Hi, I'm about to nail down some 3/4 oak hardwood and I have a low spot ~ 1/4 inch plus minus a 1/16 in sub-floor (3/4 osb) in a corridor with area ~2x2 feet. I looked at forums and people recommend shingles and 15 pound roofing felt...
I put in 1 layer of shingles and then tar paper to smooth it out and make it perfectly straight... Well I ended up with 13 layers of 15 tar paper in the lowest spot on top of 1 layer of shingles. After that I read a manual for hardwood and they say maximum is 6 layers of 15 pound tar paper. I couldn't find any topics with the amount of maximum layers. People just say multiple
What's the maximum number of layers? Is it what manufacturers say or could there be more?