Mountain Ash, South Wales Valleys
Wraparound extension in Mountain Ash
We plan and build wraparound extensions for homeowners in Mountain Ash. An L-shaped extension that fills the side return and runs across the back. Start with a free site visit, then a written price once the design is agreed.
Mountain Ash is covered from our South Wales Valleys round, including CF43 and CF45. In Mountain Ash we usually draw the wraparound and a simpler rear-only option side by side, so the planning risk and cost difference are clear.
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 wraparound extension cost in Mountain Ash?
For Mountain Ash we work from the Wales rate: £2,050–£3,350 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 |
|---|---|
| L-shaped, about 22 m² of new floor | £45,000–£73,500 |
| L-shaped, about 30 m² of new floor | £61,500–£100,500 |
Your written price follows a measured survey and an agreed design, so it reflects your house, not an average.
Do you need planning permission for a wraparound extension in Mountain Ash?
Here is how the rules in Wales apply to a wraparound extension in Mountain Ash.
Welsh side-extension rules limit a single-storey side addition to 4 metres high and a 50% increase in the width of the original house, with tighter limits in conservation areas. Wraparounds usually need a planning application.
In Wales, as in England, the Party Wall etc. Act 1996 requires notice to neighbours before work to a shared wall or excavation near their foundations.
Conservation areas, National Parks and National Landscapes restrict permitted development in Wales, and listed buildings need listed building consent. Before any drawing we look up the property's history with the council, because earlier extensions and removed rights change the answer.
What are homes in Mountain Ash like to extend?
Stone terraces along the valley floors and post-war semis higher up are typical of Mountain Ash. Sloping sites are common, so floor levels and retaining walls are designed at the start.
How a wraparound extension in Mountain Ash comes together
Free site visit
We measure the house and garden, look at the back wall, drainage and boundaries, and talk through what you want from the space.
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.
Wraparound extensions near Mountain Ash
We also build wraparound extensions in nearby Treharris (3.4 miles) and Rhondda (3.4 miles).
- Wraparound extension in Treharris
- Wraparound extension in Rhondda
- Wraparound extension in Aberdare
- Wraparound extension in Merthyr Tydfil
- Wraparound extension in Nelson
Other work in Mountain Ash:
FAQ
Wraparound extension questions in Mountain Ash
How long does a rear extension take to build in Mountain Ash?
Most single-storey rear extensions take 10 to 16 weeks on site and two-storey extensions 16 to 26 weeks, after design and approvals.
Do I need planning permission for a rear extension in Mountain Ash?
Often not for a single-storey rear extension of up to 4 metres under Welsh permitted development. Wales has no prior approval route for deeper extensions.
Will it take a lot of garden?
Less than a deep rear extension of the same area, because part of the space comes from the side passage.
Is the site visit in Mountain Ash free?
Yes. We visit, measure up and talk through the options with no cost and no obligation.
Will I need a structural engineer?
Yes for the beam over the new opening and usually the foundations; we arrange them and their calculations go to building control.
What postcode areas do you cover around Mountain Ash?
Including CF43 and CF45, and the surrounding South Wales Valleys area.