St Helens at a glance
- Postcode districts
- L35, WA9, WA10, WA11, WA12
- Population
- about 183,200 (GeoNames)
- Council area
- St Helens Borough Council
- Building approval
- St Helens Borough Council building control, or a registered building control approver
- Nearest main town
- Liverpool, about 10 miles
- Guide price region
- North West (−5% on West Midlands rates)
Why choose a green roof in St Helens?
If you're replacing an old flat roof in St Helens, it's worth deciding whether to add sedum at the same time. If the structure can take it, that is the ideal moment, because the waterproofing is new and the green layers won't need lifting for a long time.
Around St Helens, flat roofs are common on 1930s semis with flat-roofed garages and kitchen extensions and on shops with flat-roofed rear stores below flats. The North West is one of England's wetter regions, averaging roughly 1,290 mm of rain a year, so falls, outlets and well-detailed upstands matter more than the membrane colour.
How much does a green roof cost in St Helens?
At North West guide rates, a 20 m² insulated extension roof finished as a sedum green roof comes to £4,200–£7,700 including VAT. The fixed price comes after a free survey for new and replacement roofs.
| Job | Guide price inc VAT |
|---|---|
| Extension (20 m²), EPDM with sedum green roof | £4,200–£7,700 |
| Extension (20 m²), EPDM, new deck + insulation | £2,650–£4,650 |
Can my flat roof take the weight of a green roof?
Not every roof can, which is why we check the structure before quoting. A sedum roof is light compared with an intensive garden, but its growing medium holds water, and a saturated build-up adds significant weight to the roof.
We look at the joist sizes, spans and spacing, the condition of the deck and what the roof sits on. On a recently built extension with generously sized joists, an extensive green roof may be straightforward. On an older garage or a roof with undersized or rotten timbers, the structure may need strengthening, or a structural engineer's calculation may be needed before we can go ahead.
In England, a new roof covering that adds 15% or more to the weight of the roof triggers building control approval, and a green roof will often fall into that category. We handle building control where it is needed. The building regulations page covers the approval routes in each nation.
What's included?
- Pre-grown sedum blankets laid and watered in
- Warm or inverted build-up to suit the roof
- Structural check of joists, deck and supports
- Gravel strips kept clear around edges and outlets
Building regulations in England
Replacing more than half of a flat roof over a heated room usually counts as renovating a thermal element, so the roof is insulated to around 0.16 W/m²K where that's technically and economically feasible, and the work is notified to building control: the council or a registered building control approver, unless a registered competent person self-certifies it. A roof on a new extension is built to 0.15 W/m²K. Patch repairs, and most unheated detached garages, don't trigger the upgrade. Structural changes, or a new covering that adds 15% or more to the roof's weight, also need approval. More on the rules.
Which nearby areas do we also cover?
- Haydock · 2 mi
- Prescot · 3 mi
- Ashton in Makerfield · 4 mi
- Huyton · 5 mi
- Newton-le-Willows · 5 mi
- Great Sankey · 6 mi
Green and sedum roofs in St Helens: questions
Do you cover St Helens?
Yes. St Helens is part of our Merseyside coverage, including postcode districts L35, WA9, WA10, WA11, WA12. Surveys and roofs are carried out by vetted roofing teams working under S&K Property Investments and Improvement Ltd.
Who checks building regulations for a flat roof in St Helens?
Where the work needs approval it goes to St Helens Borough Council building control, or a registered building control approver. We tell you at the survey whether your job needs it and deal with the paperwork as part of the quote.
How much does a green roof cost in St Helens?
£4,200–£7,700 for a 20 m² insulated extension roof finished as a sedum green roof, at North West guide rates including VAT. The fixed price comes after a free survey for new and replacement roofs.
Can I walk on a green roof?
Only for maintenance, and only where it is safe. Most extensive green roofs on homes aren't designed as roof terraces, and a terrace generally needs planning permission and edge protection.
Can a green roof have a rooflight in it?
Yes. The rooflight sits on a raised upstand with a gravel strip around it, so the planting stays clear of the glazing and the upstand stays visible and dry.