I am installing 3" x 1/2" Engineered flooring over a concrete slab and now I'm not sure what method to use. I am on the island of Guam.

I was going to use 3/4" plywood at 45 degrees and ramset it into the concrete, over a layer of asphalt mastic and 15 lb felt. then I was going to lay a 6 mil polyethylene vapor barrier and then staple the 1/2" engineered flooring through the plastic. (2600 sq ft). I am also considering the SIKA vapor barrier system over the plywood, or by itself without the ply.
http://www.sikaconstruction.com/con/con ... fb-sab.htm

The reason I am doing this is that I am on the island of GUAM and the humidity is very high here. The house is a 3rd floor condo on the beach as well. It is an old building and the concrete is dry, however.
Termites have eaten the old wood flooring from underneath; also engineered wood, which was glued down. I will treat the termite problem first. should I use treated ply?

I am also considering floating the entire floor, with the flooring nailed to the plywood. Is this a good option? will it move or creak? could I glue the plywood and have a level enough surface. I know that I have to use a high grade plywood in order to do this. Should I cut the ply into 16''x4' strips? etc.

Given the climate situation and the proximity to the ocean: DO I NEED TO DO ALL OF THIS THIS? OR CAN I GLUE IT TO THE CONCRETE WITH SUCCESS? (perhaps using the SIKA system).
The cost and time are not the biggest concerns on this job (for once). I want it to last and not cup or seperate.
I have read some of the other posts related to this same issue. So, no need to repeat yourself. I'm still not sure which options I should use in this situation.
Thanks A Lot for any help.
Eco-Solutions Building

You should never use treated plywood for this. The only treated plywood that may work Is KDAT (kiln dried after treatment). Even then it will be around 16-18% and would have to air dry on site.

Can you not have the concrete termite treated then just glue the flooring down? I don't know the answer to that....

thanks for the reply,
I had the same thought that the moisture in the PT ply wouldn't work, but I am still figuring out how to solve the termite problem. I am definitely going to have the pest control do a whole house treatment before the install.
The main issue is the moisture from the concrete affecting the glued down flooring. At this point I am pretty sure I am going to use 2 sheets of 1/2" plywood over a vapor barrier of 15lb felt paper, 6 mil plastic, then more felt. this will float, and then I'll staple the flooring to this, making sure not to penetrate through the vapor barrier. I would really rather nail the flooring than glue it to the concrete, because I am more comfortable with this, and I think that it will produce a better install.
thanks for your help.

The subfloor you describe sounds good, even if a bit of overkill.
Lay the bottom layer of plywood down over your MB running the sheets longitudinally leaving 1/4 inch spaces around each sheet. Lay the top layer on a 45 degree angle, glued (we use parquet adhesive)and stapled to the first layer.
You now have one giant piece of 1 inch plywood as a sub-floor.

I would float 2 layers of 3/8 plywood stapling the top layer to the bottom and run the top 90 to the bottom with 8 mil plastic under it. Then nail it. Have the pest control guy soak that concrete and the perimeter.

What species of termite is it? The ones in the U.S. won't eat Mohogany, so you might just as well get a solid and nailer down.

Another alternative is laminate, they wont eat that either. If you have a really bad termite problem those little buggers can find a way in.