Blackwood, South Wales Valleys
Semi-detached rear extension in Blackwood
Single or two-storey extensions for semi-detached houses, with side access and one party wall. If you live in Blackwood and want to know what a semi-detached rear extension would cost and whether it needs planning, start with the online guide price or a free site visit.
Blackwood and its postcode districts NP12 are part of our South Wales Valleys coverage. Semi-detached houses are common across the South Wales Valleys, and their side access makes rear extensions quicker to build.
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 Blackwood?
In Blackwood, our guide for a semi-detached rear extension is £1,770–£2,880 per square metre including VAT for a 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 |
Ground conditions, glazing, the roof and how far the house is opened up move the final figure within the range.
Do you need planning permission for a semi-detached rear extension in Blackwood?
Here is how the rules in Wales apply to a semi-detached rear extension in Blackwood.
Welsh permitted development allows a single-storey rear extension of up to 4 metres in depth and 4 metres in height, subject to boundary and garden-coverage limits. There is no larger-extension prior approval scheme in Wales.
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 Blackwood like to extend?
Stone terraces along the valley floors and post-war semis higher up are typical of Blackwood. Sloping sites are common, so floor levels and retaining walls are designed at the start.
How a semi-detached rear extension in Blackwood comes together
Survey visit
We visit free of charge, measure up, check access, drainage and neighbours' extensions, and note what you want the room to do.
Design and guide price
Two or three layout options with a guide price for each, so you choose the design knowing what it costs.
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.
Build and sign-off
We build to the approved drawings with regular updates, then hand over the building control completion certificate and any guarantees from suppliers.
Semi-detached rear extensions near Blackwood
From Blackwood, the nearest places we also cover are Bargoed (1.5 miles) and Gelligaer (2.1 miles).
- Semi-detached rear extension in Bargoed
- Semi-detached rear extension in Gelligaer
- Semi-detached rear extension in Abercarn
- Semi-detached rear extension in Nelson
- Semi-detached rear extension in Treharris
Other work in Blackwood:
FAQ
Semi-detached rear extension questions in Blackwood
Can I live at home while the extension is built?
Usually yes. Most of the work is outside until the back wall is opened near the end, and that stage is screened off.
What postcode areas do you cover around Blackwood?
Including NP12, and the surrounding South Wales Valleys area.
Can I match pebbledash or render?
Yes. Many semis are refinished with new render across the whole back elevation so old and new match.
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 Blackwood 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 Blackwood free?
Yes. We visit, measure up and talk through the options with no cost and no obligation.