Solid Hardwood, Engineered and Laminate Flooring - New Install Preparation Q's

Hi,
I have been finding and hearing conflicting information, so I thought I would pose a couple questions here for some info.

I am installing laminate floor in a second floor condo on concrete subfloor. Some have said that I do need to lay down some poly as a vapour barrier. Some have said I dont want to lay it down, being above grade on the second floor, since it may actually cause condensation buildup under the poly due to warm air getting trapped. What is your opinion?

The second question relates to using a self-levelling compound to fix a dip in the middle of the room. I have heard that I should use a primer on the concrete prior to pouring the compound. Is that always necessary? I know, I know... "follow the manufacturer's instructions", but why would it be needed?


TIA for any info.

I don't care if it is the bottom floor or the 100th floor, if it is concrete, you better put a moisture retarder under it.

Moisture is what keeps concrete from cracking & crumbling turning it back into a powder. Concrete will always have vapor emissions, no matter where it is.


If this is gypcrete(lightweight mortar pour), you can't use a portland based leveler. This stuff is usually found on upper level suspended concrete, for weight purposes. It can be very unstable.

Some say prime, some say they don't need it. Ask the manufacturer of the product you use.

Thanks for the input.