Gelligaer, South Wales Valleys
Semi-detached rear extension in Gelligaer
Single or two-storey extensions for semi-detached houses, with side access and one party wall. We design, get the approvals for and build rear extensions for semi-detached houses in Gelligaer and the surrounding area, with one contract from the first survey to building control sign-off.
We cover Gelligaer (CF82) as part of our South Wales Valleys work. 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 Gelligaer?
In Gelligaer, 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 Gelligaer?
Whether your semi-detached rear extension in Gelligaer needs a planning application depends on its size, your house and any local restrictions.
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.
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. 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 Gelligaer like to extend?
Gelligaer is largely terraced streets on sloping ground, where back gardens step up or down from the house. Excavation, retaining walls and drainage are priced at the survey.
How a semi-detached rear extension in Gelligaer 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.
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.
Semi-detached rear extensions near Gelligaer
Neighbouring places we cover include Nelson (1.4 miles) and Bargoed (1.6 miles).
- Semi-detached rear extension in Nelson
- Semi-detached rear extension in Bargoed
- Semi-detached rear extension in Blackwood
- Semi-detached rear extension in Treharris
- Semi-detached rear extension in Abercarn
Other work in Gelligaer:
FAQ
Semi-detached rear extension questions in Gelligaer
Is the site visit in Gelligaer free?
Yes. We visit, measure up and talk through the options with no cost and no obligation.
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.
Do I need a party wall agreement?
Usually with the attached neighbour, in England and Wales.
How much does a semi-detached rear extension cost in Gelligaer?
As a guide, £1,770–£2,880 per square metre including VAT for a standard specification. For example, 3 m wide × 4 m deep (12 m²): about £21,000–£34,500 at that rate. Your written price follows the survey.
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.
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.