I joined CSI's Specifying Practice Group webinar in progress last week, because my buddies were learning so much and tweeting about it. I got there just in time to get good answers to my burning questions about how to handle slab testing and moisture mitigating membranes and how best to pay for them.
View the story "Getting - and paying for - a problem-free slab" on Storify]
Getting - and paying for - a problem-free slab
I joined a webinar in progress because my buddies were learning so much and tweeting about it. I got there just in time to get good answers to my burning questions about how to handle slab testing and moisture mitigating membranes and how best to pay for them.
Storified by Vivian Volz · Thu, Dec 13 2012 10:19:13
Starting now! Floor Slab Moisture Problem? Join @MedcalfLouis and @dstutzman FREE webinar today http://ow.ly/fSWpH Use #CSISPG for...Eric D. Lussier
#CSISPG Vapour retarder is PARAMOUNT - ASTM E1745 (sheet) and ASTM E1643 (installation) or metal deck at elevated slabsPaul Gerber, CSC,CSI
With quality underslab vapor barriers being quite pricey, make sure that it is NOT compromised during installation. #CSISPGEric D. Lussier
#CSISPG 6 mil poly tends to "disappear" underground!! LOL @MedcalfLouisPaul Gerber, CSC,CSI
#CSISPG Turn underslab vapour retarder up at edges to keep integrety under entire SOGPaul Gerber, CSC,CSI
Why do we care so much about moisture in our slab on grade (SOG)? Moisture interferes with adhesion of flooring products, warps some, and tries to escape from under others.
#CSISPG Concrete is biggest contributor to problems - water-cement ratio, lightweight aggregates, fly ash & slag (or pozollans)...Paul Gerber, CSC,CSI
#CSISPG pH levels of concrete ad to problemsn - slab +/-12, adhesives 9-10Paul Gerber, CSC,CSI
Moisture from the concrete water itself and from rain on a slab set, and reset, the clock on concrete drying time.
HVAC normally turned on at the last possible time to save costs. Not until then is when concrete starts to dry. #CSISPGEric D. Lussier
#CSISPG Concrete drying time starts over every time the slab gets wet!!Paul Gerber, CSC,CSI
One important change in the industry is the wide availability of surface-applied mitigation products. Unlike under-slab vapor barriers, these can correct (well, really, mitigate) a problem in a slab that's already been poured.
#CSISPG Mitigation products - epoxy coatings, silicate compounds, polymer compounds, crystalline waterproofing, hydrophobic compoundsPaul Gerber, CSC,CSI
How we test is another important change in the industry. Probes that test the relative humidity (RH) are more readily available now, and it turns out they're more reliable, too. That's going to change my habit of specifying calcium chloride.
The calcium chloride test is going by the way of VOC's....out the door. #CSISPGEric D. Lussier
#CSISPG Testing is important - calcium chloride tests are being replaced by slab relative humidity tests (ASTM F2170)Paul Gerber, CSC,CSI
#CSISPG industry moving towards RH test ASTM F2170Stephanie Fargas
And here are the key reasons I will stop trusting calcium chloride tests.
Beyond "Clean the substrate" for a calcium chloride test, it is grind the substrate. #CSISPGEric D. Lussier
Skipping the "lightly grind" changes the results of the calcium chloride tests. #CSISPGEric D. Lussier
More than one time in the last year we have had "certified testing" contractors perform calcium chloride tests incorrectly. #CSISPGEric D. Lussier
So, what do we do to make sure testing gets paid for? For one thing, specify it correctly so anyone who bids on the job has to include it, or so that one agency tests for the whole project (not for each flooring product).
We have lost projects over a few hundred dollars. It is hard to carry any additional testing or preparation money on a project. #CSISPGEric D. Lussier
Or, you could forgo testing and just assume moisture barrier is required. We've done that on a couple of projects where the conditions were very likely to be problematic, like on a concrete dock over seawater.
No real set answer. I've met with designers who specify a topically applied moisture barrier under EVERY new finished floor. #CSISPGEric D. Lussier
So, how do we pay for all this uncertainty? Use a testing allowance to pay for testing and a contingency allowance to pay for moisture barriers.
#CSISPG Building in a fix to a yet unknown problem is counter-intuitive - @dstutzman feels allowance (contingency) may be best "fix" -agreedPaul Gerber, CSC,CSI
@pauldgerber You may specify testing, but whose responsibility? #CSISPGEric D. Lussier
@EricDLussier Testing is paid for by allowance by testing agent selected by Owner from Consultant's recommendation - not Contractor #CSISPGPaul Gerber, CSC,CSI
@EricDLussier @PaulDGerber Testing should be in general conditions testing section. otherwise you just have fox watching hen house #CSISPGEvan Adams
I know about allowances in theory, but I'm seldom asked to specify them because most of my projects are negotiated general contracts with guaranteed maximum prices (GMP).
#CSISPG how do GMP projects absorb unit pricing or allowances? How do owners understand? (Real-people-wise, not CSI-land.)Vivian Volz
@vivianvolz Isn't that what contingency allowances are for?? #CSISPGPaul Gerber, CSC,CSI
@PaulDGerber #CSISPG That's certainly one way of managing it... But it's not contingency if you know about it, is it?Vivian Volz
@vivianvolz It is unless you have a crystal ball that tells you exactly how much SOG moisture you're going to have! #CSISPGPaul Gerber, CSC,CSI
@PaulDGerber Kinda like the contingency on my new window project for rot repair, because I know I have minor but could have major. #CSISPGVivian Volz
@vivianvolz EXACTLY...too many factors - weather, building enclosure, HVAC operation, humidity levels, schedule delays etc etc etc #CSISPGPaul Gerber, CSC,CSI
@PaulDGerber #CSISPG So all I gotta do is get past architect's crosseyed look when I ask about contingency allowance & propose unit pricing.Vivian Volz
@vivianvolz Educate, Communicate and Collaborate!! #CSISPG...oh wait that is #CSCDCC credo!! ;) (ya'll can borrow it if ya like)Paul Gerber, CSC,CSI
So here we go! This is the Educate part... Can't wait to Collaborate and Communicate about allowances and unit prices on my next ground floor and new concrete projects!
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