St Helens, Merseyside
Glazed rear extension in St Helens
Glazed rear extension in St Helens: full-height glass, slim frames and big rooflights for the most open rear room. We measure the house, show you what the rules allow, price it in writing and build it.
We cover St Helens (WA9, WA10 and WA11) as part of our Merseyside work. 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 Helens?
For St Helens we work from the North West England rate: £2,630–£4,510 per square metre of new floor, including VAT, standard specification. North West prices sit below our West Midlands baseline; access on terraced streets is the main variable.
| Size | Guide price inc VAT |
|---|---|
| 3 m wide × 4 m deep (12 m²) | £31,500–£54,000 |
| 4 m wide × 6 m deep (24 m²) | £63,000–£108,500 |
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 glazed rear extension in St Helens?
The planning route for a glazed rear extension in St Helens 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 Helens like to extend?
Stone and brick terraces are common around St Helens. Where houses back onto a ginnel or alley, deliveries can come in from the rear, which makes the build tidier.
How a glazed rear extension in St Helens 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.
Options and costs
We draw layout options and price each one, so the budget shapes the design rather than surprising you later.
Approvals
Permitted development check, prior approval or planning application, then Building Regulations drawings and structural calculations, plus party wall notices where they apply.
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 Helens
Neighbouring places we cover include Haydock (2.4 miles) and Rainhill (2.7 miles).
- Glazed rear extension in Haydock
- Glazed rear extension in Rainhill
- Glazed rear extension in Whiston
- Glazed rear extension in Prescot
- Glazed rear extension in Ashton in Makerfield
Other work in St Helens:
FAQ
Glazed rear extension questions in St Helens
Is the site visit in St Helens free?
Yes. We visit, measure up and talk through the options with no cost and no obligation.
Do you handle building control in St Helens?
Yes. We apply to the council or a registered building control approver and hand over the completion certificate.
Does glass need planning permission?
The same rules apply as any rear extension; glass does not change the depth or height limits.
Do I need planning permission for a rear extension in St Helens?
Often not for a single-storey rear extension of up to 3 metres (4 metres on a detached house) under permitted development, or up to 6 or 8 metres with prior approval, unless the house is in a conservation area or its rights have been removed.
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.
What postcode areas do you cover around St Helens?
Including WA9, WA10 and WA11, and the surrounding Merseyside area.