trying to put in a wood floor in 2 rooms . I was going to use 1/4" cork then 1/2" ply all glue down ( concrete sub floor) after which put the wood floor down also glue down (3/4") thick. can I just glue down the cork and the floor on top of that instead of using the plywood? Plywood needs to be nailed in as well ? is that safe or will it mess up the concrete?

You should be able to glue down the cork underlayment, then the hardwood flooring. However, going directly over concrete, you should test it first to ensure there isn't excessive moisture. Also, you will need to use the correct size trowel for both products and the same adhesive. I would recommended an adhesive that does NOT contain any water. That would rule out latex and acrylic urethane adhesives. If I can, what is the purpose for the cork? To act as a sound barrier? If so, you could use the floor muffler and float your floor in, thereby saving a lot on adhesive, assuming your hardwood floor can be floated.

Thanks for the reply . I am using Eco Timber Healthy Bond adhesive.Its an amide ester acrylate resin. The cork is to provide as a moisture and sound barrier . The plywood over cork sub-floor construction is consistent with the rest of the wood floor in the house so I was wanting to stick to that. I purchased the cork ,adhesive and ply already

Its 1/4" cork , 1/2" plywood 4X8 CDX, and the glue . Floor is solid 3/4" thick.

How do I test for moisture? can I rent a device?I hope im heading in the right direction

Your whole idea, is going to bite you.

Solid over concrete is bad enough for failures, then add a thick solid ¾ and the problems multiply themselves.

what would you suggest I do ?

Take the nail down "ONLY" flooring back, and find a good engineered for gluedown.

Don't ask the guy you bought the misspecified flooring from. Contact the mill that produced it, and get their procedure & protocol, for a direct glue over concrete using cork as an underlayment.