We are looking into building a deck made of composite material since we want this to be the last deck we build. We live in Ottawa, Ont, Canada. We want to know if there are stores other than the usual Home Depot or Lowes that sell such material? Are there particular aspects of building such decks that we should consider prior to building. Any help provided would be greatly appreciated. This would be a two-tier deck: upper - 6'x12' and lower - 16'x6'5in. (approx.) with a set of two steps on two sides of the lower deck. Can any provide an approximate cost of material only. Thanks again.