Best option for felt paper?

Q: We are installing 3/4 solid Brazilian teak in our home and are wondering about the best option for felt paper. The stuff sold in the flooring section looks cheap and thin so we are considering using either #15 or #30 roofing felt paper. What would you recommend?

A: #15 Is fine. These underlay papers, even the ‘cheap’ one which was probably wax coated are meant to facilitate movement of each row of boards into place when installing and to ‘retard’, but not prevent moisture movement through the floor.

Similar Q: I am putting hardwood floor down. I took out 3/4 chip board and replaced with 3/4 spruce. Do you recommend placing 15# felt between the subfloor and the 3/4? And another between the 3/4 and the hardwood? To prevent squeaks?

A: The felt or roofing paper is meant to serve as a moisture retarder and it would go on top of the plywood which the hardwood sits on. It is not meant to stop squeaks. If the plywood is screwed down into the floor joists and is reasonably flat, and the hardwood is nailed down every 7-9 inches there should be no squeaks.

Follow-up Q: Wood flooring guy, Should the 8 x 4 underlayment sheets also have a small space between the sheets for expansion?

A: If it makes you feel comfortable you can leave a tiny gap, say 1/16″. Keep in mind, the way plywood is constructed, it is by design dimensionally stable with wood ply’s running in opposite directions and joined together with water proof adhesive.