QUESTION

Is a mortar bed a sound control barrier? I want to lay porcelein tile in my condo which is in a hi rise. The condo association requires a sound barrier although they did not specify any noise reduction requirements. I did get the President of the board's permission to use instead, a 1/2 inch mud bed. Still, I worry that later when I sell it, there could be a problem. I have priced may underlayments but they are too expensive and substancially increase the cost of the install. Most are over $ 1.45 per SF. Will a 1/2 inch mud bed muffle sound between floors or do you have any suggestions or know of a less expensive product. Thanks in advance and I look forward to hearing from you.

ANSWER

ANSWER - Using a mud bed (cement) does not reduce the sound, but might amplify it because it is a hard material that transmits sound.  You need a sound barrier that will limit sound transmission.

There are a whole lot of exceptions and considerations in specifying a floor to ensure you achieve the kind of results that will provide a successful installation with a reasonable IIC (Impact Isolation Class) rating and a STC (Sound Transmission Class).  But I will give you some brief suggestions, although I would suggest that your Condo board should consider retaining our services to ensure your tile installations meet codes and perform as intended.  Failures are much more expensive than spending the money to do it right.

Assuming you are installing over a concrete substrate.  First prepare the slab correctly by flattening it out by grinding high spots and filling low spots.  Then either use a 1/2" cork sound control mat or a 1/2" rubber mat made for bonding to the concrete slab and then made to allow the tile to be bonded to its surface with an approved thin-set mortar.  Make sure the mat is also applied up the wall at least 3 inches along the perimeter of the room.

The performance of this system will vary depending on whether the room below has a drop ceiling and how thick is the concrete slab.