Hi - I thought I was going to be dealing with "real" concrete so I bought an engineered glue down bamboo because the price was right as well. I pulled up carpet today and saw that the "concrete" was really this soft thin layered stuff. I could even see space where wood was visible where the closet met the hallway area.

I am only putting in about 280 sq feet. I thought I was going to glue the tongue and grove bamboo as I did in a previous installation where it came out great but that was real concrete.

It sure looks like they treated this just like straight wood subfloor with the carpet I pulled up - many staples were in the padding right in the concrete (although some were not really "in" and some were but the staples did not seem all that hefty).

I am thinking that I may be able to do this as a nail down but not sure how to approch an underlayment to go over this soft concrete job in an upstairs condo. I really need to keep my cost down as I am already over budget.

Thoughts - experience - suggestions please?

Until you really know what you have it would be a little risky doing the install. If I ran into this situation I think I would drill some 3/4 inch holes in various places so I could see the thickness and composition of the sub-floor. I would fill the holes back in with 3/4 inch dowels dipped in carpenter's glue. I would at least know what I am dealing with before proceeding.

Your probably looking at gypcrete. http://flooringblog.bostik-us.com/2009/ ... oirng.html

Check your bamboo manufacturer, you can float quite a few bamboo products using T&G adhesive. Floating over qypcrete isin't any different than floating over concrete.