What is the recommended underlayment for 3/4"x 2 1/4"red oak hardwood install.

I have searched and found conflicting answers.

I prefer 15# felt because it stays put better. The thinner papers rip easily and bunchs up.

15 Pound Felt.

IMO Red Rosen Paper serves no purpose under a hardwood floor. It serves a purpose to a certain extent , for covering the floor to protect it after installation.

How will the 15lb be better?? Moisture control??

If you get loose boards over time will you start to hear the stick sound like when you step on the 15lb if its exposed??

NWFA states, " Before installing wood flooring, place an approved vapor retarder. Some examples of acceptable vapor retarders over wood subfloors include".
1) An asphalt laminated paper meeting UU-B-790a,Grade B,Type1,Style 1a.
2) Asphalt-saturated kraft paper or #15 or #30 felt that meets ASTM Standard D-4869 or UU-B-790, Grade D.

IMO the felt is a little added vapor protection, but very little. I use it to be within the standard. I do like it for ease of installing the wood ,as Got Wood mentioned. I also believe it has insulation properties, ( but very very little,it's very possible I'm pushin it on that one ), also a better feel under foot, ( than wood on wood).

Red rosen is a cover paper, period.

Also, you should not " get loose boards over time", if installed according to today's installation procedures.. If you did get loose boards, you would not hear the felt, but you might hear creaking and squeeking.