green roofs

[spdykyla]

Does anyone know if green or living roofs are practical in Puna area, specifically Eden Roc? I like the way they look, not that I will need the extra growing space [] Thanks!!!

[Rob Tucker]

Practical? That may be in the eye of the beholder.

Fact is that they are extremely heavy and need to be designed structurally as though they are concrete+ in weight. They also require expensive water proofing and drainage. Extremely difficult to find or repair leaks when they occur and with rooting plantings they will occur. I would suggest that the costs, properly done, might be 10x plus a conventional roof.

[Carey]

Another big problem with the plantings on the roof is that many roofs here are for catchment for the water supplies of the property... green roofs would not be as practical for catchment, as you would have to have better particle filtration systems....and earth filtration for the rainwater is not really a big need here.... most of the purification/filtration is for things picked up on the roof & within the catchment system...

[Seeb]

Seismic design also, all that weight up high

unless your planning on building a bunker it would not make any sense

[kiarajeckson]

Green roofing is not the viable option for the city as the environment conditions are not suitable for green roofing.One more thing is that the green roofing require high level of roof maintenance cost so it will not be a proper solution to design the roofs of our houses.

[MarkP]

Got this from Wikipedia:

"Green roofs serve several purposes for a building, such as absorbing rainwater, providing insulation, creating a habitat for wildlife, and helping to lower urban air temperatures and mitigate the heat island effect."

I have property in Eden Roc. We get a phenomenal amount of rain and have no county water. Rainwater catchment is a necessity and everything I have ever read about good rainwater catchment protocol is the opposite of what you would get with a green roof. For example you don't want to create a habitat for wildlife on the roof that your drinking water comes from. The water that makes it off your roof soaks into the ground due to the excellent drainage we have so in that respect we are not at all like the 90% asphalt cities where green roofs might make a difference. I have never been too hot in Eden Roc so that is another benefit we can't take advantage of. I have been too cold at night but soil, particularly wet soil like we would have probably 95% of the time, is a poor insulator. It provides mostly thermal mass. Thermal mass helps where there are large day/night temperature swings. We don't have that. As for mitigating the heat island effect I think it more practical to put the effort into appropriate plantings such as shade trees. Finally, we are in earthquake country. While researching methods of building a house out of all the stone we have lying around in Eden Roc I came across countless pictures of collapsed stone houses and constant references to how one of the major problems was the mass of dirt that poor people in treeless landscapes piled on their roofs in place of real (and expensive) insulation.