Mountain Ash, South Wales Valleys
Glazed rear extension in Mountain Ash
Glazed rear extension in Mountain Ash: full-height glass, slim frames and big rooflights for the most open rear room. We measure the house, show you what the rules allow, price it in writing and build it.
Mountain Ash is covered from our South Wales Valleys round, including CF43 and CF45. A wide sliding door with one long rooflight, rather than a fully glazed roof, keeps a glass-led extension usable in summer.
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 glazed rear extension cost in Mountain Ash?
A glazed rear extension in Mountain Ash is priced at £2,600–£4,460 per square metre including VAT as a guide, before kitchen fit-out and fees. 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) | £31,000–£53,500 |
| 4 m wide × 6 m deep (24 m²) | £62,500–£107,000 |
We put a fixed price in writing once the design is agreed, and explain any provisional sums such as foundations.
Do you need planning permission for a glazed rear extension in Mountain Ash?
Here is how the rules in Wales apply to a glazed rear extension in Mountain Ash.
In Wales a single-storey rear extension can often be permitted development if it projects no more than 4 metres beyond the rear wall and is no more than 4 metres high. Wales has no prior approval route for deeper extensions, so anything bigger needs a householder planning application.
Wales has its own Approved Document L, with targets for walls, roofs, floors and glazing similar to but not identical with England's. Heavily glazed designs are checked with a calculation.
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 glazed rear 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.
Glazed rear extensions near Mountain Ash
From Mountain Ash, the nearest places we also cover are Treharris (3.4 miles) and Rhondda (3.4 miles).
- Glazed rear extension in Treharris
- Glazed rear extension in Rhondda
- Glazed rear extension in Aberdare
- Glazed rear extension in Merthyr Tydfil
- Glazed rear extension in Nelson
Other work in Mountain Ash:
FAQ
Glazed rear extension questions in Mountain Ash
How much does a glazed rear extension cost in Mountain Ash?
As a guide, £2,600–£4,460 per square metre including VAT for a standard specification. For example, 3 m wide × 4 m deep (12 m²): about £31,000–£53,500 at that rate. Your written price follows the survey.
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.
Sliding or bifold doors?
Sliders give bigger panes and slimmer sightlines; bifolds open the whole width. Our guide compares them.
Do you handle building control in Mountain Ash?
Yes. We apply to the council or a registered approver under the Welsh regulations and hand over the completion certificate.
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.
Can you match the brick or stone on my Mountain Ash house?
We source the closest match and show you samples before ordering; reclaimed materials are often the best match on older houses.