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MMS- Are some unreliable with high RH?

(11-11-2011, 07:12 AM)Ernesto Wrote:  OK you switched from talking about after the fact high moisture readings to explicitly talking about a vapor retarder under slab. Of course if there is no retarder under slab some manufacturers will not warranty it, although the tech guy I talked to at Bostik said they warranty it up to 15 lbs.

And 90 percent of the time there are no retarders under slabs, yet you still are required to test even if there is a retarder under the slab. Why? theres a reason, go ask. Can't tell ya how many slabs are gone over without an additional layer of glue/vapor retarder. Basically MVP4 is just another layer of glue without the anti-slumping compound in it. If I am using just BB then I always step up the notch. I can read slabs. I used to strictly do sheet vinyl and never tested, never had a moisture issue.

How about their newer adhesives like the One Step, the Seal N Grip, do they function better because they have an extra layer of adhesive or is it strictly the chemical composition or both that ae supposed to prevent failures? Do they also state there must be a vapor retarder under the slab?

Now for your claim that any after the fact high reading will void any warranty. Thats complete nonsense. If that were true there would be no flooring going down and no glue sales.

The most important thing is is to NOT install when the readingsa are high.

To answer this question, manufacturer's require moisture testing before installation to verify conditions are proper for their adhesive. Remember, they also stipulate a proper and functioning sub-slab vapor retarder is required. With a vapor retarder in place and low moisture readings there should be no problems with the adhesive working for many many years.

But if there is no vapor retarder or the vapor retarder is not functioning properly (punctured, open seams, below a blotter layer) the possibility of moisture building in the slab after a flooring is installed on the slab is a very real problem. For this reason if a failure occurs, the manufacturer will test the slab and if excessive moisture is found they may very well deny any responsibility.

This happens so often when MVER testing is used and a 3lb limit is specified. A floor is installed and when the slab equilibrates or if any moisture is getting in from beneath it, the MVER climbs, alkalinity increases, and the floor fails. The moisture was always there, but a CaCl test doesn't pick it up.

JD Grafton
Concrete Answers for Flooring Problems

Messages In This Thread
RE: MMS- Are some unreliable with high RH? - CC Solutions - 11-16-2011, 11:49 AM

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