St Austell, Cornwall
Glazed rear extension in St Austell
Full-height glass, slim frames and big rooflights for the most open rear room. We design, get the approvals for and build glazed and glass-box rear extensions in St Austell and the surrounding area, with one contract from the first survey to building control sign-off.
St Austell is covered from our Cornwall round, including PL25. 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 St Austell?
Guide prices for a glazed rear extension in St Austell start from our South West England rate of £2,910–£4,990 per square metre, including VAT. South West prices run slightly above our West Midlands baseline; natural stone to match the house is the main variable.
| Size | Guide price inc VAT |
|---|---|
| 3 m wide × 4 m deep (12 m²) | £35,000–£60,000 |
| 4 m wide × 6 m deep (24 m²) | £70,000–£120,000 |
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 St Austell?
The planning route for a glazed rear extension in St Austell is set by England's householder rules and your council.
In England a single-storey rear extension can often be built under permitted development: up to 3 metres beyond the original rear wall of an attached house, or 4 metres on a detached house, no higher than 4 metres, with eaves no higher than 3 metres if any part is within 2 metres of a boundary.
New fabric must meet Approved Document L (2021 edition incorporating 2023 amendments): walls 0.18, roof 0.15 and floor 0.18 W/m²K, windows 1.4 W/m²K or Band B. Under the simple route, new windows, doors and rooflights should not exceed 25% of the extension floor area plus any openings removed; more glass is possible with a whole-house calculation.
Conservation areas, National Parks, National Landscapes and the Broads restrict permitted development, and listed buildings always 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 St Austell like to extend?
St Austell has Victorian terraces nearer the centre and post-war semis on the edges. Sloping gardens are frequent, which affects floor levels and steps down to the patio.
How a glazed rear extension in St Austell 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.
Planning and regulations
We take the design through the right planning route, then produce the construction drawings and engineer's calculations for building control.
Build and sign-off
We build to the approved drawings with regular updates, then hand over the building control completion certificate and any guarantees from suppliers.
Glazed rear extensions near St Austell
Close by, we work in Bodmin, about 9.2 miles away, and Truro, about 13.5 miles away.
- Glazed rear extension in Bodmin
- Glazed rear extension in Truro
- Glazed rear extension in Newquay
- Glazed rear extension in Falmouth
- Glazed rear extension in Redruth
Other work in St Austell:
FAQ
Glazed rear extension questions in St Austell
What postcode areas do you cover around St Austell?
Including PL25, and the surrounding Cornwall area.
Can you match the brick or stone on my St Austell house?
We source the closest match and show you samples before ordering; reclaimed materials are often the best match on older houses.
Is there a limit on how much glass I can have?
In England the simple rule is 25% of the floor area plus openings removed; more is allowed with a calculation showing the house still meets Part L.
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?
In England, usually yes if the extension is on or near a shared boundary or the foundations are close to a neighbour's building. We serve the notices.
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.