Cardiff and the Vale
Glazed and glass-box rear extensions in Cardiff and the Vale
Full-height glass, slim frames and big rooflights for the most open rear room. Rear extensions in Cardiff and the Vale: we cover 6 towns including Cardiff, Barry and Penarth, with design, approvals and the build under one contract.
A wide sliding door with one long rooflight, rather than a fully glazed roof, keeps a glass-led extension usable in summer. Cardiff and the Vale has Victorian terraces near the centre and semis further out. Welsh permitted development allows up to 4 metres at the rear for many houses.
How much does a glazed rear extension cost in Cardiff and the Vale?
In Cardiff and the Vale, our guide for a glazed rear extension is £2,600–£4,460 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) | £31,000–£53,500 |
| 4 m wide × 6 m deep (24 m²) | £62,500–£107,000 |
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 in Cardiff and the Vale?
Welsh permitted development allows a single-storey rear extension of up to 4 metres in depth and 4 metres in height, subject to boundary and garden-coverage limits. There is no larger-extension prior approval scheme in Wales.
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.
Where in Cardiff and the Vale do we work?
FAQ
Questions people ask
Will a glass extension be too hot?
Not if it is designed for its orientation, with solar-control glass, shading and ventilation.
Sliding or bifold doors?
Sliders give bigger panes and slimmer sightlines; bifolds open the whole width. Our guide compares them.
Can I have a level threshold?
Yes, with a drainage channel outside the doors and the slab set to the patio level.
Do you cover all of Cardiff and the Vale?
We cover 6 towns and districts in Cardiff and the Vale, including Cardiff, Barry and Penarth.
Who builds the extension?
Vetted building teams working under contract to us; your contract is with S&K Property Investments and Improvement Ltd.