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Green Roofing


Why choose Green Roofing?

Traditional roofing is designed to remove water as fast as possible from the roof surface. Conversely, green roofing actually retains water on the roof. Green roofing costs twice as much to install and can make repair work difficult. So why on earth would you consider putting a green roof on your building?
  What is Green Roofing?A Green Roof is a living environment on top of a building. Modern ecological roofing technology has been developed primarily in Europe. Up to ten per cent of the roofing in Germany is now green. Green roofing is built up in layers. Each segment provides a different function.The bottom layer sits on top of the roof structure and provides a waterproof seal to the building. This may come in the form of metal sheets or a synthetic membrane. A drainage layer is added to allow water to leave the roof. This is followed by a filter and root protection layer. The root protection membrane prevents plants from penetrating the waterproof membrane and causing leaks into the building.The final layer is the soil or growing medium in which the plant growth sits. Green or “living roofs” can be divided into three main categories. Extensive, Intensive and Biodiverse.

Extensive green roofing

Extensive green roofing, (also called Eco roofing) is used to grow herbs, mosses and grasses. The growing medium is relatively shallow with a depth of between 60-200mm. The weight of the roofing is 60-150kg per square metre. Eco roofing is used where there is little or no human foot traffic and low maintenance roofing is required. This type of roofing is the cheapest to install.

 Intensive green roofing

Park gardens and roof gardens are constructed using Intensive green roofing. This category of roofing gives the widest range of planting situations. Flowers, shrubs and even trees can be planted. The depth of the growing medium is between 150-400mm. This raises the weight per square metre up to 180-500kg and requires a significant structure to support it.


Bio diverse green roofing

Bio diverse roofing is designed to be left alone to reproduce a natural ecosystem. Soil levels on the surface are varied to create a wide range of different habitats for different species. Local plants are grown and wind swept seeds are allowed to take root.  Bio diverse roofing is often aimed at providing a particular habitat for a threatened species.


Green Roofing Will Save You Money

Green roofing can turn an ugly urban roof into an aesthetically pleasing feature. As well as the aesthetic value added, green roofing provides many financial benefits. The waterproof membrane on roofs is subjected to high UV levels. These Ultra Violet rays destroy the surface of the roofing causing leaks and the need for early replacement. The growing medium of living roofs provides a protective layer preventing damage from the sun. It acts as a sunscreen. This can double the life span of the roofing and recoup the initial extra cost of installation. Moreover, green roofing provides a thermal layer keeping the building cooler in summer and warmer in winter. This will save you money on heating and air conditioning. Town planners within local government have now realized the benefits of green roofing. Many district councils offer financial incentives to building developers using green roofing on new buildings. This trend will continue as the need to reduce carbon emissions increases.


Green Roofing will help the environment

City roofs built with traditional roofing materials absorb the suns rays and emit them as heat. This has lead to the urban heat island effect. This effect is most noticeable at night with town areas being warmer than surrounding areas. The air temperature in London is about 6 degrees higher at night due to the urban heat island effect. Ecological roofing does not absorb the heat radiation so the effect is mitigated. Thus, the need for air conditioning may be reduced in hotter climates.

Mass urbanization leads to high water run off and flooding. Huge areas of concrete and tarmac prevent the natural drainage of heavy rainfall. Green roofing absorbs between 50-75% of rainfall, gradually releasing it back into the environment. This evaporation process also cools the building reducing energy consumption and carbon emissions even further.

Depending on the growing medium and the plants present, green roofing can store up to 239 grams of carbon per square metre. It provides a valuable habitat for plants and insects as well as providing food for bee’s and seed eating birds. In effect ecological roofing replaces the green footprint removed by the building.  


Modern roofing materials provide a lighter, easier to maintain option for eco roofing. Lightweight mats and module trays allow repairs to be carried out without the need to take the whole roof apart. The trays are easy to maintain and protect the roof surface from harmful Ultra Violet rays. The long term financial savings, coupled with the benefits to the environment make green roofing worthy of serious consideration. For information about our Wellington Roofing Contractors please click here.  simon cowham