For both of these we need to follow specific green roof construction and maintenance procedures.
Extensive green roof construction.
For a conventional roof.
Typically these roofs will have more soil and some small shrubs as well as the low growing wildflowers and sedums found on an extensive roof.
Your roof deck be it concrete or screed will need to be waterproofed.
Green roof irrigation system.
Intensive roof construction is largely the same but may involve additional elements.
Moisture retained by saturated media after free draining 40 60 typ.
A semi intensive green roof can give rise to a richer ecology with more diverse plant and animal species.
A properly designed and installed extensive green roof system can cost 108 248 m 2 10 23 sq ft while an intensive green roof costs 355 2 368 m 2 33 220 sq ft however since most of the materials used to build the green roof can be salvaged it is estimated that the cost of replacing a green roof is generally one third of the initial installation costs.
Green roofs can help reduce energy costs for a building by acting as another layer of insulation between the inside and outside of the roof.
Green roof components growing media water holding capacity field capacity maximum water capacity astm test.
Extensive green roof an extensive green roof system is characterized of its vegetation ranging from sedums to small grasses herbs and flowering herbaceous plants which need little maintenance and no permanent irrigation system the growing medium depth for an extensive green roof system is typically 6 inches or less.
They are differentiated on the basis of plant selection growing medium type and overall cost.
However semi intensive and intensive roofs do.
Moisture retained by media that cannot be removed aka wilt point 12 18 typ.
This is most noticeable in intensive green roofs since there is a thicker and more consistent layer of soil which provides a higher insulating value.
A general characterization of the two types of green roofing systems follows.
15 to 50 per square foot.
The government undertook fire tests for green roofs and walls and concluded that the current guidance provided by the green roof code was adequate and extensive green roofs installed following the code would not be deemed a fire risk.
For an extensive green roof the plants should be able to grow in under 5 inches of soil.
Some roofs will already have a waterproof layer.
Therefore it is unlikely that a green roof will lead to issues with insurance.
Extensive green roofs which are most often used for residential homes do not require watering.
Step one primary waterproofing layer.
Plants for an intensive green roof may be able to have a deeper root system.
A 2006 study by the university of michigan comparing costs of conventional and green roofs showed that on average installing a green roof costs about 22 00 sq.
These systems are ideal for efficient stormwater.
Generally there are two types of green roof systems.
Extensive green roofs.