Join the Green Roofs Revolution
Green Roof in London

Published on

March 5 2020

With densely packed urban spaces becoming more prevalent, the UK green roof industry has become an increasingly popular option to help tackle climate change, provide a rainwater buffer and encourage biodiversity. In this article Lantra Instructor and Verifier Chris Bridgman shares his insight into the ever-growing sector.

Bridgman Installing Green Roofs

In early 2019, the UK Green Roof Market Report identified that there are 1.5 million square metres of green roofs in London alone. What is a green roof I hear you say? A green roof is a living/vegetated/growing rooftop. Basically, on top of a waterproof roof surface (all roofs are meant to be to be waterproof) we can create gardens; anything we can do on the ground, we can pretty much do on a rooftop. One key requirement is that the building can take the weight of our proposed garden design.

Ten years ago, Bridgman & Bridgman were asked to do a green roof. Personally, I had never heard of a green roof; however, never wanting to turn away work, I agreed. I did some research and found out that European countries have been green roofing for years with sod roofs, turf roofs, sedum roofs and roof gardens.


In warmer climates, green roofs have evolved from putting a layer of sand on rooftops to stop the sun melting the bitumen or tar roof covering. Over time, the sand layer became vegetated as this additional layer created ideal growing conditions and airborne seed or seeds within bird droppings would germinate and cover the roof. The oldest green roofs documented go back to the Hanging Gardens of Babylon - well worth a Google.

Our European neighbours have been greening roofs for hundreds of years, but we are a little way behind. In my “fake it until we make it” story, we did our first green roof and it went well. I enjoyed the new challenge of construction, going from ground level to roof level and getting involved in something new to the UK. I felt that no one ever really appreciated the trees or plants, lawns or features we created or planted on the ground, but on the roof, wow, everyone wants to know what’s going on. Why are you doing that? A garden on the roof? Why? How? Will it take the weight? It catches people’s attention.


Why do we do it? What are the benefits of growing things on the roof? Well…. green roofs have multiple benefits. A green roof can insulate a building; protect the waterproof layer from the sun and rain; keep water on the roof and not overflowing sewers; recreate habitats that once stood before building occurred; and capture carbon omissions that pollute the air we breathe. Even more so, the greenery helps with health and wellbeing.

Our experience

We soon partnered with a green roof manufacturer Optigreen, part of the International company Optigrun - a German green roof product manufacturer. We undertook training and visited Germany to look at their millions of square metres of green roof (we didn’t visit them all!), but soon realised that if this ever took off in the UK, we would be kept busy for many years.

Since 2009, we have done lots of living roof installations; in fact, we now have an installation service, a maintenance service, a dedicated green roof vegetation nursery and deliver green roof training. We are so busy in the green roof department that we have reduced our landscape services on the ground.

Our portfolio has taken us across the nation: we have installed one of Europe’s largest turf roofs; at the time, Scotland’s largest wildflower roof; a convertible green roof (one that can be removed in sections or completely); and many roofs on new build houses and extensions, bus stops, bike sheds, bin stores and even a dog kennel. One of my favourite installations was a green roof in the Outer Hebrides along the Atlantic Ocean coastline.

The data

Recent figures revealed that the green roof market in the UK was growing at around 17.5% per annum. Over 40% of the UK’s green roof market is in London, with many boroughs and planning departments insisting on green roofs for new builds and extensions. The current Mayor of London fully supports green infrastructure, including it in the London Plan. It is likely that the new Metro Mayors will adopt the London Plan and then try to improve on it, meaning another potential spike in the market. Having said that, it seems more people are now choosing to have green roofs from a design perspective, rather than a planning requirement perspective.

Green roofs don’t just need to be flat. They can be on pitched roofs or domed roofs and can also be incorporated with solar panels. Green roofs are also beneficial in rural areas, where instead of the water draining off within 15 minutes (traditional roof), a green roof will slow this process down by up to 24 hours. Most of the water will either be used by the vegetation or evaporate, meaning the water is kept at source.


This is all fantastic but who are installing these roofs? Landscapers? Roofers? Gardeners? Anyone? Some traditional roofers have embraced the challenge and install green roofs successfully; others find the installation easy but are unable to offer ongoing maintenance and horticultural support to the end user. Some landscapers/gardeners have also joined the industry but did not adequately mitigate the risk of puncturing the waterproof layer. This means that whoever is installing a green roof needs to understand the principles of both roofing and horticulture, but also appreciate that overloading the roof with materials could collapse the building.


Bridgman Green Roof

To drive up quality and standards, Bridgman & Bridgman, Bauder, Langley Waterproofing, ICB Projects,, BALI, worked together with leading awarding body Lantra to develop a certification that recognises the required level of learning and skills for the rapidly growing green roof market in the UK. Installers currently possessing Construction Related Occupation skills cards, available to people working in construction-related occupations not covered by other CSCS (Construction Skills Certification Scheme) cards, now require a skills card that reflects their specific trade when their current cards expire. With the launch of a new suite of Green Roofs training and assessment courses, it will now be possible to gain a Lantra Skills Card and Blue Skilled Worker LISS/CSCS card as a Green Roofs Installer. LISS refers the Land-based Industry Skills Scheme.

The green roofing industry urgently requires a certified, skilled workforce to cope with demand, and to raise standards within the profession through compliance with new requirements of occupational competency from the Construction Industry Training Board (CITB) and CSCS. The training is also open to anybody looking to gain news skills or add green roofing to their portfolio, including architects, specifiers, gardeners, roofers or new entrants to green roofing.

Article by Chris Bridgman, Partner at Bridgman & Bridgman, Lantra Instructor and Verifier.

Find out more about our Installing and Maintaining Green Roofs courses