Hi,

My wife and I want to install Smartcore Ultra luxury vinyl flooring in our basement, which we are working on. We are sold on a lot of its qualities, but we have come across mention on the Internet that our floor needs to be level within about 3/16 of an inch before we install it.

We have not checked our floor with a proper level to make the calculations. But our question is this: IF our floor is, say, 1/2 an inch not level overall (or more not-level than what the experts say is permissible), sloping slightly to one end, then what exactly is the big problem with us installing the Smartcore flooring over the existing floor anyway? The Lowe's guy we talked to said that for one, the installers wouldn't install until the floor was level. But assume for now that: (1) WE want to install ourselves; (2) there are no dips and valleys, just a slightest slope from one end to the other; (3) we want to avoid leveling our basement floor, b/c cost and time; AND (4) that cosmetically, we are pretty much AOK just taking our existing basement floor and making it into a Smartcore floor but otherwise as-is.

What exactly is the risk/potential damage of doing so? Will the planks break? Will they not connect? Will any structural issues be caused that would not be there on a perfectly level floor?

Thanks for any and all advice and insight!

The guy at the store is confused about any requirement that your floor be level. The requirement is that it be flat to within a certain tolerance. If you get water spills, look to mop it up at the low end of the room, that's all. You won't notice a small slope when you walk around. A bump or low spot you may scuff or notice deflection with weight applied.
A layer of roll roofing or single three tab shingle will be about an eighth inch, so it makes the smoothing process easy since you can be within an eighth inch depending on how many layers need to be closest to "flat".

Thanks, man.

We will conduct proper level test with proper mercury level. But in the meantime my hunch says that we should be able to work with what is as-is.

Your "roll roofing" or "single three tab shingle" idea -- is that an alternative to self-leveling concrete, for folks who want to level out the floor a little more before laying down LVP? And is this stuff easily found on the internet/home improvement stores?

Using a straight-edge you will be able to mark low spots in a "contour map" design where you would need to elevate the area with a single or multiple layers of tar paper.
You may also use 30 pound tar paper for a tapering effect. For a wood floor I use 3/8 inch staples to hold the paper. Use sticky masking tape or duct tape so everything doesn't slide around before you cover with 6 mil plastic sheeting, or special underlayment foam.

Thanks. I will try that out.

Level and flat - big difference!!! People who talk about level don't know what they are talking about. Substrates just need to be flat in a 3/16ths inch in a 10 ft radius. Or 1/8 inch in a 6 ft radius.

Have you considered leveling your floor with a concrete floor? That would eliminate the problem.

It's better not to take the risk and make self-defeating concrete.