Green roofs

A key factor in the future will be the development of green spaces within cities. While it will be impossible to provide every home with a garden, there are other very practical possibilities.

One is the development of green roofs which contain plants that will attract wildlife, as well as incorporting a wide range of green benefits for the overall environment.

The UK has been slow on the uptake of green roofs — since the Millennium, more than 30m sqm of green roofs have been created in Germany alone.

Now an Oxfordshire couple have decided to pool their talents and set up their own company, bringing the methods involved to the UK.

Kay Davies, 39, and her 45-year-old husband Gareth, who live in Drayton, near Abingdon, work as a garden designer and building surveyor respectively.

Mrs Davies said: “We struggled to obtain quotes for this kind of work, so we decided to find a way of setting up a company ourselves.

“It is an area we are passionate about. Gareth is fascinated by green ways of building and I always try and integrate wildlife spaces into my garden designs.”

A massive boost for the couple came when their firm, Oxford Green Roofs, was accepted to exhibit at the recent Grand Designs Live show in London — all the more remarkable because it came just as the business was being set up.

They teamed up with Benson building company Eco2h2ouse putting a wild meadow grass roof on top of the building to further boost its green credentials.

Mrs Davies said: “It was an amazing opportunity — the house was right at the centre of the show.”

Understandably, a lot of research has gone into setting up Oxford Green Roofs. Mrs Davies is particularly keen on using native plant species that are specific to the particular area where the building will be constructed.

In turn, that will encourage wildlife.

Where native species are not possible, Mrs Davies will use sedum, a cactus-like plant that is designed to be hardy and needs little or no watering. There are two different types of roofs that can be installed — intensive and extensive.

An intensive green roof requires a deep growing medium to enable the planting of trees and shrubs. It requires calculated load bearings and an irrigation system, but has all the benefits of a garden.

The extensive green roof can provide a green, aesthetically-pleasing and wildlife-friendly space without labour-intensive maintenance.

Green roofs are also ideal for people with very small or no gardens at all, as they offer residents a green space.

“If they have a flat roof or a shed, then they can have a green space and do their bit for the environment,” said Mrs Davies.

At the moment, the Davies’ are aiming more at the domestic market, as that is where they feel their expertise lies.

“We want to make things happen for ordinary people who want to know what they can do to make their home more wildlife-friendly.”

Mrs Davies admits that in winter the green roof will not look as appealing, but argues that it is part of a natural process, allowing regeneration in the spring. And the more mature the planting, the better it will look year-round.

“It is possible to have flowers from January to September,” she said.

“The beauty of it is that maintenance is very low. It may need a little water and you can either mow it, or leave it to have a wild look. This is where the design comes in.”

Building the roof involves adding an impermeable fibreglass membrane to ensure there are no leaks and then adding the substrate, which does not have to involve a rich, fertile soil.

The Green Roofs approach is to use rubble and even pieces of reclaimed brick which cannot be otherwise recycled.

Mrs Davies said: “The theory dates back to World War II when it was discovered that a lot of bombsites had become homes for wild plants. When they were regenerated, the plants disappeared.”

She added: “The design will be based on what the client wants — every project will be different. We are not expecting every one to be a Grand Design — we will work with whatever space is available to create an area for wildlife.”

Mrs Davies said that, as well as the roof, any grass area can be planted in a similar way to encourage birds and insects still further.

She sees green roof construction as being a valuable educational resource for youngsters in primary schools.

Then, of course, there is the beneficial effect on the environment. As well as looking the part and encouraging wildlife and insects, green roofs naturally absorb carbon dioxide and give out oxygen, improving air quality.

In addition there is the benefit of good insulation, trapping heat in the winter and keeping the building cool in the summer. They even provide good sound insulation.

And green roofs also store water, rather than allowing it to run off directly into the drainage system, and allow it to evaporate back into the atmosphere.

In times of heavy rainfall, they help alleviate the problem of surface run-off which can lead to flooding, a particular problem in cities such as Oxford.

Years ago, what may have seemed a bit of a wild idea, is set to become a reality of urban design in the near future.

o Contact: Oxford Green Roofs, 01235 204187 web: www.oxfordgreenroofs.co.uk