Green and sedum roofs across Hampshire

Guide price

£4,850–£8,900

Survey

Free for new and replacement roofs

Quote

Fixed, in writing

Coverage

England, Wales, Scotland, NI

How much does a green roof cost in Hampshire?

Guide prices including VAT at South East rates. The fixed price comes after a free survey for new and replacement roofs.

Which flat roofs are common in Hampshire?

Flat roofs in Hampshire sit on lock-up garage blocks on estates, bungalows with flat-roofed side extensions and dormers and shops with flat-roofed rear stores below flats. 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. Approximate 1991–2020 regional averages based on Met Office data.

Building regulations in England

Replacing more than half of a roof over a heated room usually counts as renovating a thermal element, so it is insulated to current standards and notified to building control. Renovated roofs over heated rooms are insulated to around 0.16 W/m²K where that's feasible, and new extension roofs are built to 0.15 W/m²K. In Hampshire the application goes to Southampton City Council, Portsmouth City Council, Basingstoke and Deane Borough Council and 10 other councils. More on the rules.

Can a green roof go on my existing flat roof?

Only if the existing waterproofing is sound, root-resistant or protected by a root barrier, and has plenty of life left. In most cases it makes more sense to lay a green roof as part of a replacement.

Once the sedum, substrate and drainage layers are down, the membrane underneath is hard to inspect and expensive to repair, because the green layers have to be lifted to get to it. Putting a green roof on an ageing covering risks paying for the greenery twice. Our repair or replace guide helps you judge whether your current roof is a sensible base.

As for planning, re-covering a house roof normally needs no application if its appearance doesn't change materially. Because a green roof does change how a roof looks, check with your council, especially for listed buildings, conservation areas and roofs that are easily seen. The planning guide has more.

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.

Which towns in Hampshire do we cover?

• Southampton
• Portsmouth
• Basingstoke
• Gosport
• Waterlooville
• Farnborough
• Eastleigh
• Winchester
• Havant
• Andover
• Fareham
• Aldershot
• Fleet
• Totton
• New Milton
• Bordon
• Hythe
• Yateley
• Alton
• Emsworth
• Hedge End
• Romsey
• Hayling Island
• Tadley

Everything about green and sedum roofs → · All flat roofing in Hampshire →