|Stephen Perrera |
Moisture Emissions Over Top Of Bostick MVP4
Been working on a job for five weeks. lol
Lots of solid wood over concrete with a floating 3/4 ply subfloor over Bostik MVP4 and plastic.
Has anyone else done CaCl tests on top of MVP4 before? How about doing a CaCl test over top of MVP4 and 6 mil plastic?
Well I did. The test results are amazing. I also ran Wagner Rapid Rh tests before the MVP4 application and checked them two weeks later. Now this is what I call fun.
Last Edited 3/8/2011
|Stephen Perrera |
It appears that ASTM does not want or suggest emission testing over the top of patches, SLC's and coatings. Meaning...they want it so you have to take the word of the manufacturer of the moisture retarder that their product will preform to their specs.
Hmmm, just wondering if the moisture mitigation industy pushed that part through.
Seeing that the industry is headed towards exclusively performing rh insitu testing..... emissions out the top of concrete slabs do not seem to be a primary concern anymore.
So, when your doing a F-2170 test and it is borderline rh% they are telling you what as far as potential emissions are concerned? That the flooring will be fine, just enough?
If your using a trowel on vapor retarder and the manufacturer states it reduces emission rrates from 10lbs in 24hrs per 1000sf down to 3lbs...does it matter if you test afterwards? Will they stand behind their product and pay for everything? Is 3lbs safe? Same with a 75% rh in the slab, is that safe or not safe? Sensor drift can be + or - 2%
IMHO it's the emissions rate and alkaliinity, and the relative humidity content of the slab thats going to bite you. Why has no one found a correlation emission rates to rh% in a slab? No one denys it is the emission rate that effects flooring and produces higher alkalinity.
They say, emission rates have no correlation to rh and vice versa. But the question arises; Then why do the manufacturers of many topical trowel on retarders and coatings specify the 3lbs/24hrs/1000sf in their literature?
Who are you going to believe and what testing will you do to protect yourself?
It appears this topic has sparked a lot of discussion over on Linkedin forums. Many experts refer to the ASTM E96 method as to how these films are tested for accuracy. This is how they determine the vapor movement through the specimen.
So a friend of mine called and was also just as confused. Lets call him Carl. Carl did a little research and found that one of the ways the coatings/films are tested is in fact the dessicant method. The dessicant is.....thats right, Calcium Chloride.
Read what Carl sent me below and you make up you own mind. Should you stick with one method of moisture test or do both the ASTM F 1869 and the ASTM F 2170.
From Scope 1.1 as I read it. "Two basic methods, the Desiccant Method and the Water Method, are provided for the measurement of permeance, and two variations include service conditions with one side wetted and service conditions with low humidity on one side and high humidity on the other."
However later in Section 4 it states:
4. Summary of Test Methods
4.1 In the Desiccant Method the test specimen is sealed to the open mouth of a test dish containing a desiccant, and the assembly placed in a controlled atmosphere. Periodic weighings determine the rate of water vapor movement through the specimen into the desiccant.
4.2 In the Water Method, the dish contains distilled water, and the weighings determine the rate of vapor movement through the specimen from the water to the controlled atmosphere.
The vapor pressure difference is nominally the same in oth methods except in the variation, with extremes of humidity on opposite sides.
Kind of confusing isn't it?
I never really paid much attention to this standard because I usually state that it is not applicable for flooring. This has opened my eyes a little more
Last Edited 10/30/2011
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