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Concrete floor and laminate


Hi, I am T. Schneider with the Ardex Technical Department.

As some other participants in this conversation have mentioned, it is not appropriate to put interior-grade self-leveling and patching materials underneath a moisture mitigation system. When moisture vapors are high, the area beneath the installed moisture mitigation is permanently wet. This environment will lead to the eventual degradation of an interior-grade cement, such as Ardex K 15 or Ardex Feather Finish.

However, Ardex does offer a few exterior-grade products that can be installed underneath our moisture mitigation systems. In fact, when the substrate is too uneven to receive a uniform application of our systems (usually a CSP #6 or greater), we actually require pre-leveling or pre-smoothing. What we recommend most often for this is Ardex K 301 Exterior Self-Leveling Concrete Topping. This material does have to set for 24 hours and be shot blasted to a CSP #3 or greater prior to installing the moisture mitigation.

I also believe that someone asked why the cement itself cannot be used to mitigate moisture. Portland cements are completely breathable; they do nothing to suppress vapor emissions.

I hope this has been helpful.

-T. Schneider

For everyone's information:

Ardex Feather Finish Tech Sheet:
"This product is not a vapor barrier, and will allow free passage of moisture."

Says nothing about "degradation of an interior-grade cement".

It is important to separate our thinking here. The issue becomes the new flooring adhesives that can tolerate higher pH and moisture environments. So there are two environments:
1) Under a moisture mitigation system such as Ardex MC2, Koester VAP1-2000, Mapei EMB.
2) Under floor covering systems that are approved to tolerate higher pH and moisture environments.

It is actually covered in the passage right before what you have posted:

"This product is intended for interior use over dry substrates only. Do not use in areas of constant water exposure, or in areas exposed to permanent or intermittent substrate moisture, as this may jeopardize the performance of the underlayment and the floor covering."

-T. Schneider

What is the ardex definition of "dry substrate"?

90% 85% 80% 75%
15# 10# 5# 3#

My question pertains to the use of patching/slc's under moisture cure urethane/s and newer adhesives that block moisture and is the adhesive as well.

Wouldn't it not be just like covering it with a moisture mitigation system? Same as using MVP4 over top of the patch or slc and then gluing wood, vinyl or what have you over it?

I have gotten mixed directives from different manufacturers about this. One wants it under the mitigation systen, other want the patch/slc on top. But I have a had tome envisioning the patch or slc sticking to the mitigation system.
Stephen Perrera dba
Top Floor Installation Co.

eaadams: Our definition of a dry substrate does not have a relative humidity rating. A dry substrate is one that is not exposed to liquid water. Once you trap excess moisture vapors under a mitigation membrane, you get liquid water between the concrete and the membrane (condensation). If there is an interior-grade cement inside of that sandwich, it is going to degrade.

You would have a similar situation if you had MVER in excess of what the floor covering manufacturer recommends and you put down K 15, adhesive and floor covering with no moisture mitigation. The floor covering then becomes the "trap", immersing everything between itself and the concrete into liquid water (in this case, the cement and the adhesive). This is why we recommend moisture testing and observing the limitations of the flooring manufacturer before installing any of our products.

I hope that helps.

-T. Schneider
Ernesto: If the adhesive were being used as moisture mitigation, then no, our interior-grade products would not be approved for installation beneath them.

-T. Schneider

Now your scaring me T. lol Who can guarantee that any slab is not going to get wetter? I guess I've just been lucky all these years. I got my lucky coin with me all the time.
Stephen Perrera dba
Top Floor Installation Co.

OK Guys, I'm glad I have provided such an interesting topic for discussion but I still don't know what in the $%#@$! to do!
We are now having a calcium chloride test done (results on Friday).

Anyone have any thoughts on MAPEI Plainseal MRB, which is supposed to reduce concrete moisture vapor up to 15lbs per 1,000 sf?

Ernesto: Agreed. When in doubt, and if an impervious adhesive or floor covering will be installed, apply a moisture mitigation system, then the patch. On a bone-dry, above-grade slab, you are probably safe without the moisture mitigation step, but on an on-grade slab where the existence of an intact and functioning vapor retarder cannot be verified? I would not risk it.
morrisey: Ardex has three moisture mitigation systems that could solve your problem. 90% RH is quite manageable for us. When one of our systems is installed in accordance with our recommendations by an Ardex-trained installer, the flooring installation can be guaranteed against moisture problems for 10 or more years, depending on the system selected. If you PM me your location, I can put you in touch with your local Ardex rep who can provide more details.

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