We are planning to build a second floor deck over an existing deck. Will be 16 x 12 when finished. My question is this. We don't want the upper deck to allow water to drip onto the lower deck when raining. How can this be prevented? I want to use 5/4 decking on top, but don't see how we can do that and still be "drip-proof".

They Do Make A Product Just For This, Its Called Underdecking, There Are Also Some Other Companys That Make The Similar Products. The Way It Works It Panels Are Placed In Between Your Joist The Collect The Rain And Then Are Diverted To Channels That Run To The Edge Of Your Deck. The Rain Then Will Either Run Off The Edge Or You Can Install A Gutter And Down Spout, For Your Size Deck You Should Expect To Pay. 950 To 1100 For The Whole System,
You Don't Need A Lot Of Tool To Install This, Your Job Would Take Around 5hr To Complete, Granted I Do This More Often But Its Not All That Hard.
Ill Send You A Link To Help You Find The Site,

Well I Can't Get The Link On Here, Just Type In Under Deck And Go To There Site

Thanks! I'll give it a shot.

Here's the link:

Underdeck, Under Deck, Dry Under Deck, Under Deck Ceilings, Under Deck Cover

Thanks for the link. It was very helpful.