Green and sedum roofs in Durham

Why choose a green roof in Durham?

Small commercial buildings and blocks in Durham with a flat roof sometimes add an extensive green roof as part of a refurbishment. The structural check and safe access for maintenance matter even more on these larger roofs, which may need edge protection or fall-arrest points for each visit.

In a town like Durham, flat roofs are commonly found on 1960s and 1970s link-detached houses with flat-roofed garages and porches or terraced streets with flat-roofed rear kitchens and bathrooms. England averages roughly 870 mm of rain a year; the North East is drier than the west but cold and windy near the coast, so wind uplift and freeze-thaw are in the specification.

How much does a green roof cost in Durham?

For Durham we use North East rates: £4,100–£7,500 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.

How is a green roof built on top of a flat roof?

From the bottom up, a green roof is a deck, a waterproofing system with root protection, then drainage, filter, growing medium and plants. The waterproofing does the job of keeping water out. The green layers sit above it.

• Warm roof build-up: vapour control layer, insulation and waterproof membrane on the deck, then the green layers on top. This is the usual choice on a home extension being re-roofed.
• Inverted build-up: waterproofing on the deck, then insulation boards designed to sit above it, then the green layers. This is common on terraces and some commercial roofs.
• Root barrier: roots will exploit any weakness, so the membrane needs to be root-resistant. Some membranes are tested as root-resistant; others need a separate root barrier laid on top.
• Drainage and edges: a drainage layer carries surplus water to outlets, and a gravel or pebble strip is usually left around edges, outlets, upstands and rooflights to keep them clear and accessible.

Upstands still need to rise around 150 mm above the finished surface, which on a green roof means above the top of the growing medium. We check that at the survey, alongside the external fire performance of the build-up where the roof is close to a boundary.

What's included?

• Structural check of joists, deck and supports
• Warm or inverted build-up to suit the roof
• Root-resistant membrane or separate root barrier
• 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?

• Spennymoor · 5 mi
• Chester-le-Street · 6 mi
• Houghton-Le-Spring · 6 mi
• Stanley · 8 mi
• Washington · 9 mi
• Bishop Auckland · 9 mi

Other flat roof work in Durham

• EPDM rubber roofing
• Flat roof repairs
• Single-ply membrane roofing
• Flats, HMOs and block roofs
• Torch-on felt roofing
• GRP fibreglass roofing
• All services in Durham