^^^^^^ that is correct^^^
also
Sound damping materials may be used to reduce vibration when installed in accordance with the manufacturer's recommended installation instructions. The maximum total thickness of sound damping material applied at any given location may not exceed 5/32 inch (4mm). The sound damping application may consist of mat-type material, spray-on material, or a combination of the two. A maximum of 2 layers of mat-type material may be used at any given location, even if the total thickness of the sound damping material(s) is less than 5/32 inch (4mm).