Green Roofs

Defining green roofsWhy use green roofs? Types of green roofsConstruction methodsExamples of green roofs

Defining Green Roofs

Different definitions but simplest of them being: A roof of a structure that is covered with vegetation of some nature that can range from trees to moss

Why use a green roof system Provide high degree of insulation so keep

heat in and cold out. Therefore reduce heating costs. Example U.K use more energy keeping buildings cool in summer than warm in winter

They retain between 60%-100% of rainfall. So reduces pressure on drainage systems reduce need for attenuation tanks

Absorbs Co2 emissions.

Why use a green roof system: continued

Reduce the effect now referred to as “urban heat island” as cities as generally warmer than country side.

Other benefits include improved: Life span double that of traditional

roofs quality of water Air quality amenities

3 main types of Green roofs: first one is: Intensive green roofs:

no limit to amount of plants or trees requires regular maintenance and access.

Due to depth of substrate. Most expensive. Likely to be found at ground level or flat

roofs like apartment blocks and appear like a park with paths, benches and even playgrounds

One building contains 35,000 plants and 75 types

Intensive green roof:ACROS Fukuoka building in Fukuoka city Japan.

Semi-intensive green roofs This type is restricted to smaller

shrubs and grasses. Substrate layer is not deep enough

for trees. Access is required for this type but

not as much as this is not designed for people. Maintenance is less than the previous example.

It is also less expensive.

Semi-intensive green roof: Roof cover on Airport in Amsterdam

Extensive green roofs Substrate is very minimal about 15mm There is a limit on the types and amount of

grass of plants used This type is the lightest, the cheapest, very

little in maintenance. What is involved in maintenance? Using the

Lawnmower to cut the grass??? These characteristics make it the most

applicable to domestic dwellings. So I shall discuss this type in further detail

Extensive green roof: domestic dwelling

Methods of constructing an extensive pitched green roof

Roof loads must be calculated ensuring roof is strong enough when soil is dry and saturated

Begin with ply decking and timber up stands.

Apply bitumen based roof felt and seal with waterproof mastic.

Methods of constructing an extensive pitched green roof

Turf hooks are then screwed onto the roof structure

Followed by front edging boards to retain the soil.

The membrane is then laid down this is what provides the basis to which the soil grips onto and grows around.

This also sealed at all joints.

Membrane being rolled out.

Methods of constructing an extensive pitched green roof: continued

The soil matter can then be displaced over the roof.

It will then be spread evenly over the roof surface.

Finally the grass, plants or turf can be used over the soil.

The green roof is then finished.

Houses that may be familiar with green roofs

Gary Neville's proposed new house development.

The teletubbies house.

Gary Neville’s proposed new house

Teletubbies House