I have a two level deck which my contractor promised would be water proof. The upper deck is constructed of 4x8 pressure treated ply, all the seams were caulked, a layer of ice and water shield was applied over top and the deck boards screwed down. Needless to say the decking is not waterproof and I am not able to enjoy the lower deck during wet weather. If anyone knows how I might be able to correct I would like to hear from you. If possible detailed information would be extremely helpful when I discuss corrections with my contractor.Thank you.

The decking was screwed into the shield?

The deck boards were screwed through the shield. I understand that this is the reason it now leaks. What can you suggest as a remedial action?

No, you'll have to remove the decking and lay down another moisture barrier but this time use what is called "duck boards" it is basically a floating deck.
I found a good example w/ pics for you at this BC site: http://members.shaw.ca/provip/products.htm With your weather in Ont. it would even be more important with the freeze thaw.

Another option is to use the under deck systems, even to go to a vinyl decking now you would have to remove the shield... which isn't so easy.

Alter Eagle Construction & Design

Thank you! I will spend some time and review the information on that site. Someone else suggested "torch down". Are you aware of the details of this technique?

Yes, that would also require you to remove the ice & water shield you have down now. That is the way I would have done it, then the floating deck (duck boards) above that. You do have to understand I haven't seen the project though, there may be some reason for your contrator to use the ice & water shield in that location too?

Hot mop is another choice.