It is absolutely not recommended and anyone with any sense should tell you no way . If you pressure a manufacturer real hard, they will at times say that it is ok as long as all moisture test are taken. Moisture must be basically non existent. I will not allow any of my stores to install 3/4 solid on concrete. They'll buckle so easily. That's what engineered or thinner solid floors are for. It's not worth the risk. Sorry

Echo is right. Especially with a dense species this is a crap shoot. And the comment about the slab being dry only applies if you have a good moisture barrier under your slab. What I mean by that is if you take concrete readings and determine your slab is dry that only means it is dry at that time if you don't have a plastic barrier beneath. I've seen a lot of concrete contractors cutting corners and not using it in different markets and they are telling their customers that they have an additive in the concrete that keeps it from wicking moisture from below. I'd be very careful. Either use a product made to be glued to a slab and use a moisture barrier or deal with the height difference and make sure you get a good barrier on top of the slab. My two cents..

realwoodfloors.com

Thank you for your help.

Inspector - What type of barrier do you recommend when glueing down engineered wood flooring over contrete/radiant heat subfloor?

Thanks