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High Moisture Levels 1 year after slab poured, residential home
04-08-2013, 11:06 AM
Post: #2
RE: High Moisture Levels 1 year after slab poured, residential home
Ann:

Thanks for the detailed outline. It sounds like you have definitely done a very thorough analysis post failure. Here are a couple of questions I would be interested in having answered:

1) What were the pre installation RH and/or calcium chloride numbers?
2) What were the ambient conditions of the environment when the above mentioned tests were completed?
3) What is the nominal thickness of the slab?

That being questioned, her are a few things, based on the information and timeline that you have provided, I would like to bring up:

1) Rule of thumb for drying (not curing) of a slab: it takes approximately 30 days for every inch of slab thickness, once the environment is conducive for drying i.e. window and doors in, HVAC up and going, for a slab to reach an RH% level in the 80's. Your floor was installed four months after slab placement. Was it dry enough at the time?
2) Most wood flooring products will require 75% RH or 3lbs CC readings to be acceptable for installation.
3) You very easily could dry out the top surface of the concrete and get acceptable CC readings for reinstallation. That being said, the RH levels very well could still be in excess. Be cautious when trying to expedite drying.

Here is one question I would like you to think about:

a) Do you want to know what the moisture condition at the surface of the slab is right now or
b) Do you want to know what the moisture condition at the surface of the slab WILL be once you have your floor installed?

Proper RH% testing answers b. Calcium chloride does a.

Last thing would be solutions, based on where your RH% numbers are currently. They do make moisture remediation products specifically designed to encapsulate less than desirable levels of moisture, prior to installing moisture sensitive flooring products. Many of them are two part epoxies.

I hope this helps. Please don't hesitate to let me know if you have any further questions.

Jason Spangler
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RE: High Moisture Levels 1 year after slab poured, residential home - rapidrhrep - 04-08-2013 11:06 AM