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Concrete floor and laminate
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03-21-2011, 08:03 AM #1
morrisey Newbie *
Status: Offline Posts:5 Threads:1 Joined:Mar 2011
The Reader's Digest version of our saga is that 4 years ago we had laminate flooring installed (over previously carpeted/tiled areas) in 75% of our home (built in 1987)--. The laminate began to bubble at many of the seams. After a protracted time of dealing with one of the national home improvement chains, they agreed to replace the laminate. When they began pulling up the old laminate --black mold everywhere. We've now been out of our home for 2+ weeks while it goes through mold remediation. It appears that there were 2 possible causes of the problem-- the underlayment was improperly installed and we have a "wet slab" (90%+ rh). The area that had previously been tiled had no mold whatsoever
The question -- we still want to re-install laminate. Will a sealer, such as MVP and a higher grade, properly installed underlayment solve our problem or are we doomed to tile and carpet??

03-21-2011, 01:19 PM #2
CC Solutions Concrete Moisture Evangelist *******
Status: Offline Posts:1,067 Threads:69 Joined:Dec 2009
The short answer: A mitigation sealer can resolve the moisture issue.

The problem: You should find out why you have the issue first. If you have a poor or no vapor retarder, you are going to get moisture movement up through your concrete slab. This moisture can be stopped using a high performance mitigation system, or slowed by using a less effective moisture blocking system.

Some systems protect to a certain level of moisture emission, say 8lbs of MVER or 80% RH. When you put these systems down, you are hoping the moisture level in the concrete slab never exceeds the threshold of the moisture system. If it does, the system may fail and you will be right back where you started except you will be that much poorer and wiser. Sad

Other systems protect to an unlimited moisture and alkalinity level. These obviously will be more costly.

If you find your slab has a working and effective vapor retarder and there is no chance that the slab will get any additional moisture gain, it may be feasible to use a less expensive mitigation product that provides some level of moisture blocking. If however your slab has had 20+ years to dry out and still causes flooring to fail and mold to form, chances are good that the moisture problem is much larger than just excess mix water needing time to dissipate.

In your case I would recommend against a limited system such as MVP and suggest a moisture mitigation system designed and warranted to unlimited alkalinity and vapor transmission.

You will be told by many that this or that product will work just fine, and you will be shown warrantees and guarantees and dozens of happy clients, but you must think about what the cost of failure is, considering mold and having to leave your house, let alone the failure and replacement. The truth of the matter is, if moisture is getting into the slab and you put something on top of the slab that seals it (being wood, vinyl flooring, or even a mitigation system) the moisture level will start to go up over time. At some point the moisture and alkalinity will defeat 99% of the systems out there.

If I were you, I first look for the cause of the failure, and then either install a bulletproof mitigation system or go back to a breathable floor covering.

JD Grafton
Concrete Answers for Flooring Problems

03-21-2011, 01:29 PM #3
morrisey Newbie *
Status: Offline Posts:5 Threads:1 Joined:Mar 2011
Thank you for your response, however, I sure was disappointed in the answerSad.

According to the leak detection company, they often see these rh%s in our area (central florida)
You had mentioned systems that protect to an unlimited moisture and alkalinity level as I am new to this (and wish I never had any need to know any of this), where would I look for such systems?

03-21-2011, 04:34 PM #4
Ernesto Concrete Moisture Expert *****
Status: Offline Posts:606 Threads:33 Joined:Sep 2009
Have to agree with CC for once. Big Grin

I'd like to add that those 2 n 1 or 3 n 1 vapor retarders the big boxes sell only work up to 5 lbs measured with a calcium chloride test. These are easily overwhelmed by wetter than normal slabs. I used to see it alot out here when I did inspections.

First off check the grading around the house. Make sure you have rain gutters and rain water is deverted away from the house. Use french drains if needed as well.

Also when you say 90% rh, how was this number derived, like what test? Was it a concrete meter test, a relative humidity test or what?

If you pull up a floor thats been covered and immediately throw down a concrete meter your always going to read high.

I have found that a good trowel on vapor retarder like Bostik MVP4 (cured) and then 6 mil plastic with the 2 or 3 n 1 cushion is virtually vapor proof. Cool

On one I even undercut the sheetrock ran the six mil up the wall 2 inches, vented the baseboard so if any emissions were to get around the plastic and cushion it would not go into the wall or sheetrock.

Stephen Perrera dba
Top Floor Installation Co.

03-21-2011, 05:03 PM #5
CC Solutions Concrete Moisture Evangelist *******
Status: Offline Posts:1,067 Threads:69 Joined:Dec 2009
Stephen may be a better resource than I on this issue as I only work on commercial projects.

I don't know if I should get into product preferences here, but there are only three bulletproof systems I know of. These share similarities such as being two part epoxy systems that requires bead blasting the concrete and grinding all edges and corners where the blaster can't reach. The epoxy is applied to a specific thickness and the floor is then ready for further finishing.

Costs will be less than the price of failure. I do my work at $2.50 a sq/ft and up, with complete systems including self-leveling underlayment usually running around $5 sq/ft. Small jobs cost more, I charge $8 /sf if the job is under 1000 sf. The price of the epoxy alone will be about $2/sf for your application.

Again, rejoice that the problem is resolvable, but I must caution you that there are so many snake-oil salesmen out there you must be skeptical of all promises. Wink

JD Grafton
Concrete Answers for Flooring Problems

03-21-2011, 08:57 PM #6
eaadams Concrete Moisture Expert *****
Status: Offline Posts:600 Threads:88 Joined:Jul 2010
Also, the supposition of doomed to tile or carpet is wrong. This could be a localized problem and putting tile or carpet could also fail. Further, there is next to zero chance that carpet will not mold. People think carpet will breathe but that doesn't guarantee any sort of mold safety. You had better check all drywall for mold now also.

The prior statements on vapor systems are correct. There are only a few good ones out there.

03-22-2011, 03:40 AM #7
morrisey Newbie *
Status: Offline Posts:5 Threads:1 Joined:Mar 2011
We had carpet down for 15+ years and when it was removed there was no mold or wetness. Also, where we previously had tile in the foyer and we replaced that with laminate, when they took up the laminate there was NO mold where the tile had previously been. Sealer used for the tile?

The moisture test was performed by a leak detection company. This test was performed a day or two after the old laminate had been removed. They drilled into the slab and inserted a probe, which they removed 3 days later. The results we were given were for rh.

Received "official" word yesterday that the national home improvement company that installed the original laminate refuses to re-install flooring for us. They no longer want any liability. I just want floors that will last a while.

03-22-2011, 05:53 AM #8
CC Solutions Concrete Moisture Evangelist *******
Status: Offline Posts:1,067 Threads:69 Joined:Dec 2009
You may find that most flooring installers will shy away from this problem. You can see why! It is costly and if mold affects a resident the costs can skyrocket.

JD Grafton
Concrete Answers for Flooring Problems

03-22-2011, 06:01 AM #9
morrisey Newbie *
Status: Offline Posts:5 Threads:1 Joined:Mar 2011
I can somewhat understand but where does this leave the homeowner who must rely on the expertise of companies who are in the flooring business to determine the proper product and application methodology? If they don't have the expertise how in the world is the homeowner supposed to know what is right?!?!?! I don't know where to turn.

03-22-2011, 06:17 AM #10
CC Solutions Concrete Moisture Evangelist *******
Status: Offline Posts:1,067 Threads:69 Joined:Dec 2009
It's not much different than the car mechanic problem we all face. Who can you trust? And once you find someone, stick with them!

With moisture the problem often shows up long after the flooring installer is gone. Some installers have been in the business 30 or 40 years and haven't seen these types of problems before the advent of low VOC adhesives. Some are in denial and blame unrelated circumstances, the owner, or voodoo.

You are way ahead of the game now because you know you have moisture below your slab. You know you must treat it. Now all you need is a system and an applicator.

JD Grafton
Concrete Answers for Flooring Problems

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