A Thatch Roof is a Green Roof

I was reading a report on green roof potential in Los Angeles, and it dawned on me that thatch roofs are green roofs. During dry months the are just twigs, but when it gets moist, they may turn into a planting medium.

A web search turned up this site for a company in Japan that thatches roofs. The challenge in Japan is that building codes don't seem to allow thatch, except on historical buildings. So the thatcher business is in decline.

In England, it's a different story. The demand for thatch roofs is higher than in the past 70 years. Unlike the tar shingles and tarring that we're used to, thatch is carbon-neutral. It also lasts 60 years (whatever that means - there are thatched roofs that are older than the United States).

Even the local traditional Tongva buildings were hoop-frames with thatch material covering the walls and roof. I wonder if they used grasses or reeds from the San Gabriel river.