Decks, Patios, Porches and Docks - 2nd Floor Deck

I was interested in building a large waterproof 2nd floor deck over top of a lower deck of the same dimensions and was wondering how I would do this. I thought of slightly sloping the joist system under the upper deck (1/4 inch per foot) away from the building and covering it with waterproof plywood, but wasn't sure what to put over this to waterproof it and how to incorporate a cedar deck on top of this (do you use sleepers and a floating system on top?)

What do you recommend as a waterproofing layer?
How do I build my decking on top of this?

The structure is in Ontario, Canada and is subject to harsh winters and hot summers...

Thanks

Use Underdeck below the upper deck. It's a system of "F" channels and plastic panels that attach to the deck joists, then dump the water into a gutter. Check it out at underdeck.com

Can Underdeck be used to seal a deck above a room, such as a deck that is above a room on the first floor of a house?

A4B4,

Welcome to DoItYourself.com and the deck forum.

I suppose it could, but I wouldn't, unless there was a waterproof surface above the room and below the Underdeck. The "F" channels of Underdeck are caulked to the sides of the joists, but there is always a chance of a leak someplace in the system. What Uderdeck would do for you in a case like this would be to prolong the life of your waterproof surface.

Thank you lefty. I actually worked out a system where similar to Underdeck, except I'm using plywood with EPDM. I had to do this to conserve vertical space. It won't look as pretty, then again, being inside a ceiling, no one will see it anyways. Thanks for the response though!