Treharris, South Wales Valleys
Side return extension in Treharris
We plan and build side return extensions for homeowners in Treharris. Infilling the narrow passage beside a Victorian or Edwardian back addition. Start with a free site visit, then a written price once the design is agreed.
Treharris sits in the South Wales Valleys, with postcode districts including CF46. Side returns suit the Victorian and Edwardian terraces found across parts of the South Wales Valleys, where the kitchen sits in a narrow back addition.
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 side return extension cost in Treharris?
For Treharris we work from the Wales rate: £2,140–£3,530 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 |
|---|---|
| 2 m wide × 6 m deep (12 m²) | £25,500–£42,500 |
| 2.5 m wide × 7 m deep (17.5 m²) | £37,500–£62,000 |
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 side return extension in Treharris?
The planning route for a side return extension in Treharris is set by Wales's householder rules and your council.
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 Treharris like to extend?
Stone terraces along the valley floors and post-war semis higher up are typical of Treharris. Sloping sites are common, so floor levels and retaining walls are designed at the start.
How a side return extension in Treharris 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.
Design and guide price
Two or three layout options with a guide price for each, so you choose the design knowing what it costs.
Paperwork handled
Planning or permitted development, Building Regulations approval, structural design and party wall notices are all handled by us.
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.
Side return extensions near Treharris
From Treharris, the nearest places we also cover are Nelson (1.2 miles) and Gelligaer (2.2 miles).
- Side return extension in Nelson
- Side return extension in Gelligaer
- Side return extension in Mountain Ash
- Side return extension in Bargoed
- Side return extension in Blackwood
Other work in Treharris:
FAQ
Side return extension questions in Treharris
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.
Who will build my extension?
Vetted building teams working under contract to us. Your contract is with S&K Property Investments and Improvement Ltd for the design and the build.
Glass roof or solid roof with rooflights?
A glass roof gives the most light; a solid roof with long rooflights is warmer and quieter in rain. Both work.
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.
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 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.