So I am going to lay a solid core vinyl planking over a concrete slab. The slab is level and well seasoned (cured) was told I don't need to put anything down. But am wondering about putting something down that will provide a little cushioning. I realize it is a floating system so that may not be a good idea. Just wondering what my SF expert would have to say. Thanks guys and gals.

I used a commercial vinyl plank in my son's room to test it out for future use. Figured if anybody could tear this stuff up he could, and so far it still looks like new.

The instructions specifically said to install it directly atop the floor. I don't know if this is specific to this manufacturer or product, or if it's the same across the board. They didn't want any padding or vapor barriers beneath it.

Yep, read the manufacturers install requirements. If there is ever a warranty issue, the install will be one of the first things they check. Some LVP has a “pad” built in to it, recommends looking around to see what you can find.

Selitac makes an underlayment for under floating LVT/P as well as laminate or wood that's around $.50 per square foot. I don't know how much R value it gives, probably not much but at least some. It's main function is it functions as a vapor barrier and sound deadener (most noticeable under wood or laminate).

Oh and for under LVT/P nothing thinner than a 3.2 mil product..... cheaper LVP products no.

Shaw tested it with their Rigid Core so other companies would probably be good as well.

I was in your same situation. I wanted the luxury vinyl plank (LVP), but also wanted some insulating property due to the cold basement slab.

I looked into the bubble type underlayment, and the foam underlayment. I was told not to by the manufacturer (allure isocore). Reason being is these are click lock, and if you have something under them that gives, they will come unlocked, or more likely break the locking section.

The allure isocore itself is quite thick (for LVP), but doesn't really offer much insulating value. We just live with it, and put rugs where we want a little more warmth.

They do make planks designed to just "lay down" meaning they don't click lock. You could in theory put these down on an underlayment. I wonder how annoying it might be though as they would compress individually rather than as a whole so I'm sure it would be noticeable.

The manufacturer told me the only option to really insulate from the slab was to use the bubble underlayment covered by 3/4" tongue and groove subfloor or use the little DriCore panels like these. Both options add a lot of cost to the project (2x at least).

Overall I'm happy with the product. The only thing I was disappointed with is that being click lock I thought they could be unlocked. That's not the case. Once clicked you have to break them to get them apart. I was thinking they could be taken up in the event of a flooded basement.

the vinyl plank in the new house is glued directly to the slab....

My 7mm laminate floor was put down with a GOOD underlayment. The cheap underlayment allows it to move and flex and is noisy. Floor and décor recommended the underlayment. I have one bedroom with the cheap underlayment and the movement and noise (slight noise) are noticeable and the other with the good underlayment which was recommended by floor and décor. That being said, I know you're using vinul but I wouldn't want to put vinyl directly on concrete unless the manufacturer strictly forbids underlayment because with temperature changes in the slab the vinyl will shrink or expand slightly and moisture issues. Also the vinyl is so thin 1-4mm you'll have issues of transitions to other flooring in the house without an underlayment. BUT, see what the manufacturer of your vinyl flooring recommends. If it's self stick you will most likely have to go to the slab or sub floor. Floating system you generally want an underlayment so it can float (move).


Here's the underlayment I used and it's awesome.

https://www.flooranddecor.com/...4200254.html#start=3


The laminate flooring I used.
https://www.flooranddecor.com/laminate-laminate