lbbs,

You might want to ask this in the audio groups since recording and sound
isolation go hand in hand. I agree with Mr. Ransley that the clerk in a
hardware store is not likely to be any help. Be sure before you start
looking for solutions that you know what the problem is though. An insulated
room will not admit sounds from outside but may still be a "noisy" room if
it is highly reflective.
Sound can and will travel through hard tile

Good luck,
Dave M.