
Gaps to boundaries
Detached houses are often defined by the space around them. Keeping a gap to the side boundary at first floor maintains that character, helps planning and leaves access to the rear garden. In Wales the 10.5 m side distance decides whether permitted development applies.
How we'd run your project
Free site visit
We visit your home in Llantrisant, look at the structure, access and boundaries, and talk through what you want the new rooms to do.
Drawings and permission
Our designers produce plans and elevations, then we take care of planning or permitted development checks with the council covering Llantrisant.
Detail and price
Construction drawings, engineer's calculations and building control sign-off, then a written fixed price for the build.
Build it
The new structure goes up first, then we open into the house, finish inside and get the completion certificate.
Questions about two-storey extensions for detached houses in Llantrisant
How much does a two-storey extension for a detached house cost in Llantrisant?
Our guide for Wales, which covers Llantrisant, is £1,890–£2,530 per m² including VAT. A typical project with a 3 m × 7 m footprint on two floors (42 m² of new floor space) comes to about £79,000–£106,500. Design and approval fees are extra, and we fix the build price in writing once the design is agreed.
How long does a two-storey extension for a detached house take?
Allow 4 to 8 weeks for survey and design, then the approval period (councils normally decide householder applications within 8 weeks), then 4 to 8 weeks of technical design, which can overlap. The build itself usually takes 14 to 20 weeks, longer for large or complex designs.
Which postcodes do you cover around Llantrisant?
We cover Llantrisant (CF72) and nearby places including Beddau, Pontyclun and Llanharan, plus the rest of Mid Glamorgan. The first site visit is free.
Is a detached house extension a better investment than moving?
It often costs less than the gap between your house and a larger one nearby, once property tax, legal fees and removal costs are counted, but that depends on your area. Extending also has limits: every street has a ceiling price. We give you build costs so you can compare them with local asking prices.
Can I extend a detached house on both sides?
Sometimes. With planning permission, a council may accept extensions on both sides if the house stays well proportioned and keeps gaps to the boundaries. It is more common to extend on one side and the rear, or with a wraparound. We look at the plot as a whole before suggesting more than one extension.
Nearby
We also cover places near Llantrisant, including:
Other extensions in Llantrisant
- Rear
- Side
- Wraparound
- Part two-storey
- Over a garage
- First floor
- Semi-detached
- Kitchen and bedrooms
- Bedroom and en-suite
All two-storey extension services in Llantrisant · Two-storey extensions for detached houses across Mid Glamorgan
Book a free site visit in Llantrisant and we'll tell you what's possible, what approvals you need and what the design stage would cost.