Green Roofs Australia (GRA) has been very fortunate to receive this photo documentation from a roofing contractor who is hoping green roofs will put more traditional roofs out of business.
Washington roofing contractor Troy Wagner replaced his own roof with greenery after he observed that green roofs last much longer than “clean roofs”.
He sent GRA a written account of his step-by-step green roof progress, in which he writes:
“Over 15 years I figure I have looked at 15,000 roofs, and occasionally I would come across a roof covered in moss. In the western side of the state of Washington we are blessed with 50 inches of rain a year, this means moss on all the roofs. Insurance companies require the roofs to be moss-free, believing it leads to leaks, so to find a roof covered completely with moss is rare.”
But during his professional life inspecting roofs, Troy observed that moss-covered roofs lasted much longer than ‘clean’ roofs — sometimes more than twice as long:
“When inspecting the roof system that should only last 20 years and finding those covered with moss lasted 40 to 50 years, and only were changed out because the home was being sold or an insurance company saw it, I scratched my head. After seeing this a few times I started to believe that the moss was protecting the roof from the sun’s radiation. The sun’s radiation can cause a roofing system to loose the ability to expand and contract with the change in temperature causing it to crack, curl and become brittle.”
This was when Troy started investigating vegetative options:
“Five years ago I ran into a house with a low pitch 3/12 that had wood shingles, no felt paper and on skip sheeting (1×4s with a 4” space) the roof was 75 years old, covered with grass that had grown in the moss. This caused a light bulb to go off in my head and I said ahhhh, then ran home and tore off my roof.”
The results are pictured above and below, and Troy has given GRA written step-by-step documentation on how he built his own spectacular green roof, which includes an impressive vegetable patch (below). (Australian residents please note: US load bearing specifications differ.)
Troy is enthused about green roofs’ potential to improve our environmental footprint.
“If everybody did this I would be out of business as a roofing contracter, and I am ok about that… I offer free advice to anyone wanting to do this.”
What happens in the winter to this roof garden? Freeze/ thaw/ soil runoff?
I love the idea but what OHS considerations are there? Roofer and tilers can’t be on a roof without harnessing. Surely vegetable gardening on a pitched roof would require similar safety actions. How do you ensure homeowners would be that responsible?