St Helens, Merseyside
Two-storey rear extension in St Helens
A larger kitchen downstairs and an extra bedroom or bathroom upstairs, under one roof. If you live in St Helens and want to know what a two-storey rear extension would cost and whether it needs planning, start with the online guide price or a free site visit.
St Helens is covered from our Merseyside round, including WA9, WA10 and WA11. In St Helens, a two-storey rear extension is worth comparing with the cost of moving once stamp duty, agents' and legal fees are counted.
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 two-storey rear extension cost in St Helens?
For St Helens we work from the North West England rate: £1,690–£2,540 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 × 5 m footprint, two floors (30 m²) | £51,000–£76,000 |
| 4 m × 6 m footprint, two floors (48 m²) | £81,000–£122,000 |
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 two-storey rear extension in St Helens?
Here is how the rules in England apply to a two-storey rear extension in St Helens.
A two-storey rear extension can be permitted development in England only if it projects no more than 3 metres, stays at least 7 metres from the rear boundary, matches the existing roof pitch and has obscure-glazed upper side windows. In practice most double-storey rear extensions go through a householder planning application.
Conservation areas, National Parks, National Landscapes and the Broads restrict permitted development, and listed buildings always need listed building consent. Before any drawing we look up the property's history with the council, because earlier extensions and removed rights change the answer.
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 two-storey 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.
Drawings and budget
Floor plans and elevations for the options, each with a guide price.
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.
Two-storey rear extensions near St Helens
We also build two-storey rear extensions in nearby Haydock (2.4 miles) and Rainhill (2.7 miles).
- Two-storey rear extension in Haydock
- Two-storey rear extension in Rainhill
- Two-storey rear extension in Whiston
- Two-storey rear extension in Prescot
- Two-storey rear extension in Ashton in Makerfield
Other work in St Helens:
FAQ
Two-storey rear extension questions in St Helens
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.
Can I live at home while the extension is built?
Usually yes. Most of the work is outside until the back wall is opened near the end, and that stage is screened off.
Will we need to move out?
Rarely. The first-floor opening is made late in the job and sealed with temporary screens.
How long does a rear extension take to build in St Helens?
Most single-storey rear extensions take 10 to 16 weeks on site and two-storey extensions 16 to 26 weeks, after design and approvals.
What postcode areas do you cover around St Helens?
Including WA9, WA10 and WA11, and the surrounding Merseyside area.
Is the site visit in St Helens free?
Yes. We visit, measure up and talk through the options with no cost and no obligation.