Dynamat / Peal n Seal... yes or no

Anyone of the materials that go under the carpet, even jute, have the potential to trap moisture so I would be looking to fix the leaks before putting down a noise deadener.

That being said I used a rubber like material that goes down under roofing for the first few feet that acts as a water barrier, it has a sticky backing. Not sure if it's asphalt based or not but it has been out in 90+ degree days for several years and has not melted or smelled. The stuff is quite dense and has done a good job of quieting down the car. Don't know how it compares to Dynamat or one of the other car specific materials but $40 for a 50 foot roll seemed to be to good a price not to give it a try. I also have a layer of jute under the carpet, back seat and under the mat in the trunk.