Green and sedum roofs in Amersham

Why choose a green roof in Amersham?

In a place like Amersham, 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.

Amersham's flat roofs are mostly on bungalows with flat-roofed side extensions and dormers, with plenty on 1960s and 1970s link-detached houses with flat-roofed garages and porches too. Much of the South East sits in the drier Thames catchment at roughly 730 mm of rain a year, so the usual failures are at joints, upstands and outlets rather than from sheer volume of rain.

How much does a green roof cost in Amersham?

At South East guide rates, a 20 m² insulated extension roof finished as a sedum green roof comes to £4,850–£8,900 including VAT. The fixed price comes after a free survey for new and replacement roofs.

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
• Gravel strips kept clear around edges and outlets
• Root-resistant membrane or separate root barrier
• Drainage layer, filter and lightweight growing medium

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?

• Chesham · 2 mi
• Chalfont Saint Peter · 5 mi
• Gerrards Cross · 6 mi
• High Wycombe · 6 mi
• Rickmansworth · 6 mi
• Berkhamsted · 7 mi

Other flat roof work in Amersham

• Flats, HMOs and block roofs
• Extension and kitchen roofs
• Flat roof replacement
• EPDM rubber roofing
• Balconies and roof terraces
• Liquid-applied roofing
• All services in Amersham