R Value Of Intensive Green Roof

For a conventional roof.

R value of intensive green roof.

With that in mind the real variable in the weight is the depth of planting material. The soil mixture is at least 8 inches deep and can be as deep as 15 feet depending on the architectural and plant features the homeowner wants. Once you have more than r 20 in a roof assembly that is you meet the code things pretty much don t matter. An intensive green roof weight varies from 35 to beyond 100 pounds per square foot when dry.

An intensive green roof is more high profile and resembles a roof garden because it has a much wider variety of plants. 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. 8 to 20 per square foot. 15 to 50 per square foot.

Perhaps the most important benefit of green roofs is that they can reduce the amount of and improve the quality of stormwater runoff from a building site. The soils of a green roof will capture a significant amount of stormwater which is absorbed and used by the planted material. Green roofs save energy compared to uninsulated roofs or poorly insulated roofs or even better black poorly insulated roofs. In other words go above r 20 and make green roof decisions for other reasons than energy.

Over its estimated lifespan of 40 years a green roof would save about 200 000 of which nearly two thirds would come from reduced energy costs.