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It appears that Washington DC has a green roof rebate program where I can get $15/sq.ft to install a green roof.

Green roofs are stormwater management practices that capture and store rainfall in an engineered growing media that is designed to support plant growth. A portion of the captured rainfall evaporates or is taken up by plants, which helps reduce runoff volumes, peak runoff rates, and pollutant loads on development sites. Green roofs typically contain a layered system of roofing that is designed to support plant growth and retain water for plant uptake while preventing ponding on the roof surface. The roofs are designed so that water drains vertically through the media and then horizontally along a waterproofing layer towards the outlet. Extensive green roofs are designed to have minimal maintenance requirements.

I like the idea of being environmentally friendly and storm water run off is a major issue. I am a little worried about minimal maintenance as I don't have access to my flat roof and do not like the idea of climbing a 35 foot ladder with gardening supplies.

What type of maintenance is typical of a well designed green roof?

Bamboo
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StrongBad
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1 Answers1

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Where I live there are long hot summers and winters with alternating melt and freeze cycles. The green roofs that work are the ones that receive regular weeding and replanting. Surprisingly you might have to water your roof during a prolonged hot dry spell. If plants die out weeds will move in.

Here are two roofs

Roof of the War Museum, Ottawa : still looks good after many years War Museum Ottawa

Algonquin College: as built Algonquin College

and as it looks now after a hot summer with, apparently, no maintenance Algonquin College aerial view

Here is a visual of a typical installation. A lot of preparation required green roof schematic

You asked:

What type of maintenance is typical of a well designed green roof?

  • monthly weeding
  • annual planting in the spring to fill in dead spots or rejuvenate the medium
  • watering during droughts

What is needed is easy access to do this. Slanted roofs are a problem to get to but good to drain water off.

kevinskio
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