St Albans at a glance
- Postcode districts
- AL1, AL2, AL3
- Population
- about 84,561 (GeoNames)
- Council area
- St Albans City and District Council
- Building approval
- St Albans City and District Council building control, or a registered building control approver
- Nearest main town
- Hemel Hempstead, about 5 miles
- Guide price region
- East of England (+5% on West Midlands rates)
Why choose a green roof in St Albans?
In a place like St Albans, many people look out over a flat extension or garage roof from upstairs. Grey felt or rubber isn't much of a view, and a sedum roof turns it into something green that changes colour through the seasons and flowers in summer.
In a large town like St Albans, flat roofs are commonly found on newer estates where the first extension roofs are now being replaced or terraced streets with flat-roofed rear kitchens and bathrooms. The East of England is the driest part of Britain, with parts of the Anglian region around 630 mm a year, so summer heat and UV, not rainfall, do most of the ageing on a felt roof.
How much does a green roof cost in St Albans?
For St Albans we use East of England rates: £4,650–£8,500 is the guide for a 20 m² insulated extension roof finished as a sedum green roof, VAT included. 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 | £4,650–£8,500 |
| Extension (20 m²), EPDM, new deck + insulation | £2,950–£5,150 |
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?
- Warm or inverted build-up to suit the roof
- Drainage layer, filter and lightweight growing medium
- Pre-grown sedum blankets laid and watered in
- Structural check of joists, deck and supports
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?
- Harpenden · 5 mi
- Hatfield · 5 mi
- Hemel Hempstead · 5 mi
- Welwyn Garden City · 6 mi
- Borehamwood · 7 mi
- Watford · 7 mi
Green and sedum roofs in St Albans: questions
Do you cover St Albans?
Yes. St Albans is part of our Hertfordshire coverage, including postcode districts AL1, AL2, AL3. 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 Albans?
Where the work needs approval it goes to St Albans City and District 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 Albans?
£4,650–£8,500 for a 20 m² insulated extension roof finished as a sedum green roof, at East of England 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.
Do I need to water a sedum roof?
Usually only in the first season, during long dry spells, while the blankets establish. After that, sedum copes with dry weather well.