Rhiwbina, Cardiff and the Vale
Semi-detached rear extension in Rhiwbina
We plan and build rear extensions for semi-detached houses for homeowners in Rhiwbina. Single or two-storey extensions for semi-detached houses, with side access and one party wall. Start with a free site visit, then a written price once the design is agreed.
Rhiwbina sits in Cardiff and the Vale, with postcode districts including CF14. Where a Rhiwbina semi already has a small lean-to at the back, we usually replace it rather than extend it.
Book a free site visit
Tell us about the house and we'll call to arrange a free, no-obligation visit.
How much does a semi-detached rear extension cost in Rhiwbina?
For Rhiwbina we work from the Wales rate: £1,770–£2,880 per square metre of new floor, including VAT, standard specification. Prices in Wales sit below our West Midlands baseline; sloping sites are the main variable.
| Size | Guide price inc VAT |
|---|---|
| 3 m wide × 4 m deep (12 m²) | £21,000–£34,500 |
| 4 m wide × 5 m deep (20 m²) | £35,500–£57,500 |
| 4 m wide × 6 m deep (24 m²) | £42,500–£69,000 |
These are guide ranges; the written quote after the survey is the figure that counts.
Do you need planning permission for a semi-detached rear extension in Rhiwbina?
Planning for a semi-detached rear extension in Rhiwbina follows the Welsh householder rules.
The Welsh Government's householder rules let many homes add a single-storey rear extension up to 4 metres deep and 4 metres high without a planning application. Deeper projects go through a householder application, because Wales has no prior approval route.
In Wales a rear extension of more than one storey can be permitted development if the ground floor projects no more than 4 metres and the upper floor no more than 3 metres, with at least 10.5 metres to the rear boundary. It is not permitted development in conservation areas, National Parks or National Landscapes, so many double-storey schemes need a householder application.
Conservation areas, National Parks and National Landscapes restrict permitted development in Wales, and listed buildings need listed building consent. We check your house's planning history and any conservation area before drawing, so the route is clear before you spend on plans.
What are homes in Rhiwbina like to extend?
Older terraces near the centre and post-war semis further out are typical of Rhiwbina. Sloping sites are common in Wales, so floor levels and retaining walls are designed at the start. In Rhiwbina we measure the attached neighbour's extension at the survey, because it often sets the sensible depth for yours.
How a semi-detached rear extension in Rhiwbina comes together
Look round and measure
A free visit to see the back of the house, measure it, check the drains and boundaries and hear what you need.
Options and costs
We draw layout options and price each one, so the budget shapes the design rather than surprising you later.
Approvals
Permitted development check or householder planning application, then Building Regulations drawings to the Welsh Approved Documents and structural calculations, plus party wall notices where they apply.
Fixed price and build
A written price for the agreed design, a start date and a named contact through the build, ending with the building control completion certificate.
Semi-detached rear extensions near Rhiwbina
We also build rear extensions for semi-detached houses in nearby Whitchurch (1.2 miles) and Caerphilly (3.2 miles).
- Semi-detached rear extension in Whitchurch
- Semi-detached rear extension in Caerphilly
- Semi-detached rear extension in Cardiff
- Semi-detached rear extension in Penarth
- Semi-detached rear extension in Llantrisant
Other work in Rhiwbina:
FAQ
Semi-detached rear extension questions in Rhiwbina
How much does a semi-detached rear extension cost in Rhiwbina?
As a guide, £1,770–£2,880 per square metre including VAT for a standard specification. For example, 3 m wide × 4 m deep (12 m²): about £21,000–£34,500 at that rate. Your written price follows the survey.
Do I need a party wall agreement?
In Wales, usually yes if the extension is on or near a shared boundary or close to a neighbour's foundations. We serve the notices.
How long does a semi extension take?
10 to 16 weeks on site for a single-storey extension.
Can I get a price without a visit?
Our online guide-price tool gives a range in a couple of minutes. A written price needs a survey.
Can you match the brick or stone on my Rhiwbina house?
We source the closest match and show you samples before ordering; reclaimed materials are often the best match on older houses.
Is the site visit in Rhiwbina free?
Yes. We visit, measure up and talk through the options with no cost and no obligation.