Nimrod Environmental limited
Green Roofs
What is a Green Roof?
A green roof is a roof that is partially or completely covered with vegetation and a growing medium, planted over a waterproofing membrane. It may also include additional layers such as a root barrier, drainage and irrigation systems.
Nimrod encourages clients to consider the installation of a green roof on any flat roof space on their buildings; home or office as they have many environmental benefits.
Also known as “living roofs”, green roofs serve several purposes for a building, such as absorbing rainwater and reducing flooding, providing insulation, creating a habitat for wildlife and helping to lower urban air temperatures.
There are two main types of green roofs:
Extensive Roofs
The extensive green roof, also referred to as an eco-roof, has fewer and thinner layers making it much lighter. Since they have less soil medium, the plant selection for extensive roofs is usually mosses, succulents and grasses—all low growing plants. These plants grow from 16 to 24 inches tall, creating a low profile roof. The extensive green roof is very low maintenance since most of the plants are drought tolerant and excellent for increasing bio-diversity
Intensive Roofs
The intensive green roof is thick in construction and can support a wide variety of plants, including taller plants, due to a deep soil medium. Though intensive green roofs require additional maintenance and materials, they also provide the opportunity for an outdoor area that can be used recreationally or to grow food.
Brown Roofs
Brown roofs are similar to green roofs in that they share many of the same benefits and construction methods. However, when a brown roof is designed the overriding aim is to encourage bio-diversity.
Specific biodiversity aims can include:
- Maximising the number of species living on the rooftop
- Providing a habitat for a specific species (e.g. a threatened species living on the site that a building is being constructed on)
A basic example of a brown roof could utilise recycled material and spoil (see picture below) from the construction site to attract wildlife that may have lost it’s habitat during the build period. Local wildlife could then be left to colonise the roof over a period of time with minimal human intervention.
Brown roof systems should use a high percentage of recycled products. Guides suggest that the implementation of a brown roof can be up to 100% recycled materials. This would incorporate a stringent selection of products; but this target is possible to reach. Suppliers and manufacturers should also be able to provide product certification to substantiate this. A brown roof should however incorporate a very minimum 40% recycled products.
What are the Environmental Benefits of a Green Roof?
- Absorbs rainwater and reduces storm water run off, reducing the risk of flooding.
- Creates natural habitats and attracts wildlife.
- Extends the life of the roof by protecting it from the elements.
- Reduces heating costs by adding thermal resistance value. Reduces cooling on a building by fifty to ninety percent. An independent study showed that green roofs can potentially reduce heat loss and energy consumption in winter conditions.
- Helps to insulate a building for sound; the soil helps to block lower frequencies and the plants block higher frequencies.
- Filters pollutants and carbon dioxide out of the air which helps lower disease rates such as asthma.
- Filters pollutants and heavy metals out of rainwater.
- Can be used as potential agricultural space.
- Can be used as amenity space – in dense urban environments there is often a lack of green space for residents. Roof Gardens and roof top parks provide important green spaces to improve the quality of life for urban residents.
- A concentration of green roofs in an urban area can even reduce the city's average temperatures during the summer.
Green Roof Maintenance
Nimrod fully understand the benefits of all the different types of Green Roofs and are proud to provide a maintenance service that enables these roofing systems to perform to their best without negating their levels of biodiversity.
All products used by Nimrod are industry recommended and are supplied to provide the best maintenance programme available, this along with the removal of the more aggressive (dominant) species of plants that can self seed, provide the green roofs the time and space they require to fully mature.
Typical maintenance we will carry out:
- Removal of unwanted plant material and debris.
- Correction of any localised plant system problems.
- Replacement of any failed plants (as required).
- Application of nutrients.
- Removal of dead foliage (if required).
- Checks on outlets and drainage.
- Replenishment of any areas of settled substrate (growing medium).
- Pruning, mowing & removal of dead vegetation.
- Apply additional irrigation in accordance with each plants requirements.
(2), (3) and (7) are generally confined to the first year of installation. Maintenance requirements may reduce as the plant system establishes. We would recommend that a continuous maintenance schedule to be introduced to maintain a healthy plant regime.
Green Roof Warranties (Insurance Backed)
For further information on the warranties that we offer for Green Roofs please click here
