Hi Everyone.

What a great forum! I have been lurking here for weeks learning a lot by reading through dozens of posts as we get ready to install our new hardwood floor.

I have a question about moisture barrier.

We're on a concrete slab foundation about halfway up a hill. A previous engineered bamboo floor cupped and warped very badly, and we later learned it was because the guy who installed it didn't put any moisture barrier down first.

So that got ripped out. Then there were some pipe leaks in the slab, itself. The previous owner repiped and ran PEX through his attic. So there's no longer any pressurized water of any kind running through the slab.

We bought the house and are looking at putting in an engineered wood. I've been told by the installer that a coating of Deco-Rez will stop any moisture problems we may have, but just to be sure, I went out and bought a Calcium Chloride moisture test kit and ran it on three different areas of exposed concrete.

According to the National Wood Flooring Association (http://bit.ly/1cejw0c), CaCl test results should be interpreted this way:

1 - 3 lbs: direct glue-down is OK
3 - 7 lbs: need to lay down a moisture barrier first
7+ lbs: might not be able to have wood flooring

(see the bottom of page 11)

Here were my results from the three areas I tested:

Location 1: 5.4 lbs
Location 2: 6.0 lbs
Location 3*: 1.75 lbs

I put an asterisk by Location 3 because that area was just treated with Deco-Rez a week ago, and I was curious to see how much moisture it let through.

My question is: should I be worried about the moisture content of the other untreated locations? We are going to put down Deco-Rez throughout the entire slab before putting down the engineered hardwood floor, so I expect those levels to go down, but the 6.0 lbs reading at location 2 spooks me a little.

Do you think we're going to be OK putting engineered wood on Deco on this floor? I tried to find out moisture tolerances for the hardwood I like online, but couldn't find anything.

Here's the floor we're thinking of putting down:



Appreciate any advice you might have.

Thanks!

Personally I think that tells me what you should be focusing on and I'm glad you included it. Even the best insurance will not stop moisture from absorbing into the slab especially if it's forced...gravity...water runoff. Unless of course, if you had a gasket around the whole slab that diverted it. Though that's not possible, insuring proper runoff is a big head start to avoiding problems.

Those are my thoughts.

Hi Ken.

Thanks for your comment. What's odd is that none of my neighbors seem to have any particular issue with moisture creeping up from their concrete slabs. I'm going to conduct the CaCl test again once the Deco-Rez has been applied in the first two test areas.

According to LM Flooring, the manufacturer of the engineered wood floor we're considering, slab moisture levels should be less than 3 lb/1000 sq ft/24 hrs to ensure there will not be any problems. (http://bit.ly/17Fp981)

I am planning to install French drains all around the house to keep moisture away from the concrete foundation. Geo-soil moisture analysis shows that we don't necessarily have a high level of moisture in the soil, but there is a bit close to the surface. Hopefully the drains will siphon that off and send it to the street.

The only thing I can throw out there is that most adhesive manufactures want you to use "their" sealer as part of a "system". Using one manufactures sealer and another adhesive could lead to pointing fingers later on down the road if a problem does arise.

Yea I agree with Kevin you should probably look at a system from one manufacture.
Another suggestion would be to do a core drill to make sure the slab has a moisture barrier installed underneath it. No matter what you apply to the top if there is no plastic under the slab it will do no good. The international concrete repair institute says this should be preformed before any moisture tests are taken.
Also I would suggest doing rh testing as they are more accurate, and are becoming the more preferred method by companies. If you have any sealer on your concrete then that would throw off your CC test. (that could even be a curing agent the concrete finishing company applied) If you ground the concrete then you have to let it set for 24 hours before administering the test, the list goes on and on for accurate C C testing. Rh is more accurate and they can be left in so you can always come back and see what the tests read if you ever have a problem.

Hi Guys.

Thanks for the advice! Just want to clarify one thing. This is the moisture barrier my installer is using. Anyone know how this might compare to Bostik MVP? It's hard to find independent rating systems on the Web which let you compare one barrier to another.



Thanks again!

For those who may be interested, I decided upon a different moisture barrier: WAKOL PU 280. The manufacturer guarantees its effectiveness in writing, and two coats will protect up to 18 lbs/1000 ft/24 hrs.

Jeff Meltzer at Universal Hardwood in LA recommended it, and we're going to put it down soon.

Overkill? Probably. But if you had to deal with the aftermath of moisture problems with hardwood floors, you'll know it's well worth it.

Thanks again to everyone for their suggestions!

Small update:

We're going to use DriTac MCS 7000 moisture barrier. They have a written guarantee that their product will block up to 12 lbs of moisture when used with their glue.

Curious to know if anyone has experience with this product.

Hi Guys.

Just wanted to let you know that my new hardwood floors are installed. Check them out:



We went with engineered hickory from California Classics, and used the moisture barrier I mentioned in my last post. Should protect up to 12 lbs/1000 ft/24 hours. (My highest moisture reading was never more than 6 lbs.)

Hopefully this means we will never need to see those concrete slabs again!

Thanks for your advice, guys. Really made a difference.

Sagar