I am still concerned about possible moisture damage even though my contractor is not.

He is installing an enginnered 3 ply by 1/2 inch by 5 inch plank directly to my ongrade concrete slab with bostics best.

Does Bostics best also work as a moisture retarder? Or should I insist on him using MVP or vinyl in addition.

"I live in a townhouse and the sprinker system wets one wall."

I mean even enginneered has it's moisture limits right?

Thanks

Well, for him to be so sure ask him to test the concrete along that wall with the sprinkler, with his Tramex Concrete moisture encounter, to see if it has an indicator, if he even owns one(he better own one, if installing over concrete) If he has already checked it, then he should have no problem showing you. I show all my clients so they witness it. I also take photographs of my readings.


He may have taken readings and knows the concrete is "dry"


Bostiks Best is not a moisture barrier or moisture blocker.


Who's buying the MVP? As a contractor, I pass all cost of the materials used on the job, to the client. What exactly does your contract state??? I hope it is a very specific contract so no confusion about what is what.

I get the impression full spread moisture barriers aren't being used that often.

http://www.hardwoodinstaller.com/hardwo ... =9855#9855

Nope, I have only had to do it once, after checking the concrete for indicators, and it wasn't MVP. It was Taylor roll on.

My question is what is the LIMIT of moisture.
I have a wood subfloor and a concrete subfloor. I want to put engineered on top of both.

It is I that am insisting on contractors using the moisture readers as most contractors here never use them hense my year long search for a decent one.

My question is again-If my wood subfloor measures 10% do I need a moisture barrier or can I just use bostics glue alone and an engineered and be done with it?

What is the limit on the concrete? Slabs change year round. The last joker did not have a tramex. He just said it looked dry and I said bullshit. You must measure.

With wood subfloors, between 10 to 12% is fine. Many manufacturers specify a 8 mil poly vapor barrier installed on the earth under the house when there is a crawl space. NOFMA and the NWFA specify this as well. It isn't as critical with an engineered to have the vapor barrier but if the space gets very wet, it could cause problems with the flooring. On a slab, the GENERAL guidelines are 3 to 3.5 lbs. per 1000 sq.ft. in a 24 hour period. I don't use a Tramex moisture encounter and instead, rely on a calcium cloride test. Both are acceptable for reading moisture in a slab. But keep in mind; the reading is a "snapshot" in time. The slab could read higher at a different time of year. MVP or other moisture barrier systems are like an insurance policy. Good to have when you need them.

Thanks Gary for a clear and consise answer!