I'm replacing some carpet with "luxury vinyl plank flooring" (at $2.99/sqft from Menards, I'm surprised it's not marked "extra luxury" ).

The "installation instructions" are very limited. It does say it's 100% waterproof, though, and has a "built in pad".

Is it common practice to install a vapor barrier under LVT when installed directly on concrete? The instructions don't call for it, but my concern is that the slab seems fairly damp, and while the carpet probably let a lot of moisture dissipate, will the LVT trap it? In that case, I'm not sure it's any more preferable to trap the moisture under a vapor barrier...