Moisture MitigationMoisture Mitigation

How they work and what to use.How they work and what to use.

Concrete Open or Close System?Concrete Open or Close System? Open system: Slab in contact with earthOpen system: Slab in contact with earth

• Greater opportunity for introduction of water post Greater opportunity for introduction of water post construction.construction.

• It is prudent to consider any slab of age to be an open It is prudent to consider any slab of age to be an open system. (compromised closed system design)system. (compromised closed system design)

Close System: Slab separated with a vapor “barrier” Close System: Slab separated with a vapor “barrier” • Recommended within ASTM F710Recommended within ASTM F710• Greater protection from introduction of water post Greater protection from introduction of water post

construction, but not bullet proof and often times not construction, but not bullet proof and often times not constructed according to ASTM F710.constructed according to ASTM F710.

Unfortunately, a vapor barrier’s purpose from a construction point of view differs from the floor covering industry’s and building occupier’s perspective. In truth, most vapor barriers at the time of slab pour are intended to trap the necessary water required for proper curing. They are typically specified at 6ml polyethylene sheeting which is not an adequate barrier for long term protection from moisture migration.

Closed System:Closed System:

Grade:Grade:Below Grade

On Grade

Above Grade

Moisture Mitigation Systems may not compatible with all slab designs.

Care must be taken to select the system best suited not only for the MVER/PH conditions, but also for the type of slab construction, its underlying structure (open or closed), and etc.

A perforated pan slab pour above grade is considered an “open” system for example.

Concrete: where is the water?Concrete: where is the water? Why do floors fail?Why do floors fail? Types of Mitigation SystemsTypes of Mitigation Systems Potential failuresPotential failures

Free WaterFree Water Water of convenience needed for slab finishingWater of convenience needed for slab finishing

Bound WaterBound Water Chemically binds and never leavesChemically binds and never leaves

Hydrostatic pressureHydrostatic pressure Water forced into and upward through the slab Water forced into and upward through the slab

Lateral MigrationLateral Migration Water introduction into the slab from an outside Water introduction into the slab from an outside

sourcesource

Water SourcesWater Sources

Free water This water is found within the

capillaries of the slab and will begin to evaporate if given the correct conditions.

Bound water This is the water that is

permanently bound as an integral part of the concrete slab.

Once the slab is poured and finished, “bleed water” runs off and the remaining water within the slab is defined as:

HYDROSTATIC PRESSURE

HHow water enters a building

LATERAL MIGRATION

How water enters a building

Water in the form of a vapor is moved from the bottom to the surface through the capillaries within the slab. Higher porosity (over watered slab) will allow this process to occur more freely. Water comes into contact with the adhesive/slab bond line and attacks the integrity of the adhesive.

As a Vapor

How water moves through a slabHow water moves through a slab

How water moves through a slabHow water moves through a slab

As a Liquid

Water has filled the capillaries completely just as a soaked sponge is completely wet.

Alkalinity’s effectAlkalinity’s effect As the water vapor migrates up through the slab, it will condense As the water vapor migrates up through the slab, it will condense

and form liquid water at the bond line between the slab and the and form liquid water at the bond line between the slab and the adhesive. This solution then becomes alkaline and will harm acrylic adhesive. This solution then becomes alkaline and will harm acrylic adhesives. adhesives.

What is PH?What is PH? PH is the measure of Hydrogen ions (acid) or Hydroxide ions PH is the measure of Hydrogen ions (acid) or Hydroxide ions

(alkalinity) in a water-based system. PH is measured on a (alkalinity) in a water-based system. PH is measured on a logarithmic scale from 0(acid) to 7(neutral) to 14(alkaline). Because logarithmic scale from 0(acid) to 7(neutral) to 14(alkaline). Because the PH scale is logarithmic, each point represents a 10 fold the PH scale is logarithmic, each point represents a 10 fold increase in alkalinity. A PH of 9 is 10 times more alkaline than a PH increase in alkalinity. A PH of 9 is 10 times more alkaline than a PH of 8. Gerflor does not recommend a PH higher than 8.5.of 8. Gerflor does not recommend a PH higher than 8.5.

Why is moisture a problem?

Vapor PressureVapor Pressure

Even with adhesives that are resistant to alkalinity and moisture, as Even with adhesives that are resistant to alkalinity and moisture, as the adhesive is bonded to the surface of the slab pressure can build the adhesive is bonded to the surface of the slab pressure can build beyond the cohesive strength of the adhesive and release. The beyond the cohesive strength of the adhesive and release. The typical evidence of this is random bubbling. typical evidence of this is random bubbling.

It will usually start in an area or areas and gradually work its way It will usually start in an area or areas and gradually work its way outward as the condition remains or worsens.outward as the condition remains or worsens.

Corrective Measures:Corrective Measures:

Remove and re-pour slabRemove and re-pour slab Topically applied mitigation systemTopically applied mitigation system Install slip sheet membraneInstall slip sheet membrane

Topically Applied Mitigation SystemsTopically Applied Mitigation Systems

PenetratingPenetrating Epoxy CoatingEpoxy Coating Dense Cementitious OverlayDense Cementitious Overlay SealersSealers Single system approach (adhesive= Single system approach (adhesive=

moisture/ph resistance and bonding agent)moisture/ph resistance and bonding agent)

Penetrating SealersPenetrating Sealers

Penetrating type reactive sealers are liquid applied treatments that Penetrating type reactive sealers are liquid applied treatments that chemically react with the concrete reducing the MVER and bind alkali chemically react with the concrete reducing the MVER and bind alkali

below the bond line.below the bond line. These are typically silicate in nature (sodium, lithium, or potassium)These are typically silicate in nature (sodium, lithium, or potassium) Some concrete mixtures will affect the efficacy of these types of Some concrete mixtures will affect the efficacy of these types of

sealants in relation to moisture/ph suppression and bonding sealants in relation to moisture/ph suppression and bonding compatibility with flooring adhesives. compatibility with flooring adhesives.

Silicate type treatments are considered by some with much less Silicate type treatments are considered by some with much less confidence than other topically applied products.confidence than other topically applied products.

Epoxy CoatingsEpoxy Coatings

There are single and multiple coat systems available.There are single and multiple coat systems available. Many systems designed for very high moisture/ph conditionsMany systems designed for very high moisture/ph conditions Designed to reduce MVER to a tolerable level at the bond line.Designed to reduce MVER to a tolerable level at the bond line. Isolates PH from flooring system.Isolates PH from flooring system. Typical that slab must be abraded through grinding or shot blasting.Typical that slab must be abraded through grinding or shot blasting. Typical that a cementitious over lay is required due to type of adhesive Typical that a cementitious over lay is required due to type of adhesive

used for the floor covering and/or repair trenching caused by concrete used for the floor covering and/or repair trenching caused by concrete surface preparation.surface preparation.

May include a broadcast. May include a broadcast.

Dense Cementitious OverlayDense Cementitious Overlay

Usually requires preparation of the slab’s surfaceUsually requires preparation of the slab’s surface Primer is applied prior to top coatPrimer is applied prior to top coat Highly densified cementitious layer is poured (may be self-leveling)Highly densified cementitious layer is poured (may be self-leveling) Floor patching as needed to bring to floor coverings required levelness Floor patching as needed to bring to floor coverings required levelness

benchmark.benchmark. Isolates slab from floor covering system.Isolates slab from floor covering system.

Top Coat SealersTop Coat Sealers

Typically used for lower MVER/PH conditions (approx. 8 lbs)Typically used for lower MVER/PH conditions (approx. 8 lbs) May or may not require slab surface preparation depending upon May or may not require slab surface preparation depending upon

surface condition of the slab (porosity, existing residues/sealers, etc.)surface condition of the slab (porosity, existing residues/sealers, etc.) Designed to reduce MVER/PH to a tolerable level.Designed to reduce MVER/PH to a tolerable level. Not typically recommended for open slab systems. Not typically recommended for open slab systems. May or may not be recommended for below grade slabs.May or may not be recommended for below grade slabs. One of the least expensive systems to apply.One of the least expensive systems to apply. Typically a high solids water based product. Typically a high solids water based product. May be “elastomeric”. Caution should be applied to these in May be “elastomeric”. Caution should be applied to these in

combination with certain types of resilient floor covering.combination with certain types of resilient floor covering.

Single System ApproachSingle System Approach

New adhesive products designed to seal the slab and act as a New adhesive products designed to seal the slab and act as a bonding agent in one step.bonding agent in one step.

• Water based acrylic adhesiveWater based acrylic adhesive

• Moisture cure urethane adhesiveMoisture cure urethane adhesive EconomicalEconomical Designed for lower MVER/PH conditionsDesigned for lower MVER/PH conditions May or may not be designed for certain types of floor coveringMay or may not be designed for certain types of floor covering May or may not be recommended for open slab systems.May or may not be recommended for open slab systems.

Slip Sheet MembranesSlip Sheet Membranes

Typically incorporate the use of a urethane adhesive in Typically incorporate the use of a urethane adhesive in combination with a low permeance vapor barrier.combination with a low permeance vapor barrier.

Essentially “free floats” accommodating minor cracks and joints.Essentially “free floats” accommodating minor cracks and joints. Typically shot blasting or grinding is not required.Typically shot blasting or grinding is not required. Not necessarily compatible with all flooring systems.Not necessarily compatible with all flooring systems. Effectively isolates floor covering away from the slab alleviating Effectively isolates floor covering away from the slab alleviating

build up of vapor pressure. (vapor moves laterally)build up of vapor pressure. (vapor moves laterally) PH resistantPH resistant

Pitfalls of selectionPitfalls of selection Generally price driven as the discovery of the problem doesn’t occur Generally price driven as the discovery of the problem doesn’t occur

until just prior to installation of the floor covering.until just prior to installation of the floor covering. Lack of investigation.Lack of investigation. Incomplete system that does not include accommodations for cracks or Incomplete system that does not include accommodations for cracks or

joints.joints. WarrantiesWarranties System requires “certification” prior to purchase and applicationSystem requires “certification” prior to purchase and application Cost Cost Incorrect system chosen for existing conditionsIncorrect system chosen for existing conditions Liability/Support if failure occursLiability/Support if failure occurs Incorrect application or slab preparationIncorrect application or slab preparation

Who pays?Who pays? Conditions above the tolerance level of the floor covering system Conditions above the tolerance level of the floor covering system

on new construction projects usually involves incorrect design on new construction projects usually involves incorrect design and/or construction. Unfortunately, this is often not discovered and/or construction. Unfortunately, this is often not discovered until just prior to installation of the floor covering. As contractors, until just prior to installation of the floor covering. As contractors, we can not assess who is the responsible party to cover we can not assess who is the responsible party to cover potential mitigation costs, but it is certain that these expenses potential mitigation costs, but it is certain that these expenses should not be absorbed by the floor covering contractor.should not be absorbed by the floor covering contractor.

Contractors must be very cautious also with existing slabs. Due Contractors must be very cautious also with existing slabs. Due diligence through careful inspection, investigation, and testing diligence through careful inspection, investigation, and testing according to industry practices and the mitigation suppliers according to industry practices and the mitigation suppliers recommendations is compulsory prior to making any recommendations is compulsory prior to making any recommendation for a specific mitigation system.recommendation for a specific mitigation system.

The problem is not a problem…The problem is not a problem…

until it becomes a problem.until it becomes a problem.

Caution is strongly advised if a contractor makes a personal Caution is strongly advised if a contractor makes a personal recommendation for any moisture mitigation system. Choose a system that recommendation for any moisture mitigation system. Choose a system that is appropriate for the conditions and/or potential conditions. Select a is appropriate for the conditions and/or potential conditions. Select a system that has a history of performance and customer service in the event system that has a history of performance and customer service in the event of a claim. All to often, moisture mitigation providers are quick to lay claim of a claim. All to often, moisture mitigation providers are quick to lay claim to contractor error before performing due diligence to discover the actual to contractor error before performing due diligence to discover the actual problem and offer a means to correct it. If a mitigation provider requires problem and offer a means to correct it. If a mitigation provider requires training, do not short cut this requirement. If experience or confidence is training, do not short cut this requirement. If experience or confidence is lacking, it is prudent to provide a list of mitigation providers to the General lacking, it is prudent to provide a list of mitigation providers to the General Contractor, Architect, or End User that they can contact for direct Contractor, Architect, or End User that they can contact for direct communication and recommendation. communication and recommendation.

Testing prior to recommendation:Testing prior to recommendation:

Most moisture mitigation systems require traditional moisture Most moisture mitigation systems require traditional moisture testing as outlined in ASTM F1869 commonly referred to as testing as outlined in ASTM F1869 commonly referred to as Calcium Chloride tests. These determine the MVER (moisture Calcium Chloride tests. These determine the MVER (moisture vapor emission rate) of the surface of the slab at the time of vapor emission rate) of the surface of the slab at the time of testing. Other tests may also be applicable including the “mat” testing. Other tests may also be applicable including the “mat” test, or the In-Situ probe test (ASTM F2170). All tests should be test, or the In-Situ probe test (ASTM F2170). All tests should be performed by an experienced testing professional (a third party performed by an experienced testing professional (a third party not financially vested into the project) complying to the required not financially vested into the project) complying to the required testing protocol and completely documenting the results. These testing protocol and completely documenting the results. These results should be forwarded to the GC, Architect, and/or End results should be forwarded to the GC, Architect, and/or End User prior to selection of the mitigation system to be used.User prior to selection of the mitigation system to be used.

THANK YOUTHANK YOU