Moisture issues in concrete slabs

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Author Message (Unregistered Guest) Unregistered guest Posted on Saturday, November 13, 2010 - 09:42 am:    What is everyone doing to mitigate moisture issues in concrete slabs requiring carpet or VCT? We are working on a fast track project that has 98% RH in the concrete and we need to get down to the 70s to apply the floor finish. The flooring installer has offered to apply a mitigation product for $8psf! Our VCT is only worth $2psf. I could have used stone and skipped the mitigation! Does anyone know of any innovative solutions that do not cost an arm and a leg? J. Peter Jordan (Unregistered Guest) Unregistered guest Posted on Saturday, November 13, 2010 - 10:43 am:    The $8.00/sf sounds like what I heard for these products about 10 years ago when we first began to need them. There are a number of mitigation systems that will go down in the neighborhood of $3.00/sf. Still makes VCT and Carpet look expensive. I think Prosoco makes one. Jim Sliff Advanced Member Username: jim_sliff Post Number: 5 Registered: 08-2010 Posted on Saturday, November 13, 2010 - 11:53 am:    The price sounds very high; I'd expect it to be 1/3-1/2 that figure, at least in Southern California. There are several "crystal-forming barrier" products (Some manufacturers are Xypex, Gaco, Hey'di, Tremco, Meadows - it's long list and you can Google "crystalline waterproofing" to find someone with local representation) that may work. Check with them specifically for horizontal-grade, vapor/moisture drive reduction products, as the vertical-grade types usually are not sufficient. I'd also specify inspection by the manufacturer or rep and a warranty. Examine a sample warranty carefully in advance - many initially include "affected areas only", "dollar limit" or "removal/replacement of any installed flooring system is not included" clauses that should be eliminated. That *will* kick the price up a tad, but it still should be (IMO) somewhere in the <$6/sf range. Yep - it's more expensive than the VCT; that's the kicker, and there's no cheap solution. I'd be leery about even stone installation if testing shows moisture content above 10%. That's a little lower than even the wood floor people set as a minimum but having seen hundreds of failures I'm REAL conservative - even at that level I've seen stone with grout joints growing white efflorescence "hair", which eventually infests the stone as well. Jim Sliff Senior Member Username: jim_sliff Post Number: 6 Registered: 08-2010 Posted on Saturday, November 13, 2010 - 12:18 pm:    I needed to look something up and just missed the edit time window - The moisture percentage is not normally a recommended test to determine suitability for installation of flooring systems, but is a practical field test that may reveal potential problems. There are two other tests - calcium chloride (ASTM F1869) and relative humidity (ASTM F-2170); the RH test is relatively unknown in the US but is widely used in Europe; generally anything over 75% is a problem. Calcium chloride testing should be done in tandem with RH or meter testing and CC results over 3#/1000sf/24hrs *regardless* of the other test results should be cause for mitigation before installation of any flooring system IMO. Sheldon Wolfe Senior Member Username: sheldon_wolfe Post Number: 452 Registered: 01-2003 Posted on Saturday, November 13, 2010 - 12:36 pm:    Get some of that pre-VOC limits mastic! I sometimes wonder if the extra materials and energy consumed in trying to fix flooring that won't stick offsets whatever benefit derives from eliminating the old mastics. We have specified an Ardex system. I prefer to make it an as-needed system, used only when tests indicate the flooring probably won't stick. The problem is that if it's required as part of the base bid, you don't know if it worked or not. If you have no problems with the flooring, it might be because the moisture control system worked, or it might be because it wasn't needed. Anne Whitacre, FCSI CCS Senior Member Username: awhitacre Post Number: 1050 Registered: 07-2002 Posted on Saturday, November 13, 2010 - 03:47 pm:    there are a couple of solutions and one of them is relatively cheap: wait until the floor dries. I had one project where the owner simply agreed to wait for three months (between college quarters) and apply the VCT at that time, when it easily met the requirements. The other is to find an adhesive that is not affected by water and just use that. Like Sheldon, I consider the floor mitigation a contractor schedule issue. On most of the projects I work on there is enough time in the schedule for the slab to dry out enough for the finish flooring to be installed -- assuming the contractor doesn't let a hose leak all over the floor or have standing water on the site continually. (invariably when the contractor complains that the "slab is too wet" its because they messed up somewhere along the line, not because the schedule is compressed). But yes, a non-water soluble adhesive might just take care of your problem. They still make them. Phil Kabza Senior Member Username: phil_kabza Post Number: 462 Registered: 12-2002 Posted on Monday, November 15, 2010 - 02:38 pm:    Our client Koster offers what is probably the best known tested solution for high moisture/high alkalinity concrete floor slab treatment in the form of a one- or two- coat epoxy application formulated specifically for this application. More information on their website (www.koesterusa.com). [corrected url - Colin] Dale Hurttgam, NCARB, AIA,LEED AP, CSI Senior Member Username: dwhurttgam Post Number: 73 Registered: 10-2005 Posted on Monday, November 15, 2010 - 04:09 pm:    We have encountered similar problems on some projects with the midigation typically running in the range of $4.00 s.f. We have not used it or really investigated it yet, but we are told that Mapei has a midigation product that only runs about 20 cents a square foot. This product does not require the floor prep that most other prodducts do. We typically build in a "unit cost" so that we build in a midigation cost factor up front. (Unregistered Guest) Unregistered guest Posted on Monday, November 15, 2010 - 01:26 pm:    A few years back we had a moisture caused flooring failures that occured at the same spot on 4 or 5 upper floors. A quick glance at some old construction photos confimed that this was the location of the construction crane block out. Unlike the rest of each floor plate, that concrete had not been poured until after the building was topped out and closed in. Wayne Yancey Senior Member Username: wayne_yancey Post Number: 376 Registered: 01-2008 Posted on Monday, November 15, 2010 - 04:36 pm:    Dale, Do you mean "mitigation" or are you using Archie Bunker speak? LOL ;O)> Randall A Chapple, AIA, SE, CCS, LEED AP Senior Member Username: rachapple Post Number: 38 Registered: 12-2005 Posted on Tuesday, November 16, 2010 - 01:12 pm:    I have been told by Mapei that there mitigation product does require that the floor be blast- tracked prior to application. Paul Gerber Senior Member Username: paulgerber Post Number: 41 Registered: 04-2010 Posted on Tuesday, November 16, 2010 - 03:35 pm:    The two Mapei products that my friendly, neighbourhood architectural rep told me about recently are: - Planiseal MRB (Moisture Reduction Barrier) - up to 15lbs (6.80kg) MVER and 85% RH - Planiseal EMB (Premium Epoxy Moisture Barrier) - up to 20lbs (11.3kg) MVER and 95% RH I did not think to ask for budget costs as we have never had to use these nor do we spec any mitigation products. I also have never used either of these products on site...but at least it gives you products to add to your research. Ride it like you stole it!!! Adam Schwegel New member Username: adam_schwegel Post Number: 1 Registered: 11-2010 Posted on Tuesday, November 16, 2010 - 04:25 pm:    A cost of $8 per square foot is a little extreme, but is dependent on the amount of floor are you are looking to have treated. This cost is acceptable when considering the treatment of 500 square feet and excessive when treating 10,000 square feet. The type moisture-vapor-RH treatment product and accessories will also cause a cost impact. For controlling 98% RH (ASTM F2170) the floors must be mechanically prepared by shot blasting, moisture-vapor-RH treatment, primed and coated with a cement topcoat product to allow the new low voc adhesives to properly transfer. The cost of the moisture-vapor-RH treatment is commonly less than the cost of the primer and cement topcoat in most areas. A reading of 98% RH is excessive and most flooring adhesives, primers and VCT tile flooring requirements will be exceeded. The ASTM F2170 scale is 0 to 100% with 2-3%RH accuracy from the measuring equipment. The other factors to consider are moisture vapor emission (ASTM F1869) and alkalinity-pH of the substrate. Water vapor emission is the amount of moisture escaping from the substrate at a current interior conditioning and these readings can be a determining factor in sealing or not sealing the substrate. Since all concrete is alkaline by nature ranging from 12.0 to 13.8pH when its poured, the surface of the substrate will lower over time to a range of 7 to 9pH. This is one of the most important readings when considering a moisture-vapor-RH treatment. Many low end treatment products are very sensitive to alkalinity-pH levels. Standard flooring adhesives, primers and flooring products can maintain a low alkalinity-pH resistance of 9 to 10pH. Some manufactures have increased their moisture vapor emission and relative humidity ratings to tolerant higher moisture readings, but no movement on the alkalinity-pH tolerances. Tony Wolf, AIA, CCS, LEED-AP Senior Member Username: tony_wolf Post Number: 24 Registered: 11-2007 Posted on Thursday, February 10, 2011 - 10:56 am:    Is anyone aware of/specifying Water Vapor Reducing Admixture in concrete? We had an impressive presentation by a manufacturer that makes it sound like a magic elixir [he actually used that term] for concrete, especially with regard to flooring and vapor transmission problems. He indicated that using it is standard practice on the east coast and in other areas. I hope his claims are true, but can't find much support on the interweb. Wayne Yancey Senior Member Username: wayne_yancey Post Number: 424 Registered: 01-2008 Posted on Thursday, February 10, 2011 - 11:01 am:    Wow. Another silver bullet!!! Richard Gonser AIA CSI CCCA SCIP LEED Senior Member Username: rich_gonser Post Number: 20 Registered: 11-2008 Posted on Thursday, February 10, 2011 - 11:29 am:    This sounds like a re-application/re-marketing of the crystalline admixture below grade waterproofing we've seen. Part of the issue will be with the glues that hold a finish floor down; is the bonding with the concrete. The water may not come up through the slab, but what about the zero VOC, water-based glue bonding with the top layer of the concrete? I would need to see actual products in use other than accelerated lab tests. Dale Hurttgam, NCARB, AIA,LEED AP, CSI Senior Member Username: dwhurttgam Post Number: 74 Registered: 10-2005 Posted on Thursday, February 10, 2011 - 01:22 pm:    There is a related thread under Specifications - Vapor Barrier performance for slabs on grade - that relates to preventing this problem. We have encountered moisture issue several times - exceeding 3# per 1000 s.f. Remediation has run in the range of $4.00 a sq. /ft. Have also heard that Mapei has a remediation product that does not require shot blasting and runs around 20 cents a sq./ft. installed. Have not investigated it as of this time. We typically specify an Allowance to remediate the floor if it does not meet testing requirements so at least a cost is identified up front. Lynn Javoroski CSI CCS LEEDŽ AP SCIP Affiliate Senior Member Username: lynn_javoroski Post Number: 1193 Registered: 07-2002 Posted on Thursday, February 10, 2011 - 01:32 pm:    We've begun including a CYA section as well and have included the Koester and Creteseal products. Construction schedules are just not allowing the proper time for concrete curing.