Has anyone had any experience with a soundproofing membrane that goes under engineered hardwood and claims to reduce footfall shock sound from traveling between levels?

I have rebuilt the walls and have coated with redguard (the pink paint), which acts as a waterproof membrane. 

Moisture resistant would be ok for above the shower where you don't expect water to run down or even splash.For the back of tile, however, you need Redguard applied to Duro-rock or similar tile backing material to create the moisture-proof membrane you want.

A jackhammer and a five gallon bucket does the trick - lol - a concrete saw if your picky about a perfectly straight line.If you also have a block foundation, I suggest also installing weep holes in the block cores and installing a membrane over the wall and down to the footing.

rich23s, Home Depot sells a product, it comes in a roll, its orange in color, its flexable plastic, it has little squares imbossed in it.....Sorry I cant rmember the name, but its in the tile and flooring area, ITS slick, put your floor prep down, lay the orange membrane over that, let it cure, come back tomorrow, lay mastic and lay tile.

You may only need to use them in the stubborn areas.Also, if the floor is a large area such as a 2 car garage and or has any cracks, you'll want to put down an isolation membrane first. this will keep the cracks from telegraphing through your tile.

The manual could have a copy of the building permits pulled, photos of construction in progress and cut sheets of construction assemblies/standards used during the project.For example, if a bathroom was remodeled, take pictures of the waterproofing membrane, provide product specifications, maybe even provide a mockup for the homeowner, so they know that everything was done right and by the book.

The only other advice I'd have, is to be sure to use a waterproof membrane on the shelf, so water won't sit and soak into the framing.What did you end up doing on this project?

The flipper saved $500 on the roof, 2 years later I have to tear it off and replace it with a membrane, plus take the soaking drywall down an deal with that mess.

Here are a couple progress pics, before is barney purple, ignore the glowing pink from the anti-fracture membrane: