I've found this neat carpet underlay/insulation stuff that, at about 1/8" , is claimed to have an R value equivalent to 1" of fibreglass insulation.. and it's a vapour barrier. It's made out of recycled cork and plastic and has a very nice pebbly tan finish. It's also cheaper than foam insulation per sq. ft., if their claims are true, and would make for some fantastic ceiling insulation. <br /> The problem with Reflectix insulation is that, in order to work correctly, there has to be something like a 1/2" air gap between it and any other surface (it's in the product literature). Layering doesn't work too well with it and, personally, I'm not too fond of the shiny-metal look. That's why I'm seriously looking at that cork underlay stuff. It looks pretty sharp and 3 layers, adding up to around R9, would only only be around 1/3" and preserve my headroom. Also, it's pretty tuff stuff and can be glued up, removing the need for framing. ..Willy.
http://www.homedepot.ca/product/nat...or-laminate-and-engineered-wood-floors/911488