Laminate flooring buckling

[retgi]

My girlfriend's house has laminate flooring installed on a concrete slab in Homosassa, Florida just north of Tampa: Pergo accolade rustic oak with padding on back side throughout most of her house. She had it installed about four years ago by installers while she was at work. The store where she bought it has since gone out of business. Since we've been together about six months now, I've noticed a lot of creaking when walking on it in cert and more and more slight buckling at the joints in all areas where it's installed. I checked the perimeters to ensure there was an expansion gap and that's about 1/4 to 1/2" in most places but lifted up flooring to check for a vapor barrier and couldn't see any at all. So my question is, in order to lay a vapor barrier which I believe should have been installed, do each of the planks have to be separated or can I separate in 6 or 8 ft chunks (is that even possible?) to make it easier? Also, is there anything else I would have to do or be made aware of prior to relaying this floor? Thank you..

 

[Ken]

If the laminate has already been affected by moisture it wont return to normal even if you were to pull it up and lay a vapor barrier under it.

 

[Floorist]

How flat is the slab?

 

[Ernesto]

Attached cushion products need 6 mil under it over top a slab. Even some of the cheapo all in one rolls of cushion/vapor retarder need it as well. It only buckles when its locked in.