Penzance, Cornwall
Glazed rear extension in Penzance
Full-height glass, slim frames and big rooflights for the most open rear room. If you live in Penzance and want to know what a glazed rear extension would cost and whether it needs planning, start with the online guide price or a free site visit.
We cover Penzance (TR18) as part of our Cornwall work. If your garden in Penzance faces south, expect us to talk about overhangs and solar-control glass before frame colours.
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 Penzance?
For Penzance we work from the South West England rate: £2,910–£4,990 per square metre of new floor, including VAT, standard specification. 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 |
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 glazed rear extension in Penzance?
Planning for a glazed rear extension in Penzance follows the English householder rules.
Under England's householder permitted development rules you can usually add 3 metres at the back of an attached house, or 4 metres on a detached house, without a planning application, as long as the extension stays under 4 metres high and its eaves stay under 3 metres where it 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. At the first visit we measure what is there now and tell you which route fits: permitted development, prior approval or a planning application.
What are homes in Penzance like to extend?
Penzance 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 Penzance 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.
Drawings and budget
Floor plans and elevations for the options, each with a guide price.
Paperwork handled
Planning, prior approval 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.
Glazed rear extensions near Penzance
Close by, we work in Helston, about 11.9 miles away, and Camborne, about 12.5 miles away.
- Glazed rear extension in Helston
- Glazed rear extension in Camborne
- Glazed rear extension in Redruth
- Glazed rear extension in Falmouth
- Glazed rear extension in Truro
Other work in Penzance:
FAQ
Glazed rear extension questions in Penzance
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.
How much does a glazed rear extension cost in Penzance?
As a guide, £2,910–£4,990 per square metre including VAT for a standard specification. For example, 3 m wide × 4 m deep (12 m²): about £35,000–£60,000 at that rate. Your written price follows the survey.
Is a glass box a conservatory?
No. It is built to Building Regulations as part of the house, with insulated floor and roof, so it is usable all year.
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.
Do you handle building control in Penzance?
Yes. We apply to the council or a registered building control approver and hand over the completion certificate.
What postcode areas do you cover around Penzance?
Including TR18, and the surrounding Cornwall area.