Pre-Finished or Finished On Site

[wcheaib]

So question: What is the accepted product to use to measure moisture in concrete - is it the calcium chloride test?

 

[Ernesto]

According to the ASTM people the only valid test for moisture in concrete is the ASTM F-2170 as the findings on CaCl has no pedigree. However some manufacturers allow CaCl. Do what the man says.Then you have the glue manufacturer who may say different and or say no test needed. But then the glue people say follow the flooring manufacturers installation guidelines. hahaha fun huh?

 

[highup]

Here's the response from Tech Support from General Tools, the manufacturer of the General Moisture Meter.

The MMD7NP is not calibrated for concrete. The Masonry mode on this model is only for traditional masonry such as brick, mortar, plaster, and tile. Due to the make up of concrete, the MMD7NP will always register false high moisture on that material.

So my hardwood installer was using the wrong meter to measure moisture (wtf).

I was confused when I read their (General) specs because it said "masonry" not concrete.

 

[wcheaib]

I have attached the results of my calcium chloride test. We sampled 6 different locations over 66 hours. The weight gain results ranged from 1.7 to 2.2 grams.

1. Dining Room - 2.2 grams
2. Kitchen - 1.8 grams
3. Bedroom East - 1.7 grams
4. Bedroom West - 1.8 grams
5. Gym North - 1.9 grams
6. Gym South - 2.0 grams

My GC is telling me that the threshold should not exceed 3 lbs / 1,000 sf / 24 hrs. If you do the calculation, it looks like I'm either at the threshold or slightly above it. In other words, I have a moisture problem.

 

[highup]

Great you had the test done. It gives you something more definitive, rather than guessing because it looks dry.
The GC is correct. I'm not sure what I would do if I was in your situation. Maybe a moisture limiting adhesive would work. Maybe........ That's the hard part.
Did you have the house built? Just curious if special grading and barriers or sealers were applied to the exterior concrete below grade.

 

[wcheaib]

No I bought the house 4 years ago and added a basement extension totaling 800 sf. The foundation walls are wrapped with a water/moisture barrier - that's code in Toronto. For my existing, the walls were first tarred and then wrapped with a Delta waterproofing membrane. For my addition, we used a Rub-R-Wall spray applied waterproofing membrane followed by a Geo-Wrap composite drainage and protection membrane.

 

[highup]

Just out of curiosity, wondering if the sump pump in the addition is coming on any less often as time goes by.
I do like the way the house is protected on the exterior below grade. If that's code, I'd bet the area under the slab is well prepared too knowing that a sump pump was part of the package. The numbers are dryer than I would have guessed.

If the two part method is better but more expensive, is that something you could do? I can't imagine it being any more difficult that troweling it on and back rolling it as you go.

 

[Ernesto]

I'd do a 2 part epoxy moisture blocker like Sika makes. Then perform more CaCl tests before committing to gluing wood down.

 

[highup]

I was party to an installation with the UZIN products. The epoxy was very impressive. It as far as I know is designed for use under their levelers. I'm not sure if it's also possible to use the product as a moisture barrier for wood flooring adhesives. It would be worth calling them to see if it will work that way. Whatever system, I'd use all products (moisture barrier and adhesive) from the same company.
https://www.uzin.com/service/contact-worldwide/

http://www.uzin.us/products/product-search/details/uzin-pe-460-moisture-vapor-retarder-13135/