We are in the process of putting in hardwood floors ourselves (almost done....yea!). Our flooring came from the house I grew up in (it has been torn down) so first we had to go and pull up the floor boards carefully, clean them, and now we are installing them. Long process. What you put down under the floors depends a lot on what type of subfloor you have as well as what is underneath the subfloor.....do you have a slab, is it over a basement, is it over a crawl space......is what it is over a damp environment or a dry environment, etc. Also, are you putting in actual hardwoods or engineered/laminate flooring. This also affects what you put under the flooring. Now the house we took the floors out of was 40+ years old and back then they used what was basically huge rolls of waxed paper. So it kept moisture from below out, but if anything was spilled from the top....well, we discovered some pretty nasty stuff that had been trapped up under the boards between the wood & waxed paper. Also, they weren't very careful of getting all of the subfloor covered completely....there were a lot of gaps in the waxed paper....so make sure whatever you use that you cover things completely to avoid problem areas. Personally, what we are doing (based on our particular situation with our house......without knowing more about your situation & your house I can't say as to whether or not this would work for you) is using the laminated red rosin paper. We are laying the floor over a wooden subfloor. The area underneath is a basement that is extremely dry (has never had water/moisture issues in 13+ years since the house was built) and the house is located in an area where the lot stays dry (no standing water issues) as well. This will allow breatheability of the wood and (hopefully!) any spills that may occur to dry out as well without causing any mold issues. One thing that had been suggested was felt paper (like what goes under your shingles on your roof) but it was for if we had been laying the floor over a damper area (like if it was over a crawlspace that was prone to moisture issues to prevent moisture from coming up from the bottom).....which was not the case in our situation. I hope this information has given you some help.
But we definately have humidity in northern Virginia!
