Solid Hardwood, Engineered and Laminate Flooring - Solid wood hardwood and noise insulation on a condo

My husband and I bought brazilian cherry solid hardwood to be installed on our condo. The thickness of it is 5/16" -which is pretty good-. We have concrete backerboard subfloors. The problem is that the HOA won't allow us to install it unless we put some kind of insulation underneath. We have asked a lot in home depot and flooring stores, but all of them tell me that noise insulation can only be used on floating floors. The hardwood we bought can be either glued, nailed or stapled, but not floated. What can we do?. Some people have suggested that we put 3-1 foam, then plywood, and then, glue or nail the hardwood. The problem is the thickness of all that. I was searching online, and found this website http://www.soundprooffoam.com/insulayment.html , but I am not so sure about how good the sound proofing is, or whether is better to nail it or glue it down. All your help is greatly appreciatted.

Gluedown a thick cork.

Then gluedown your wood to the cork.

When we bought the hardwood, they told us that we should use a urethane-based glue. If we put cork, can we still use the same glue?. Also, I was checking online on this website http://mantoncork.com/underlay.htm, and it says that cork is recommended for plywood subfloors, but not cement backerboard. Is there a particular kind of cork to find?. I have went to all the specialized stores in the area, and no one sells cork underlayment. Guess I have to buy it online :coffee:

1/4" roll or sheet cork underlayment is common. In this case Bostik urethane is used for both the cork and the hardwood. No shortcuts. Find someone knowledgeable in this application. Otherwise you'll be replacing everything.

You could try this product if you're having a hard time looking for cork underlay:
www.xxxxxxxxx.com

HOAs have guidelines regarding sound transfer. Try to print out the file on sound rating and show it to check if this is the right product for you.

Hope that helps.

You have a concrete sub-floor...so don't forget to install a vapour barrier on top of the concrete.