URGENT HELP!! Do you HAVE to check the moisture content of concrete installing...

[curious1234]

Our concrete slab was poured in December as our house is completely new. We are now getting engineered wood floors installed. The carpet and vinyl has been removed. I am concerned that there may be a moisture problem, but the guys who will be installing the floors told us we do not need to check the moisture content of the concrete slab. Especially since we will be using a glue with a moisture barrier incorporated into it. Do we need to push to get the moisture content checked out before we proceed?

 

[Floorist]

Yes. It takes, at a minimum, 112 days for a 4" thick concrete slab to cure. And it can take much longer. The slab needs to be moisture tested.

 

[curious1234]

Yes. It takes, at a minimum, 112 days for a 4" thick concrete slab to cure. And it can take much longer. The slab needs to be moisture tested.

Wow. So we DO need to get it tested? Even if the glue has the moisture barrier incorporated into it? We are located in the California bay area, but we are not close to any oceans...

So what are the methods used to test the moisture levels? How long does it take? Is it a simple process?

 

[Floorist]

http://www.vaportest.com/Webpages/calcium_chloride_test.htm

 

[Incognito]

I would certainly have the slab tested.

But there are "systems" that you could apply with rock solid warranty against future issues----even over "green" concrete. How much do you want to spend?

I doubt the moisture barrier/glue-in-one can handle ANY level of moisture OR that those companies that manufacture those types of products will simply PAY for a replacement wood job without documentation of the precise conditions around the time of install. In other words without a moisture test those glues aren't any kind of guarantee. So then it comes down to the installers guarantee/net worth and integrity followed by the shop owners guarantee/net worth and integrity. Do you feel lucky?

 

[Floorist]

http://www.flooringforum.com/forum/showthread.php?t=670

 

[Nick]

http://www.wagnermeters.com/video-install.php

Make sure you take photos of the readings .

 

[Ernesto]

Nick hit the sweet spot. All you have to do is ask what adhesive they plan on using. Then look up the installation requirement/pdf and most often than not....every adhesive manufacturer that I have read wants you do test the slab prior to the application of their trowel on vapor retarder/sealer.

Quite a few retailers/LIQUIDATORS/contractors out there just lay and pray. Why? Because they are either ignorant or don't want to lose the job due to expensive moisture testing. I charge minumum $350 for the first three tests per 1000sf, eithe ASTM F 2170-11 or ASTM F 1869.

Here's the deal, lots of trowel on/spray on or roll on moisture retarders have an initial limit. And if you do not test and document it then if anything goes wrong it is tough luck.

Plus, just a CaCl test wil not tell you the rh of the slab at 40% depth. Also you muct have the HVAC running two weeks prior to install sop that the interior in at living conditions. This is especially important with new slabs. On older slbas I may do it differently.

Then lets not forget about ph testing, wether or not the slab is steel troweled, power troweled, water to cement ratio and a hundred other things.

 

[curious1234]

Would something like this work?
http://www.amazon.com/dp/B00275F5O2/?tag=skimlinks_replacement-20

 

[hardsurfaceguy]

Would something like this work?
http://www.amazon.com/dp/B00275F5O2/?tag=skimlinks_replacement-20

No that won't work. That moisture meter is for wood. A concrete meter would give you indications of hot spots.or.high moisture but would not tell you what the MVE
(moisture vapor emission) rate is.

 

[domeriksf]

Our concrete slab was poured in December as our house is completely new. We are now getting engineered wood floors installed. The carpet and vinyl has been removed. I am concerned that there may be a moisture problem, but the guys who will be installing the floors told us we do not need to check the moisture content of the concrete slab. Especially since we will be using a glue with a moisture barrier incorporated into it. Do we need to push to get the moisture content checked out before we proceed?

Most definitely need to verify that the conditions of the job site meet or exceed the manufacturers minimum standards... If the slab is on grade or below.. Moisture is always a serious consideration... I would note that the length of time the slab has time to cure isn't long enough to "take it for granted" as your potential installers have indicated. Any installer who says " it doesn't need.... " " to be moisture checked" is a *flooring professional" always get a baseline reading... If not just to cover their a$$es... Simply a good moisture meter or a Calcium Chloride 24-72 hour test is needed. If moisture is elevated getting that taken care is priority one. Mold and flooring failure are prevented by simply testing off gassing of moisture from the slab first. (Not all slab installation are perfect and from the facts its always best to know. Look for a better installer.

 

[DarisMulkin]

The slab was poured in December and you are already installing flooring! The concrete takes usually 30 days per inch to cure. I would say it is got a lot of moisture in it. I'm seeing a failure in the future.

 

[C.J.]

30 days per inch to cure

I heard it was 30 days for maximum hardness (cured?). A slab can easily be cured and not have an acceptable MVER for floor covering. Two separate things.

 

[Floorist]

I always heard, 123 days for a 4" slab, just the same as Daris.

 

[C.J.]

I always heard, 123 days for a 4" slab, just the same as Daris.

Then how could it be that a 30 year old slab can have high moisture. Surely the concrete must be cured.

 

[Floorist]

Then how could it be that a 30 year old slab can have high moisture. Surely the concrete must be cured.

My dad was a concrete guy. He said it took about 50 years for a slab to dry, then it got powdery.

 

[C.J.]

My dad was a concrete guy. He said it took about 50 years for a slab to dry, then it got powdery.

Interesting. Could be something to that. I was watching something on ancient concrete and how it healed itself with new moisture getting down into its pores and reacting with the ingredients to form new bonds. Something that our concrete doesn’t do due to us using different ingredients.

I was half asleep when I was watching the video so I don’t remember all the details but that’s what I do remember

 

[havasu]

Here is what Google recommends:

How long does 4 inches of concrete take to cure?
about 28 days
Concrete is usually dry enough after 24 to 48 hours to walk on. For concrete to dry and reach its full strength, it typically takes about 28 days per inch of slab thickness. Once conditions are conducive for the concrete to cure at 85-90% relative humidity.

 

[Floorist]

Here is what Google recommends:

How long does 4 inches of concrete take to cure?
about 28 days
Concrete is usually dry enough after 24 to 48 hours to walk on. For concrete to dry and reach its full strength, it typically takes about 28 days per inch of slab thickness. Once conditions are conducive for the concrete to cure at 85-90% relative humidity.

That is 28 days per inch. 28 x 4 = 112 and that is a minimum. Still needs to be tested.

 

[havasu]

Agree. Alot has to do with whether the slab was poured on sand, over plastic, on a shady side, in the desert, below or above grade, as well.