Which Sound Barrier to Use?

Sound Barrier to Use? — modern flooring photography" width="1200" height="675" loading="eager" decoding="async">

Q: I purchased 3″ wide 5/16″ T&G engineered flooring to be installed floating on a cement pad. I also purchased sound 6 barrier II and Poly vapor barrier. A professional installer suggested that I will not be satisfied with the sound barrier I purchased because I will still have sound. He didn’t suggest anything particular to use. Can you give me advise? I have read a lot of the suggestions you have provided to other customers and it seems that cork underlayment might be a better way to go.
Should I stay with the sound 6 barrier or go with either 6mm or 3mm cork? I don’t want the flooring to be noisy but I don’t want it to be spongy either. If I use cork do I need to install the poly vapor barrier prior to installing the cork underlayment?
Thanks for your help.
Terry
A: The combination underlayments, such as 2-in-1 and 3-in-1 feature a very thin foam underlayment which is nowhere near as dense nor sound dampening as Sound 6. Plain and simple, combination underlayments are cheap, great from an economical stand point, but from a perspective of giving your floor a good sound and feel under foot they are nothing when compared to cork or a well design modified, closed cell underlayment like Sound 6.
Sound 6 features the some of best STC and IIC ratings in the industry and no combination underlayment can hold a candle to it. STC ratings for your typical combination underlayment is usually in the mid to high 20s where as Sound 6 has an amazing STC rating of 73 (that’s more than 6″ of concrete in equivalence).
Sound 6 is a great underlayment, but you may feel some movement depending on the amount of traffic on the floor or the weight distribution over the floor. Now if you feel movement it will be very slight and not really “spongy,” but if you really want to ensure your floor feels solid under foot then you may want