Floor Muffler's website says it can be used as underlayment on wood and concrete subfloors. I feel I need to use it on my concrete sub downstairs and want to use it upstairs to kill noise. If I do, do I still need to put tar paper under my nail down floor, or is Floor Muffler alone OK?

Thanks,

--David

I'm not sure how effective it will be as a sound deadener on the second floor. Does Floor Muffler allow for this type of installation (nail down)? You would not need additional paper or felt if floor muffler approves of installing a nailed down floor over their underlayment.

Generally speaking, most of the effectiveness of a sound barrier is lost when fastneing through it.
It will however, increase the sound qualities within the area it is installed. For this reason, we quite often install a 3 m.m. cork underlay even for standard nail-down applications.
Whether you should use it on your second floor can only be determined by your budget and if the sound deadening qualities for the main floor will be effective enough to be worth it to you.