My LVT doesnt have a pad, and the underlayment I have was for laminate. I have seen at Amazon that some have used a 3 mm foam underlayment, which many reported as spongy, but I thought the felt would be less compressable and less spongy, just a bit concerned about moisture over time, I guess...
I did a 48 hr moisture test and the concrete is dry (40 years old, but partly below ground level.)
I have 5.5 mm engineered vinyl planks.
I also have some leftover 3 mm and 4 mm felt underlayment with a vapor barrier attached.
I read I should use a vapor barrier over concrete, but the...