Your roof top deck has plenty of clearance,most of mine have the width of the stringers 1 1/2''. I would sugest using counstruction adhesive as well as SS screws be very sure the screws do not go thru the stringers be very sure as well during install you dont damage the roof...like hiting it with the edge of a board,droping a drill bit first on it,steping on a screw things like that. Your right if your going to use anything on it use the S American lumber not manmade material. With your pool deck provide cross ventalation. This can be done with screen vents in the framing if this is not completly possible install floor vents in the decking combined with the frame vents. Cross ventalation is a vastley over looked but much needed addtion to any decking project. The gap between the decking boards will have no effect one way or the other venting your project unless there is air moving under it. If possble a drain system under the pool deck might help if done corectley but do not put a ground cover like plastic sheet/tar paper under it 1'' ipe will react the same way 3/4'' ipe will under the same conditions. The life span of both is also the same. J.

I ran into this issue many years ago, there was no solution so I invented one and got a patent on it (see: http://www.freepatentsonline.com/5195281.html). There are no pictures provided, but basically what I did was to insert longintudinally V-folded aluminum flashing to hang on and fit in between the joists. I then put 2x4 "runner boards" atop the joists with minimal screw penetrations (and a rubber washers to prevent leaking). I then attached the decking boards atop the these runner boards (no plywood!). You have to cantelever the deck a bit over the deck support beams so as to allow the open ends of troughs to dump water out. It's relatively easy at that point to catch the water in a spout under the deck cantelever. Further, like I also did, you can fabricate the troughs so that they're pitched to create a high closed end and lower open end. If your using say 2x8 joists you can implement a 7-inch drop. It works, been working at my house for almost 20-years now with no failures. Here is a link that might be useful: Deck Trough Patent (expired)

Hi Scott, Yeah, I thought of that, but we sanded off sticky residue on a sub floor once, and it totally gummed up the sander. This residue stays moist due to the heat and water it is exposed to. DH said scrape it, but I am afraid of doing damage to the wood. I was hoping someone might have had some experience in a product or chemical that would remove the glue. Regarding the latex paint - I am thinking it won't hold up with all the moisture. Whatever we do, I really don't want to have to be doing it again the next year. I'd like it to last a few years. I told DH that I just want to put peel and stick vinyl tile over it - I was thinking we could even put it over the glue since we want it sticky anyway. And, I was thinking we wouldn't even have to remove the other vinyl. The only thing is that the deck is only 21" wide, and most tiles are 12" square, so we would end up having to purchase twice the amount of tile to cover it. Lynne

Unless the problem is identified & fixed, it should be a deal breaker. Follow the money. Who pays or recommends the "drainage person" or inspector. They checked the drains, but what about the water supply. Their could be a leak that is following the pipe into the house. Poorly sloped grading that is directing rain water back toward the house. It could be a sometime thing caused by a rainstorm & disconnected downspout or it could be a cronic problem that won't go away without a lot of money. As nice as the house might be otherwise or how much you like it or the price, be prepared to walk away unless the problem is fixed.