extra underlayment for laminate with preattached underlayment
 

Hi,
We bought the costco laminate with preattached underlayment for first floor that is concrete slab. I am thinking to put an extra layer of underlayment for better insulation. I was recommended to use "selitac underlayment".
I wonder would the extra underlayment cause any problem in the long run? 'Cause I image the floor would not as freely to float because the friction between the layments. If yes, what is a good way for extra insulation? If no, is selitac a good choice? It is about $50 per 100 sqft.

Thanks

Selitac provides a better thermal break. It is designed to be used under laminate with an existing underlayment so there is no friction issue. You do want to make sure that a rolled underlayment does not overlap the seams in the Selitac -- alternate the seams for better sealing and strength.

Go here for more: http://shawfloors.com/About-Shaw/Shaw-Advantages/Selitac-Underlayment