subfloor preparation and moisture mitigation “an ounce of prevention is worth a pound of cure”...
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Subfloor Preparation Subfloor Preparation and Moisture Mitigationand Moisture Mitigation
““an ounce of prevention is worth a an ounce of prevention is worth a pound of cure”pound of cure”
Benjamin FranklinBenjamin Franklin
OutlineOutline
Concrete Slab BasicsConcrete Slab Basics Moisture Sources and Testing MethodologiesMoisture Sources and Testing Methodologies Repairing Defects in Concrete SurfacesRepairing Defects in Concrete Surfaces Crack Repair TreatmentsCrack Repair Treatments Treatments for Moisture Vapor Emission Treatments for Moisture Vapor Emission
Concrete BasicsConcrete Basics
CementCement Supplementary Supplementary
MaterialsMaterials AggregatesAggregates WaterWater
Moisture SourcesMoisture Sources
Water of HydrationWater of Hydration Water required to complete chemical reactionWater required to complete chemical reaction
• Typically considered ~25% of cement by weightTypically considered ~25% of cement by weight
Water of ConvenienceWater of Convenience Water used for ease of workability and placementWater used for ease of workability and placement
• Usually another 25% to 40% of cement by weightUsually another 25% to 40% of cement by weight
Moisture Vapor Transmission (MVT)Moisture Vapor Transmission (MVT) Water of convenience evaporatingWater of convenience evaporating
• 4” slab poured at .50 W/C evaporates >½ gallon per sq ft.4” slab poured at .50 W/C evaporates >½ gallon per sq ft.
Water coming up through the concrete from under slabWater coming up through the concrete from under slab
Water in the SlabWater in the Slab
Free waterFree water This water is found within This water is found within
the capillaries of the slab the capillaries of the slab and will begin to evaporate and will begin to evaporate if given the correct if given the correct conditions.conditions.
Bound waterBound water This is the water that is This is the water that is
permanently bound as an permanently bound as an integral part of the concrete integral part of the concrete slab.slab.
Concrete Curing/DryingConcrete Curing/Drying
All concrete requires All concrete requires time to “dry”. time to “dry”. 4” concrete slab with a 4” concrete slab with a
0.5 w/c ratio over an 0.5 w/c ratio over an impermeable moisture impermeable moisture barrier will take barrier will take approximately 92 days approximately 92 days to get to a suitable to get to a suitable level for wood floor level for wood floor installation installation
Reference: “Are your slabs dry enough for floor coverings?” By Bruce Suprenant and Ward R. Malisch, Copyright 1998
Drying of ConcreteDrying of Concrete
Thickness of concrete Thickness of concrete slab also impacts slab also impacts drying timedrying time
Open or Closed SystemOpen or Closed System
Open system: Slab in contact with earthOpen system: Slab in contact with earth Greater opportunity for introduction of water post construction.Greater opportunity for introduction of water post construction. It is prudent to consider any slab of age to be an open system. It is prudent to consider any slab of age to be an open system.
(compromised closed system design)(compromised closed system design)
Closed System: Slab separated with a vapor “barrier” Closed System: Slab separated with a vapor “barrier” Recommended within ASTM F710Recommended within ASTM F710 Greater protection from introduction of water post construction, Greater protection from introduction of water post construction,
but not bullet proof and often times not constructed according to but not bullet proof and often times not constructed according to ASTM F710.ASTM F710.
Basic Concrete Slab ConstructionBasic Concrete Slab Construction
Site evaluationSite evaluation Compressed soilCompressed soil Large aggregate (capillary Large aggregate (capillary
break)break) Smaller aggregateSmaller aggregate
Moisture barrier Moisture barrier specificationsspecifications
0.010” thick reinforced film0.010” thick reinforced film
Exterior Drainage and Exterior Drainage and Landscaping concernsLandscaping concerns
Closed System Closed System
A vapor barrier’s purpose from a A vapor barrier’s purpose from a construction point of view differs construction point of view differs from the floor covering industry’s from the floor covering industry’s and building occupier’s and building occupier’s perspective. Vapor barriers at the perspective. Vapor barriers at the time of slab pour are intended to time of slab pour are intended to trap the necessary water required trap the necessary water required for proper curing. Not an for proper curing. Not an adequate barrier for long term adequate barrier for long term protection from moisture protection from moisture migration. migration.
How Moisture Moves Through a How Moisture Moves Through a SlabSlab
On grade concreteOn grade concrete Capillary & MVTCapillary & MVT
Below grade concreteBelow grade concrete Capillary, MVT & Capillary, MVT &
Hydrostatic PressureHydrostatic Pressure
Moisture Testing per ASTMMoisture Testing per ASTM
Ravages of MoistureRavages of Moisture
Amount of Moisture Extracted MVE of 20 lbs./1,000 sq. ft. (9,07 kg per 92,9 m)/ 24 hours
7 Days of Extracted Moisture
20lb MVER
Roughly 16 gallons of water over a 7 day period over an area approximately 31’x31’
Flooring Moisture IssuesFlooring Moisture Issues
Solutions for Moisture ControlSolutions for Moisture Control
Silicate Penetrating SealersSilicate Penetrating Sealers Topical SealersTopical Sealers Epoxy CoatingsEpoxy Coatings Cementitious OverlayCementitious Overlay Single system approach (adhesive acts as Single system approach (adhesive acts as
bonding agent and moisture control solution)bonding agent and moisture control solution)
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.chemically react with the concrete reducing the MVER.
There are also products that are incorporated into the product at the There are also products that are incorporated into the product at the time of pour. (mixed in the truck)time of pour. (mixed in the truck)
These may be silicate in nature (sodium, lithium, or potassium)These may be 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 productsconfidence than other topically applied products
Top Coat SealersTop Coat Sealers
Typically used for lower MVER/PH Typically used for lower MVER/PH conditions (approx. 8 lbs)conditions (approx. 8 lbs)
May not require slab surface May not require slab surface preparation depending upon preparation depending upon surface condition of the slab surface condition of the slab
Not typically recommended for Not typically recommended for open slab systems. open slab systems.
May not be recommended for May not be recommended for below grade slabs.below grade slabs.
Creates “non-porous” substrateCreates “non-porous” substrate
Epoxy CoatingsEpoxy Coatings
There are single and multiple coat There are single and multiple coat systems available.systems available.
Designed for very high moisture/ph Designed for very high moisture/ph conditionsconditions
Designed to reduce MVER to a Designed to reduce MVER to a tolerable level at the bond line.tolerable level at the bond line.
Isolates PH from flooring system.Isolates PH from flooring system. Typical that slab must be abraded Typical that slab must be abraded
through grinding or shot blasting.through grinding or shot blasting. Typical that a cementitious over lay is Typical that a cementitious over lay is
required due to type of adhesive used required due to type of adhesive used for the floor covering and/or repair for the floor covering and/or repair trenching caused by concrete surface trenching caused by concrete surface preparation.preparation.
May include a sand broadcastMay include a sand broadcast
Concrete Profiles for Epoxy Concrete Profiles for Epoxy MembranesMembranes
Dual Function Adhesive SystemsDual Function Adhesive Systems
New adhesive products designed New adhesive products designed to seal the slab and act as a 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
Typically designed for a maximum Typically designed for a maximum of 15lbs MVER and 90% RHof 15lbs MVER and 90% RH
May not be designed for certain May not be designed for certain types of floor coveringtypes of floor covering
May or may not be recommended May or may not be recommended for open slab systems or slabs for open slab systems or slabs with hydrostatic pressure.with hydrostatic pressure.
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 Highly densified cementitious layer is poured (may be
self-leveling)self-leveling) Floor patching as needed to bring to floor coverings Floor patching as needed to bring to floor coverings
required levelness benchmark.required levelness benchmark. Isolates slab from floor covering system.Isolates slab from floor covering system.
Slip Sheet MembranesSlip Sheet Membranes
““Free floats” accommodating Free floats” accommodating minor cracks and joints.minor cracks and joints.
Shot blasting or grinding is not Shot blasting or grinding is not required.required.
Not necessarily compatible Not necessarily compatible with all flooring systems.with all flooring systems.
Effectively isolates floor Effectively isolates floor covering away from the slab covering away from the slab alleviating build up of vapor alleviating build up of vapor pressure. (vapor moves pressure. (vapor moves laterally)laterally)
PH resistantPH resistant
Decisions Drivers and Pitfalls for Decisions Drivers and Pitfalls for Moisture Solution SelectionMoisture Solution Selection
Amount of remediation required (MVER and RH Levels)Amount of remediation required (MVER and RH Levels) Available funds (Moisture Issues not typically expected) Available funds (Moisture Issues not typically expected) Incorrect system chosen for existing conditions / Lack of investigation.Incorrect system chosen for existing conditions / 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. System requires “certification” prior to purchase and application / WarrantiesSystem requires “certification” prior to purchase and application / Warranties Liability/Support if failure occursLiability/Support if failure occurs Incorrect application or slab preparationIncorrect application or slab preparation
REPAIRING DEFECTS IN REPAIRING DEFECTS IN CONCRETE SURFACESCONCRETE SURFACES
Minor Defect RepairsMinor Defect Repairs
Cement Based with Liquid Cement Based with Liquid Polymer AdditivesPolymer Additives
Dry Polymer Modified Cement Dry Polymer Modified Cement basedbased
Dry Polymer Modified Gypsum Dry Polymer Modified Gypsum based (residential and light based (residential and light commercial use)commercial use)
High hydrating, polymer and High hydrating, polymer and fiber reinforced cement based fiber reinforced cement based underlayments (skim coats)underlayments (skim coats)
Typical Usages: From Feather Typical Usages: From Feather egde to 1-1.5” Thickness in egde to 1-1.5” Thickness in single applicationsingle application
Use “exterior rated” patching compounds on slabs with moisture issues.
Large Area RepairsLarge Area Repairs
Self Leveling Self Leveling UnderlaymentsUnderlayments
PrepPrep• Make sure the substrate has Make sure the substrate has
the proper CSP or profile to the proper CSP or profile to receive the levelerreceive the leveler
PrimePrime• Select the right primer for the Select the right primer for the
substratesubstrate PourPour
• Follow all instructions on the Follow all instructions on the package package
Wait 3 days for floor covering Wait 3 days for floor covering installationinstallation
Deep Fill RepairsDeep Fill Repairs
ScreedsScreeds Typical fills up to 4” Typical fills up to 4”
thickthick Cure time relatively Cure time relatively
quick but reset the quick but reset the clock in terms of clock in terms of flooring acceptance as flooring acceptance as much as 30 daysmuch as 30 days
Concrete Profiles for Self Leveling Concrete Profiles for Self Leveling UnderlaymentsUnderlayments
Crack RepairCrack Repair
Mechanically prepare control and Mechanically prepare control and construction/expansion joints with a construction/expansion joints with a diamond crack-chasing/concrete-diamond crack-chasing/concrete-cutting blade. cutting blade.
Overcut the joint width to obtain a Overcut the joint width to obtain a sound, clean edge. sound, clean edge.
Clean cracks or joints with oil free Clean cracks or joints with oil free compressed air and/or vacuum with a compressed air and/or vacuum with a dustless collection system to dustless collection system to completely remove contaminants completely remove contaminants
An Engineer or Consultant determines if a crack is ‘dormant’ or ‘active’ and
which product to use
He who lives upon hope, dies fasting.He who lives upon hope, dies fasting. Benjamin FranklinBenjamin Franklin
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