Man what a drag!! I love that area just reading about it.

Nix on the drylock and the plastic for a lot of reasons. You need ventalation to the outside google up FanTech. These units are almost undecteable while runing,move a lot of air , last a very long time and can be mounted any place.Might be a good idea to provide air coming in while the thing is running.

Down side it will remove the heat in the downstairs room as well.

Garapa is less forgiving than ipe but try this anyway. Without the pool runing and ventalation is going on run several big fans up toward the decking and on top of it for a week or so. I have had ipe T&G with cupping problems completley flaten out with air moving around it. JonMon

I've been thinking about this a lot... I've got 2 conflicting goals here: 1. temperature and humidity equilibrium above and below the deck so there's no cupping, and 2. toasty warm air below the deck so I can swim.

So I can ventilate downstairs to achieve goal 1, but it will make goal 2 impossible.

How about a bunch of floor vents in the garapa to promote air flow plus a vapor barrier under the joists? In theory, pool room would be warm-ish, but deck would get equilibrium. Or should I look at glassing in the screened porch, again with a lot of floor vents to move air between the bottom and the top?

Couldn't sleep last night - husband is upset, cupping keeps getting worse - right now my pool room has open windows and a fan to dry out the garapa, but it's probably 20 degrees in there!

Also, the cupping started when it got cold out - I'd think the vapor barrier could be a winter-time only fix, taking it down for the summer, which might cut down on mold and such?

Hmmmmm...let me get this straight above the pool is a grapa deck acting as a floor for a screened porch, below this porch is a glassed in area with a heated pool. With the pool running and the cover off the steam drifts up to the garapa decking. Because its cold unstairs and pretty warm downstairs the garapa is warping.

There is no roof under the garapa decking so when it rains the water gets thru to the pool area. This about right? If so it must get kinda bad under there when the snow melts and during a big rain.

If so that is the design flaw a torchdown roof should have been installed upstairs with the decking fastened to stringers laying on it.

It might be possible to seal in the bottom of the joists with say 1 1/2'' sheets of styrofoam sealed up with alum tape and covered with panneling. Buttttttt....all the water coming in thru the decking would collect in this covering Not good.

Or this is all wrong there is a roof over the upstairs area. J.

Okay, I should post a picture... Yes, there's a roof over the upstairs area. It's a covered screened porch over a glassed-in pool room. The garapa t&g floor from the screened porch is the ceiling for the pool room. Yes, water comes through the garapa floor into the pool room, but not much. It didn't seem as though it would matter - the pool room was designed for getting wet.

Here's a photo of the back of the house. Screened porch over basement-level pool room.

Here is a link that might be useful: back of the house

As long as the steam gets through,in the winter at least,the decking is going to react the way it is.

All solutions require removing the decking or living with the movement. Remember dont shoot the mesenger.

J.

It's really quite simple...wood and water don't mix, and the water is in the humidity.