Hi,

I am putting down a floating wood floor over cement slab. I have tested for moisture and do not have a problem there. I started to lay down the padding and started to install the first row of flooring. I started to notice
low spots in the floor. I got a 6 ft straight edge and did some testing. The floor has a lot of low spots and it seems will take a lot of work to level it.
Some of the spots are off as much as 5/8 of an inch

Here are my questions:

What is the best material to level the floor? (Tar paper? Shims?)
Should the leveling material go on top of the padding or under it?
Within what tolerance should the dips be? ( 1/8 inch? 1/16?)

thank you
Dave

Mark all spots where the straight edge tetter totters.

Break out the grinder with a diamond cup and grind them down so no more teeter totter

Check both directions all over the substrate. Now with the same straight edge, map out the low spots. Move the straight edge about 6" to a foot intervals all over the floor, and put a dot or slash where the drop off starts on both sides. Connect the dots and those are the "swimming pools" you need to screed (drag a stiff straight edge) to fill.


I'm pretty sure Ken has some info posted about this on the inter pages of www.HardwoodInstaller.com

Thanks for the info. I did look through the internet info but did not find any more info. I assume I will use a cement patch type product for the low spots, any pref on this?

I like Mapei PlaniPatch, for cost and workability. It also sets up fast so I can get more screeded out in a day, and not having to let it dry for a day before I can make my next screed next to it, if I need to.

Ardex works too, but is more costly, from my suppliers.

If I'm just skimcoating to encapsulate contaminates, it is ARDEX all the way.