We have a single story, 375,000 square foot facility built in stages between 1963-1970 in Southeast Fl. Most of the building is dock high and has a 4" slab with a vapor barrier. In the past few years we have had a problem in various areas, not contiguous, with mastic holding under VCT, carpet tiles with rubber backing, and gym rubber floor and mats. We even had some growth under VCT in one area. [/size] I have done RH tests-95-99% and calcium chloride tests- 14-19lbs. We have checked roof drains, GPR, the water is overhear and there are no obvious areas of water intrusion or leaks. Any thoughts?
01-12-2014, 10:57 AM
(This post was last modified: 01-12-2014, 11:01 AM by Ernesto.)
The barrier has been compromised; ie damaged or has disintigrated is my guess. Hard to say whats gone on over the years. Also when a new section of slab was added it may have not been sealed up tight.
When you say the roof drains are checked do you mean a camera was sent down them and the path of the line and condition was checked? Also besides the larger lines there may be 2" lines that connect under the slab and they should be checked. That age could have cast iron with the bottom of the pipe rotted out.
It's very likely the vapor barrier has been compromised through deterioration. To verify, cut a section of floor out where the failures have occurred and check the condition of the vapor barrier. Depending on the aggressiveness of the soils, it is not uncommon that is 6 mill vapor barrier can deteriorate within 10 years.
01-28-2014, 10:39 AM
(This post was last modified: 01-28-2014, 11:02 AM by eaadams.)
If your building is 35-40 years old the odds of there being a vapor barrier under the concrete is low & highly unlikely. The odds of it being 6-mil are high. I do not know of any 6-mil that works (even today) as a vapor barrier. At best it is a retarder. 6-mil is what you buy at the local big box for residential work. It isn't ok for commercial work.
I get a LOT of warehouses in the SF Bay Area that are 'dock high' that get converted to normal use buildings. They always have moisture issues, none of them have vapor barriers, and they always have to be sealed.
Anyway, if you have 6-mil you deff don't have anything below the slab if the RH & CaCl are high. The slab needs to be sealed with an epoxy system.
Watch jason's video on Hydrostatic Pressure on youtube. You need not worry about 'water intrusion' if you dont have a water head above that dock level. You probably have ground moisture coming up and causing the issues.
Also it sounds like you are an educational / sport customer. If you want PM me some details and I can hook you up with someone in FL who can help you get this done properly.
I have a similar problem with a 17 year old slab on grade house. It's on heavy clay soil (the subdivision used to be a cypress dome) in central FL. Calcium chloride tests range from 5 - 17.2 lbs.
I've had a couple of companies come out to give estimates on under slab sealing. They pump chemical grout through small holes in the slab (on a 3ft grid) to seal under the slab. Several companies in FL do this, but I have not been able to find much info about results.
Has anyone see this done, either in residential or commercial applications? Was it successful? Did the flooring have to be removed to allow the slab to dry once it was sealed? Any info on this procedure is appreciated!
Under slab pumping is used to stabalize a foundation. It has nothing to do with concrete moisture and flooring. Who ever is telling you that doesn't get it. It might be an issue you have but it won't fix concrete moisture issues.
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And after they pump all that WET grout under the slab it'll never dry out. The grout is extra wet for pumping I believe. Now if they could pump some plastic under it....
No they use an epoxy laiden grout.