Very simple. Reach down in an open area. Get a good grip on the fibers. As far away from your feet and furniture as possible. Pull up (if you can) and let it go. If it drops like a parachute creating a wave its loose. If it snaps back down like a rubber band its good. And you already know where to look as you just said. Thats a good indicator there might be a problem when wet.I dont have a disclaimer as this doesnt happen too often. What I DO have is an article written by an industry expert which explains in detail why it happens and give the customer a copy. I have never had to do a restretch in 40 years.
Also I dont know how you would prequalify this as if it is laying flat before you start you have absolutely no way of knowing if it will buckle.
yes I do tell people when I see a poor installation usually around door trim etc that they may not be aware of but buckling is something that even I cant see before I clean a carpet.
maybe its something I slept through at the IICRC class?
just fwi not all carpets will buckle (wet) when loose. It depends on the fillers and backing used in manufacturing. Ive only come across a few. The old jutes were the ones that one need not worry. They actually shrink when drying. Some make actually shrink and pull strip out of the floor. The latex ones can lay back down but often the problem still remains with those. I watched a couple guys wet n jet a heavy piece woven back. No furniture no jogs in walls. 2 days later the buckles still remained. Humps all around perimeter over the strip. Humps in center of room. Now that was a pattern. And in defense of the installer. Those can be a bit to stretch while maintaining straight lines around base. So you kind of pick the lesser of the 2 evils to compensate for out of square rooms by stretching more in one area and backing off in others. None the less carpet was flat before they begun. Except for a very slight arch around the perimeter. I saw it. But they just rolled out the machine and had at it lol. I just minded my business and installed the second floor.