I am finishing my attic and have just completed laying the OSB subfloor. I plan to use this space as a yoga studio for my wife / guest room for family / playroom for my child. It is directly over my bedroom so I want to make it as quiet as possible so I am planning to put a thick rubber underlayment before I put down a laminate floor. Are there any things to consider when putting the underlayment down? For example, a vapor barrier, an extra underlayment for the laminate flooring, whether it needs to be secured down?
UPDATE: I ended up going with a much thinner underlayment which I installed first. I also purchased the laminate with an underlayment backing adhered to the underside of the laminate which seemed to be equal thickness of the extra underlayment I purchased. The result has been great. There is very very little sound transfer from the floor of the attic to rooms below. I have no practical experience to back this but I would be a little worried the thicker underlayment might make the floor too squishy.