Here are a few options: 1) If you'd like to nail it to plywood, install FloorMuffler over the plywood. This is a sound proof, moisture protection accoustic underlayment. 2) If you'sd like to glue down, use Taylor MS adhesive. It has a 25% noise reduction. Best Installation: Nail over plywood with FloorMuffler. My kind regards...

I understand the sense of caution. Callbacks are not good and can eat away at your profits. To answer your question: I have used products supplied by flooring distributors, and have included products from Ardex, Mapei and Fritztile. They were all used with an appropriate primer to facilitate bonding to what they were placed over. Additives were included to make the product less-likely to break apart and powder. I especially like Ardex SDP (Self Drying Patch)...because the PSI (pounds per square inch) rating is lower than some other products. Self leveling formulations can achieve a very high PSI and can be very difficult to nail into, even with pneumatically assisted fastening tools. When I used a product with a high PSI, I sometimes would have to drill pilot holes and manually drive in hardened spiral flooring nails. I never had a floor patch crumble. I figured...if I used a good patch, and if the substrate was well-fastened and didn't move much, I believed the installation would be OK. I believe that you have to have significant movement to get a decent patch to fall apart under a finish product. I came to wood flooring out of a family business that specialized in resilient flooring materials, so I learned a lot about what you can and cannot do regarding floor patches and their application. I will say in closing here (for general consumption) , especially for the DIYer,... if you try to use calcium carbonate patches (usually white in color...and I won't mention brands) ...you will experience quick breakdown of the product, because they are fragile and will crumble easily. If it looks like plaster of paris, it is not a suitable floor filler or patch...my opinion.

Yes, it is being installed perpendicular. I know it's not the ideal... but in the interest of time and budget, it's what we've landed on. We are likely going to do an engineered floor on top, to eliminate a little bit of the extra height. I would (just for my own knowledge on what to expect) love to hear the cons of this method, even if we're likely to do it anyway :) And it is a wood subfloor - so just add plywood ontop of that until it becomes flush is what I'm hearing. Thank you!

So what are you having as the FINAL floor? It sounds like you are installing 1/2" cork FLOORING TILES....but then a little further on you are talking about wood over cork. This tells me you are talking about cork UNDERLAYMENT underneath hardwood. OK. Now we are on to something. A vapour barrier is required if you are AT GROUND LEVEL or BELOW. Your installer can glue down the cork to the SUSPENDED SLAB (aka....10th floor concrete slab) without worrying about a vapour barrier. A sheet vapour barrier is NEVER USED with glue down anything. The glue must act as the vapour barrier. Glue down hardwood over glue down cork underlayment is a MAGNIFICENT floor. And it is one of the MOST EXPENSIVE installation formats for hardwood that we have (yep....it is more expensive than you can imagine). If your engineered wood can be FLOATED then you will save HUGE amounts of money (could be as much as $7 - $10/sf worth of savings). The cork can be floated (it just sits there....no glue) and then the wood is floated over that (glued at the edges and tapped together). It is a MUCH faster installation (can be 2 days faster). But first: what floor do you live on?