When the slab got wet before the framing was done, there were wet spots, but no big puddles, except one which is in the carpeted area. It does look good to the naked eye. I will ask them to check the floor like you suggest. Thanks!

Make sure they check the areas you suspect to be unlevel. No concrete slab is perfectly level, but they should be close.

Read through the bottom of my thread where I talk about how my slab was out of level and how it's cost me time and money. Have them check with a laser level that the floor is level before they proceed further. My slab was over 1" in 10' out of level.

You can get a cheap (but accurate) laser level at Home Depot that will project a solid horizontal line over 180 degrees. You can run around and put a tape measure and measure down from the line. (This device will come in handy later for hanging pictures, checking for plumb and level in other areas, etc) It's a fast and easy way to validate a floor.

Or - you could roll a ball or some marbles around the floor (esp those lost ones) to see where they end up. But the laser level will be something easier to quantify for your builder.

Is there a reason you need it to be perfectly level? As long as it's flat, slightly out of level shouldn't matter.

Thanks,all. I have asked them to verify with a laser that there are no variances in the slab. Hopefully, it will all be within an acceptable allowance and they can finish the job! There was one big dip, if I recall, but it was in an area that will be getting carpet.

FYI: My engineered hardwood was put on a slab without glue and with a membrane or waterproof cushioned layer.. I really like it like this and feels more like a raised house and install costs less.

I went through this in a basement reno with laminate flooring. Level does not matter for flooring. FLAT matters. Mine was crazy unlevel and moderately unflat. Flatness is checked with long metal level, and other techniques such as marbles and tinted water.

There are many techniques to help flatten a slab: Grinding, SLC, trowel on mixes. If you are prepping for a glue-down install, then take great care.

If you are aiming for level and flat, include the laser.

Level does not matter for flooring.

It certainly does if it's off by more than 1/4" in 10'. Try putting furniture on a floor that slopes from one side to the other, or try putting cabinets in. Ask me how I know.

Hi cp, you're saying it matters for things other than flooring. That's a diff story.

A laser will tell you the fall, if any. It won’t do a good job of identifying humps and bumps and birdbaths.You need a long straight edge for that. Humps get ground. Birdbaths get filled. It’s a two prong approach to do it correctly.

And it’s still a big risk to place wood of any kind below grade.

Try rolling marbles across the floor.

Hi cp, you're saying it matters for things other than flooring. That's a diff story.

No it matters because the floor is not level! PERIOD.

if it's off by more than 1/4" in 10'. Try putting furniture on a floor that slopes from one side to the other, or try putting cabinets in.

I really don't want to ruffle feathers, but a 0.5° slope is typically not detectable without visual clues, so there is no way that a 0.12° slope is. I suspect that most U.S. houses are not built within that tolerance.

Some will tell you that 1" over 12' is fine, certainly 1/2" over 12' is fine, in the end, whatever feels fine (comfortable) to you is the right answer. Now flat is a whole different story, and can be a bit more important.

I routinely design installations with floors well over 1" out of true in 12'. I've had 1" in 6' happen. That's the reality of old houses! There are ways of doing this that do not impact the overall look. Designing the toe with extra room to be scribed to the floor is one way that works if you are creating a custom installation that features design details at the floor level. It does require extra skill from the installer, as it all rests on his shoulders to make happen properly. It's the same for the crown. If there is some sag in the ceiling, using a multi part crown, and planning for some drywall mud as well will disguise it to the human eye.

This room is off 1 1/2" from one side of the kitchen to the other. Because the wall cabinets are in 3 separate sections, and the molding is a 4 part crown, and we fudged the backsplash spacing a bit, we were able to disguise it to 98% of the people that see the install. Without using custom cabinets, the only way to disguise the base cabinet issue was shoe molding, and a custom cut toekick to hide the shimming. If this were a custom cabinet line, that would not have been needed as m custom cabinet maker could have scribed everything to fit and then made custom toe details.

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I routinely design installations with floors well over 1" out of true in 12'. I've had 1" in 6' happen. That's the reality of old houses!

Agreed that in an old house it happens but in a new build the tolerance should be closer to 1/4" in 10'.

The OP said:

We are in the flooring phase of our new build.

Meaning it's a new build and should be level! Just like it should have been level on my brand new slab in my brand new construction house.

Again, a slope 1/4" in 10' isn't detectable by humans, so why bother to get your house engineered to such exact specifications? When you get beyond the ability of human perception, I think it is time to just say, good enough.

The OP has the basement and is asking about a self-leveler. The answer to that question is really personal preference. If it bothers you, then fix the slope. If it doesn't bother you, then don't fix the slope. If you need to fix the slope and the home is brand new, talk to the builder and see what he says.

Turns out the floor was pretty flat and didn't need anything in the areas that they put hardwood on. We will check the carpeted areas before that goes down.

The foundation company does a great job on the slab, that's one of the reasons they were hired according to the GC. They checked it though, so thanks for all of the great feedback.