Part of the issue is a drain needs to have 1/4" slkope per foot. Vinyl plans need the floor to be flat to within an 1/8" over 10'. You will end up with broken snap-locks and have zero warranty. What about a mositure barrier or you will end up with mold, not if, when.

Manufacturer said no moister barrier needed

I agree this is not going to function in a flood anyway unless you have the proper slope and for sure not possible with click lock flooring .

I definitely don’t see us hosing down the basement floor. Thought the manufacturer said no barrier needed, I think we will lay one down anyway. Thank you both for the input

The no moisture barrier thing just moves the mold from underneath the moisture barrier to underneath the floors themselves. No vinyl but gluedown works with a sloped floor and floor drain. This is an expensive failure going to happen here. Vinyl gets ruined from too much moisture and moisture vapor. The marketing is a lie.

" Manufacturer said no moister barrier needed "

Is that in writing, because I would doubt it? It is on a concrete slab. From my perspective it MUST have a moisture barrier of some type. Moisture form below is the main issue and every slab has moisture, no matter what. That coupled with the flat that the floor needs to be pitched towards the drain tells me you will have a mess on your hands in short order.

It’s pitched toward drain, but we are going to bypass what manufacturer stated and put barrier down. What mil would be good?

You cannot pitch snap together flooring is what we are trying to tell you and I agree always some kind of moisture barrier in a basement floor . The only way to handle thta slope is glue down flooring

This is what I posted earlier and the fact that you really cannot use this product on a pitched slab. More red flags than just the moisture barrier

" Vinyl planks need the floor to be flat to within an 1/8" over 10'. You will end up with broken snap-locks and have zero warranty. "

@Bev a 6 mil plastic vapor barrier will be fine. Use a plank to create a "door" to access the drain. it will need to be glued in place and pried up if you need access to it but you wouldn't have to unlock the entire floor. As mentioned above, if your slope is steeper than 1/8" over the length of 10' you will probably have issues with the joints opening. I prefer a glued down LVP for this type of project but you already have the LVP so you might be stuck with it. A glue down plank goes with the slope and doesn't have issues with unlocking since it's glued down.

Update:

Hopefully you dont need to ever use it. Our drain is in the mechanical room is read of a living space and no LVP in there. We have had several, yep I typed that, floods in our basement and the flooring has held up every time. We’ve had restoration in and they do moisture readings and it’s survived within what they think is okay. Drywall and baseboards not so much!

Good to know that about floor. Hope you got drain problems solved for the future., we haven’t had any leaks.

Yes one was caused by our builder and they paid for everything and it was two weeks after we moved in. Huge nightmare. But all done correctly. 2/3 were our fault and running water in the bathroom. Oops.