Green Roofs

Service Details

Green roofing has moved from a niche specification to a mainstream requirement in London. Many boroughs now include green roof policies in their local plans, and planning committees increasingly expect to see living roofs on new developments. Capital Roofing has been installing green roofs for over 15 years, and we combine our deep waterproofing expertise with specialist horticultural knowledge to deliver systems that thrive.

A green roof is, at its simplest, a waterproof roof with a growing medium and planting on top. In practice, the system is more complex than that. A typical green roof build-up includes the structural deck, a vapour control layer, insulation, a waterproof membrane (which must be root-resistant), a drainage layer, a filter fleece, growing substrate, and the planting itself. Each layer must be correctly specified and installed for the whole system to perform.

We install both extensive and intensive green roof systems. Extensive green roofs use a shallow substrate depth (typically 80mm to 150mm) planted with sedums and drought-tolerant species. They are lightweight, low maintenance, and suitable for most flat roofs with adequate structural capacity. Intensive green roofs use deeper substrates and can support shrubs, perennials, and even small trees, creating genuine rooftop gardens. Intensive systems are heavier and require more structural support and ongoing maintenance.

The waterproofing layer beneath a green roof is the most critical component, because any failure is extremely difficult and expensive to locate and repair once the growing layers are in place. We use proven waterproofing systems from manufacturers who specifically warrant their products for green roof applications, and we carry out rigorous flood testing before the growing layers are installed. Our decades of waterproofing experience give us a significant advantage over green roof specialists who lack a roofing background.

The benefits of green roofs are well documented. They reduce surface water runoff by absorbing and slowing rainfall, which helps manage London ageing drainage infrastructure. They improve thermal performance, reducing both heating and cooling costs. They provide habitat for birds, insects, and other urban wildlife. And they can significantly improve the appearance of a building, particularly in dense urban areas where any green space is valuable.

We have installed green roofs on schools, residential developments, commercial offices, and community buildings across London. Each project is designed in consultation with the client, the architect, and our horticultural partners to create a system that meets the specific site conditions and planning requirements.

For green roof consultations and quotations, contact our Blackheath office.