Two-storey extensions for semi-detached houses in Brynna
Want to stay in Brynna but need more space? A two-storey extension for a semi-detached house adds floor area on two levels without giving up much garden. Here's what's involved.
The basics for Brynna at a glance.
- Postcode districts
- CF35
- County / area
- Mid Glamorgan, Wales
- Price region
- Wales
- Guide price
- £51,500–£69,500 (£1,840–£2,480 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
- Llanharan (1.1 miles), Pencoed (1.9 miles), Pontyclun (3.3 miles)
- Distance to Rhondda
- about 8.4 miles
- First visit
- Free, no obligation
About a two-storey extension for a semi-detached house
A two-storey extension for a semi-detached house is a two-floor addition to the rear, the open side, or both, designed around the attached neighbour on one side. The rear is often the simplest option and can sometimes be permitted development, while a side extension uses the gap on the detached side. Both need care with the shared party wall and the neighbour's light.
Brynna sits about 8.4 miles from Rhondda. Closer to home, Llanharan is 1.1 miles away and Pencoed 1.9 miles.
What it costs in Brynna
Our guide for Wales is £1,840–£2,480 per m² including VAT. On a project with a 4 m × 3.5 m footprint on two floors (28 m² of new floor space), that puts a two-storey extension for a semi-detached house in Brynna at roughly £51,500–£69,500. These are guides, not quotes. Ground conditions, steelwork and access can move the figure either way.
| Spec | Per m² | A 4 m × 3.5 m footprint on two floors (28 m² of new floor space) |
|---|---|---|
| Essential | £1,690–£2,290 per m² | £47,500–£64,000 |
| Standard | £1,840–£2,480 per m² | £51,500–£69,500 |
| Premium | £2,210–£2,980 per m² | £62,000–£83,500 |
Planning and building regulations in Brynna
In Wales, a semi can take a two-storey rear extension under permitted development with the ground floor up to 4 m and the first floor up to 3 m beyond the original rear wall, 10.5 m from the rear boundary. A side extension can also be permitted development if it is 10.5 m from the side boundary, set back 1 m and adds no more than 50% width. 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 Brynna homes
The attached neighbour's light
A two-storey rear extension next to the party wall can take light from the neighbour's rear windows. Councils often use a 45-degree test, so the first floor may need to be shorter than the ground floor or set in from the shared boundary.
Rear, side or both
On a semi, a rear extension sits against the attached neighbour, while a side extension faces the detached neighbour and the street. We compare the space, cost and approval route for each, and for a wraparound, before you commit to one design.
How we'd run your project
Free site visit
We visit your home in Brynna, look at the structure, access and boundaries, and talk through what you want the new rooms to do.
Design and approvals
We draw the extension and check it against the rules for Wales, then apply for planning permission or a certificate of lawfulness, whichever fits.
Price it properly
Once the engineer's calculations are in, we fix the build price in writing, with a clear list of what's included.
Build
Foundations, walls, floor, roof, windows, then first and second fix. We break through into the house as late as we can.
Questions about two-storey extensions for semi-detached houses in Brynna
How much does a two-storey extension for a semi-detached house cost in Brynna?
Our guide for Wales, which covers Brynna, is £1,840–£2,480 per m² including VAT. A typical project with a 4 m × 3.5 m footprint on two floors (28 m² of new floor space) comes to about £51,500–£69,500. Design and approval fees are extra, and we fix the build price in writing once the design is agreed.
Do I need planning permission for a two-storey extension for a semi-detached house in Brynna?
Brynna is in Wales, so Wales planning rules apply. 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. If in doubt, a lawful development certificate or a planning application gives you certainty before you build.
Which postcodes do you cover around Brynna?
We cover Brynna (CF35) and nearby places including Llanharan, Pencoed and Pontyclun, plus the rest of Mid Glamorgan. The first site visit is free.
What if my neighbour has already extended?
That often helps. An existing extension next door can reduce the effect of yours on their light, and may show what the council accepts on your street. It can also mean building alongside their wall, so we check its position, foundations and any windows facing your plot at the survey.
Will a side extension make my semi look like a terrace?
It can if it fills the whole gap to the boundary at first floor and the neighbour does the same. Many councils ask for a first-floor gap to the side boundary or a set-back for this reason. We design the extension to keep the semi reading as one of a pair.
Nearby
Nearby towns we cover for two-storey extensions for semi-detached houses:
Other extensions in Brynna
- Rear
- Side
- Wraparound
- Part two-storey
- Over a garage
- First floor
- Detached
- Kitchen and bedrooms
- Bedroom and en-suite
All two-storey extension services in Brynna · Two-storey extensions for semi-detached houses across Mid Glamorgan
Book a free site visit in Brynna and we'll tell you what's possible, what approvals you need and what the design stage would cost.