Cob: RE: Sealing cement roofs

[Patrick Newberry]

I know this isn't very natural, but I heard about some cement roofs being sealed in Guatamala using old styrofoam and gasoline. Mixed to gether I guess it melts the styrofoam into some type of a substance that can then be painted on to the cement and seal it. 

This is currently being used on habitat homes in Guatamala. 

Has anyone else heard of this. I'll be putting a ferro cement roof over the outer section of my cob house and have been looking into fibers (looking at steel and fiberglass) to try to keep it as thin as possible since I am building by hand and must carry the cement up to the roof. 

Pat
www.gypsyfarm.com