General 
No Comments Green Roofs
Green roofs are becoming increasingly popular in the UK. On a green roof, the conventional covering, for example tiles or slate, is replaced with growing plants. As well as offering effective protection from the elements, green roofs look attractive and create valuable wildlife ecosystems. Organic matter is laid on manufactured layers or membranes, which are specially designed to protect against root invasion, allow for optimum drainage speed to minimise flooding and provide insulation. Plants can vary from low-growing evergreens like sedum to flowering plants, shrubs and even trees. The earliest green roofs covered prehistoric homes – and today, ancient wisdom combines with 21st century technology to make the modern equivalent an eco-friendly, cost-effective roofing alternative.
There are three main types of green roofs – extensive, semi-intensive and intensive. The type you choose will depend on how much time you wish to spend on maintenance and your available budget. As green roofing is heavier than conventional roofing, structural factors need to be taken into consideration. Some roofing companies specialise in this area. They can talk you through the pros and cons of each type for your situation and location.
The extensive green roof is the lightest in weight and requires the least maintenance, making it popular for sheds and garages. It is also the cheapest option. The soil layer should be shallow, around 20mm deep. Hardy, drought-resistant plants such as mosses, sedum and other low growing plants are suitable for extensive systems. One advantage of extensive green roofs is that they absorb water and allow it to drain away more slowly than conventional roofing. During heavy rainfall, this puts less stress on guttering and pipes when coping with excess water. However, make sure that you have installed adequate guttering and drainage pipes. Extensive green roofs can still become waterlogged quickly.
The semi-intensive type needs moderate maintenance. The soil layer must be over 150mm deep to support grass and perennial plants. By choosing colourful flowering plants, you are providing a much-needed food source for butterflies, bees and other insects. Perennial plants will need watering regularly during dry periods, so a suitable method of irrigation needs to be set up.
The intensive green roof is basically a garden. It is high maintenance, so easy access is a must. The soil layer is typically between 300mm to 450mm and can support bushes, flower borders and even a lawn. Obviously, the weight will be considerable and the extra loading requirements add to the cost, as does a suitable irrigation system. For ideas and inspiration, take a look at the famous intensive and extensive systems on the Canary Wharf estate in London.
Green roofs help you and the environment in various ways, absorbing CO2, providing effective insulation resulting in a reduced need for energy consumption and creating a haven for wildlife in built-up areas. Once established, they can last longer then conventional roofing and provide a colourful, ever-changing display. What more attractive and enjoyable way is there to reduce your carbon footprint?