Should I go with 15 or 30 # felt if I live in area with high humidity in area over crawlspace? Also I am going with pre finished 3/4 Bruce hardwood. Can I run felt in same direction as hardwood? Do I overlap or butt edges together and what do I secure felt with? Are staples ok?

Thanks for all of your help

Lets talk about the crawl space first. Have you taken proper moisture control in the crawl space? Plastic moisture barrier over the exposed soil? Humidity levels controlled?

A pin type moisture meter to check the subfloor& the flooring, is in your best interest.

If you have everything in check, it won't matter which one you used.

I wouldn't run 30# the same way and overlap it! You will visually see the hump in the prefinished floor. 15# is bad enough for me not to do that.

I only staple the first run down, to keep it from moving and messing up my popped chalk line. The flooring will hold it down from then on. I do get mad at it toward the end of the roll and it wants to roll back up on me. A couple staple near the end walls takes care of that.