I did a search on these forums for green glue which seem to flood the market with marketing of their product. I can't seem to find anyone with real world experience though.

I have ~900sf of 9/16" engineered being NAILED down (bamboo hardwoods hybrid honey - product #55812). It is on our second level on a 1969 house with 16" OC ~11" floors. Subfloor is currently 5/8" (might be 3/4") Plywood. In order to bring the hardwoods up to adjoining surfaces, we are adding a layer of 5/8" t&g plywood.

I've looked at adding the sound deadening "green glue" between teh two layers of plywood before hte flooring goes down but I have not been able to find anyone with real world experience on how well it works - it would be ~$600 in materials alone for the green glue, plus a little more in added labor.

Anyone have experience with the Green Glue and know how well it works?

Was also thinking of adding 1/8" cork between the two layers of t&g plywood and dropping second layer to 1/2" t&g plywood to see if that maybe would work and be cheaper/easier to install? Reason for going in between layers is that we are nailing down so cannot have the cork and then hardwoods right on top as far as I understand.

Any other sound deadening options while upstairs is under construction (short of pulling existing subfloor to insulate etc)?

Regards,
Matt

Probably to late but Sika Acoubond system is a tried and true method of an acoustical dampening system used for years.

Old thread, but for future reference for people I have a good online source for cork underlayment. Tell then I sent you ;
www.flooringstoreonline.com