Treharris, South Wales Valleys
Two-storey rear extension in Treharris
For homes in Treharris, a two-storey rear extension is often the simplest way to gain space without moving. A larger kitchen downstairs and an extra bedroom or bathroom upstairs, under one roof. We take it from survey to completion certificate.
Treharris is covered from our South Wales Valleys round, including CF46. Two-storey rear extensions suit semi-detached houses in Treharris best, where the extra bedroom matters as much as the bigger kitchen.
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 two-storey rear extension cost in Treharris?
In Treharris, our guide for a two-storey rear extension is £1,670–£2,510 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 × 5 m footprint, two floors (30 m²) | £50,000–£75,500 |
| 4 m × 6 m footprint, two floors (48 m²) | £80,500–£120,500 |
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 two-storey rear extension in Treharris?
Whether your two-storey rear extension in Treharris needs a planning application depends on its size, your house and any local restrictions.
Welsh rules allow a two-storey rear extension without an application only where the ground floor is no deeper than 4 metres, the upper floor no deeper than 3 metres and at least 10.5 metres remains to the rear boundary. Most homeowners still apply for householder planning permission.
Conservation areas, National Parks and National Landscapes restrict permitted development in Wales, and listed buildings need listed building consent. At the first visit we measure what is there now and tell you which route fits: permitted development or a householder planning application.
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 two-storey rear 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.
Written price, then build
Once the design and approvals are in place, you get a fixed written price and programme, and we build through to sign-off.
Two-storey rear extensions near Treharris
From Treharris, the nearest places we also cover are Nelson (1.2 miles) and Gelligaer (2.2 miles).
- Two-storey rear extension in Nelson
- Two-storey rear extension in Gelligaer
- Two-storey rear extension in Mountain Ash
- Two-storey rear extension in Bargoed
- Two-storey rear extension in Blackwood
Other work in Treharris:
FAQ
Two-storey rear extension questions in Treharris
Can you match the brick or stone on my Treharris house?
We source the closest match and show you samples before ordering; reclaimed materials are often the best match on older houses.
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.
Does a two-storey rear extension need planning permission?
Almost always. England and Northern Ireland allow 3 metres without an application only if at least 7 metres remains to the rear boundary; Wales and Scotland are similar or stricter.
Is the site visit in Treharris free?
Yes. We visit, measure up and talk through the options with no cost and no obligation.
What postcode areas do you cover around Treharris?
Including CF46, and the surrounding South Wales Valleys area.
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.