Hardwood floor underlayment

Hi Ron,
Our flooring supplier sold us on a dense foam under layment. The foam would negate the need for the felt. IIRC, it was 1/4” thick. Even so, we needed two transition strips. They do come in different configurations to compensate for different floor elevations at doorways.
We had two areas where the floor had sunk a bit. After insuring it wasn’t going to move more, we did use felt to feather out the dips.

-- Gene 'The true soldier fights not because he hates what is in front of him, but because he loves what is behind him.' G. K. Chesterton

No problem adding 1/4 inch underlayment to make floors even. Are you putting down 3/4 inch wood. If you are stay away from any foam underlayment. That is for floating floors.
You can use rosin paper or 30 # roof felt between underlayment and new wood flooring. Take your time and Good Luck.

YOU ARE CORRECT dbol!!!!!! Good catch
I failed to mention that ours is a floating floor.
I’m sorry if I misinformed you Ron.

-- Gene 'The true soldier fights not because he hates what is in front of him, but because he loves what is behind him.' G. K. Chesterton

I would suggest a good adhesive between 3/4 ply and 1/4 ply and screws. Will prevent future squeeks !

-- "My mission in life - make everyone smile !"

I think the 1/4 inch ply would work OK. I agree with canadianchips that you want to be sure it is glued and screwed so it doesnt squeek. I would use rosin paper under the hardwood floor for the same reason.

-- Wayne - Plymouth MN

+1what Wayne said.

-- -Zeke- "I hate to rush off, but I gotta go see a man about a log"

Thanks!

I’m ready to get this project rolling. Now I just have to think of any new tools I need to get the job done.

-- Ron, Northern Illinois

More tools.
Thats the correct ATTITUDE ! LOL

-- "My mission in life - make everyone smile !"

Had some rosin paper. Yesterday bought the ply, adhesive, screws…., and a pancake air compressor

-- Ron, Northern Illinois

Just a note with the 1/4 ply… Make sure you lap all of the seams in the subfloor below by running the sheets perpendicular to the existing subfloor and offsetting the starter run. Though I have not done this to raise the height for a hardwood floor, I have used this technique many times for vinyl, linolium and engineered flooring requiring leveling and stabilization. To prevent and elimiate squeeks, I typically use rosin paper between the subfloor and sheathing and ringshank nails spaced 4” around the perimeter of each piece and 8” spacing in the fields. I your case, I would use rosin paper again between the sheating and the hardwood.

And as another note, I only use subfloor adhesive on the floor joists when laying new, or replacing the subfloor. I would not recommend it between an existing subfloor and the sheathing for a multitude of reasons, including creating voids which, once the adhseive has cured, could actually cause more squeeks than it prevents. Further, even though it may never be necessary to redo your work, once you put on the adhesive, removing that sheathing becomes a complete tear out and messes up the entire deck. It is like glued on carpet. Anytime you put something together, think aboiut the guy who may have to come and take it apart or repair it down the road.

-- http://www.whipplesargent.com/dwnlds.htm#whipplejigs