I am thinking about using a 6 mil poly and a thicker sound/water barrier to make walking on the floors a bit softer. I plan to tape (or use silicon) as a means to seal moisture.
My question is, is it a good strategy to completely seal the floor like this? Judging by my crawlspace (which is sealed with 6mil poly), droplets gather underneath. Wouldn't the same happen for my insulation under the hardwood? Would it damage the concrete?
Use a combined moisture & sound deadening barrier like Roberts Unison 2-in-1. I put this under my engineered bamboo floor. It was an easy install and works great.
You can use a full underlay that includes cushioning as well as moisture barrier. There are also underlay options that will slowly absorb any moisture the concrete sweats and slowly release it in a way that does not harm your floor.
Most floors will need something that has a moisture barrier and cushioning for the warranty to be valid so be sure to have at least those two components.
You can find more information at the BuildDirect learning center link below: https://www.builddirect.com/learning-center/flooring/laminate-flooring-underlayment/
This covers laminate underlay but they will also work for floating engineered hardwood
