Does anyone have an opinion on the relative merits of red rosen paper and black roofing felt? It seems most people are using the roofing felt, but our wood supplier is recommending red rosen.

You'll get different opinions everyday on this subject. Some swear by red rosin and the same for asphalt felt paper. I've actually heard rosin paper can absorb moisture. Anybody else hear the same?

I'm trying to find out what to use under an engineered floor that will be nailed over radiant. Any aspalt paper product concerns me regarding odor off gassing from the warm floors. I was considering the rosin but now you got me concerned about collecting moisture. What else is there? We have your basic #15 asphalt felt, all the various Aquabar products (which most, if not all, use asphalt to a degree) and red rosin. I guess I'll have to research a little harder to find the ideal paper (if it is paper) underlayment between radiant panels and wood flooring.

In my case I am installing 3/4" hardwood over 3/4" plywood, over a full basement, in the mid-west. No radiant heat, just forced air heat and A/C.

I heard from some installers the rosin paper dosent do that good of a job for moisture .. Its main use is to quiet the floor .. [for what its worth ] .

I have yet to be convinced that 4 mils of paper under the floor does anything at all. 15lb felt is a tried and true retarder, but even it doesn't offer much protection against sudden rises in humidity levels underneath the assembly. For me, Aquabar is the smartest route to take. The cost is minimal when viewed from a cost per square foot perspective. It is really a great product. It is also very installer friendly.(no marked walls)

heard good things about aquabar .. going to give it a try .. What cost more /
aquabar , or a new floor ?

Thank to all for the good advice. I will return the Red Rosen today and look for Aquabar, or failing that, get black asphalt. I have not been able to find a source for Aquabar.