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Old concrete slab moisture

#1
What do I do when I come across an slab 30 years old, with the RH readings in the upper 90's? Everyone from engineers to inspectors think they know the answer - and here's a suggestion I hadn't heard before. Apparently there's a company that will come in and drill a few holes and pump some sort of urethane between the slab and the ground to create some sort of barrier.

It sounds pretty far fetched to me - but has any one else heard of this working before?
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#2
What you are referring to has to do with sub slab grouting. If you have a slab where there is a sand layer below they do this to fill that . It has apparently been used by nyc school district to some success to bring slabs closer to ACI 302.2r06. But I do not believe it fix the problem if you lack a low perm sub slab vapor membrane.

If it were me, I'd call koester.

The grouting can also be used for slab curl issues. But that is beyond my scope.
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#3
High RH reading in an old slab, is probably indicative of a very porous slab. If there isn't standing water beneath the slab, you are probably just dealing with vapor passing through a very porous slab and giving you your high readings, and for the most part a 2-part resin material at the proper thickness can take care of your scenario. If you do have standing water beneath your slab, then you have a larger issue. That will have to be addressed, before any material can be applied, and i don't believe injecting a material beneath the slab will due an adequate enough job of dealing with physical water touching the bottom of the slab. I may be wrong, but i haven't seen that method work.

Leie Sualua - Advanced Moisture Control, Inc.
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#4
The problem with positive side sealing of the slab is verifying that every square foot of the slab is properly sealed.

I install Koster, that's what I do. It is quick and relatively inexpensive, with a full warranty that covers cost of materials and labor in the event of a failure.

Koster is the only moisture mitigation product that I know of that has been around longer than its warranty. Or should I say, has outlived its warranty, or lasted longer than its warranty.

It's a wonderful product with a wonderful group of people behind it.
JD Grafton
Concrete Answers for Flooring Problems
[email protected]
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#5
Hey CC
I completely agree with you, Koester has great product(s). I do compete against Koester and get my fair share of work as well as lose my fair share, it's the nature of the beast.

I do want make sure first and foremost that this project is a scenario that our products are fit for. I'm unaware of what conditions beneath the slab are present to warrant the need for a urethane injection material (ie, physical standing water beneath the slab). If the goal is to reduce RH levels, then we can't help, our products are not designed to reduce RH. For the most part our products may increase the RH levels as our materials act like a blanket over the slab. If the goal is to get a moisture-sensitive floor installed without concern, then that's our calling.

For the record, I push Advanced Moisture Control Products, That is what i do.
As for warranties, our goal is to ensure that everything is done properly (concrete diagnosis, concrete prep, mixing, application, verified performance) to ensure that a warranty never needs to be called on. To me that will ensure that our product is still working, even after a worst case scenario of my company folding up shop.

Regards and good luck out there,

Leie Sualua - Advanced Moisture Control, Inc.
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#6
(03-14-2011, 02:39 PM)Leie Sualua Wrote:  As for warranties, our goal is to ensure that everything is done properly (concrete diagnosis, concrete prep, mixing, application, verified performance) to ensure that a warranty never needs to be called on. To me that will ensure that our product is still working, even after a worst case scenario of my company folding up shop.

My motto also. Every job we do we do by the book, even using a timer to measure how long we mix products. It only takes a little more effort, but in the end we know it was all done by the book. I've been in this for long enough to know that warranties aren't worth the paper they're written on. Sad

JD Grafton
Concrete Answers for Flooring Problems
[email protected]
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#7
Smile 
It looks like everyone here agrees with what I thought - even the competing solution, which is no surprise. Smile
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#8
Is everyone here addressing the problem instead of offering a bandaid solution? Theres always a reason why this excessive moisture problem is occuring. Simply throwing a MPM on it isin't really helping in the long run. There can be a host of other ugly issues that will rear theer ugly heads by ignoring the main problem and covering it up.
Stephen Perrera dba
Top Floor Installation Co.
http://www.tucsonazflooring.com
http://www.floorsavior.com
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#9
Not really, excessive moisture can be caused by many things, such as a blotter layer over a perforated vapor retarder, a missing retarder, a degenerated retarder, improper retarder, fast track schedules, poor drying conditions, the list is quite lengthy.

A top end moisture mitigation system can provide a proper substrate in a matter of hours that will last the life of the building.

In fact we can now remediate concrete previously deemed unsuitable for adhesives due to contamination by hydrocarbons and fatty esters such as motor oils or food processing activities. There aren't many scenarios out there that we don't have a method to repair. A guaranteed method that is... Wink
JD Grafton
Concrete Answers for Flooring Problems
[email protected]
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#10
Ok hold on a minute, I MIGHT need a day or so to think of one.Rolleyes

Oh OK, how about AAR/ASR/ACR
Stephen Perrera dba
Top Floor Installation Co.
http://www.tucsonazflooring.com
http://www.floorsavior.com
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