Common Causes of FlooringFailures and How to Prevent
ThemHESNI 2015 Annual Conference
7 May 2015Emily O’Keefe
Simpson Gumpertz & Heger Inc. is a Registered Providerwith The American Institute of Architects ContinuingEducation Systems. Credit earned on completion of thisprogram will be reported to CES Records for AIAmembers. Certificates of Completion for non-AIAmembers are available on request.
This program is registered with the AIA/CES forcontinuing professional education. As such, it does notinclude content that may be deemed or construed tobe an approval or endorsement by the AIA of anymaterial of construction or any method or manner ofhandling, using, distributing, or dealing in any material orproduct. Questions related to specific materials,methods, and services will be addressed at theconclusion of this presentation.
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© Simpson Gumpertz & Heger Inc. 2015
Learning Objectives
1. Understand that moisture in concrete floors canlead to floor finish problems.
2. Identify good practices and preventativemeasures for limiting moisture levels in concretefloors.
3. Learn the current moisture test methods forconcrete, their limitations and how to interpretresults.
4. Learn how to evaluate and select measures tomitigate high moisture levels in concrete floors.
Presentation Outline
• Flooring Failures
• Typical Causes of Flooring Failures
• Why so many failures now?
• Minimizing the Risk
• Case Studies
5
Flooring Failures
Flooring Failures on Concrete
• Vinyl
– VCT
– Sheet
– Simulated Wood
• Hardwood
– Oak
– Ash
– Maple
– Bamboo
• Carpet
– Broadloom
– Carpet Tile
• Terrazzo
– Cementitious
– Epoxy
• Coatings
– Epoxy
– Urethane
– MMA
– Vinyl Ester
• Rubber Tile
• Silicates
• Stains
• Underlayments
Adhesive Failure
Vinyl Flooring Failures
Wood Flooring Failures
Carpet Failures
Resinous Terrazzo Failures
Coating Failures
Typical Causes ofFlooring Failures
Typical Causes of Flooring Failures
• Primary Causes
– Moisture
Sources of Moisture
• Underlying Soil
• Concrete
• Cleaning and Maintenance
• Ambient Conditions
Adhesive Staining + Sliding Tiles
Wet Concrete
Discolored Artificial Stone Tiles
Concrete Slab-on-GradeNo Vapor Retarder beneath Slab
Stains on Engineered Wood Flooring
Elevated Concrete Deck
Exposure to Exterior Moisture
Ruts in Sheet Vinyl with Soft, MigratingAdhesive
Elevated Concrete Deck
Epoxy Terrazzo Blisters and SurfaceDeposits
Concrete Slab-on-GradeVapor Retarder beneath Blotter Layer
Typical Causes of Flooring Failures
• Primary Causes
– Moisture
– Quality and Preparation of Concrete
Surface Preparation
• Surface preparation directly affects adhesion.
• Remove bond-breaking substances to improvechemical adhesion.
• Roughen surface and remove unsound materials toimprove mechanical adhesion.
Concrete Surface Profiles (CSP)
Concrete Surface Preparation Methods
Delaminated Ceramic Floor Tiles
Ineffective Surface PreparationContaminated Surface
Slippery White Deposits on WarehouseFloor
Surface Contamination of Silicate Hardener Residue
Blisters in Epoxy Floor Coating
Surface Contamination of Silicate Hardener Residue
Typical Causes of Flooring Failures
• Primary Causes
– Moisture
– Quality and Preparation of Concrete
• Secondary Causes
– Product Selection
– Cleaning and Maintenance
– Environmental Exposure (humidity, sun, etc.)
Product Selection Issues
System Selection Issues
System Selection Issues
Environmental Exposure
34
Environmental Exposure
35
Why So ManyFailures Now?
Why have we seen so many failuresnow?
• Change in materials (governmentregulations and environmentalconsiderations)
Asphalt Cutback Adhesives
SCAQMD Rule 1168 (2005)
Carpet Policy Dialogue
VOC Regulations by State or Region
Why have we seen so many failuresnow?
• Change in materials (governmentregulations and environmentalconsiderations)
• Blended cement (fly ash) concretes
Concrete with and without Fly Ash
Concrete microstructure withoutfly ash at 200X magnification.
Concrete microstructure with 20%fly ash at 200X magnification.
Why have we seen so many failuresnow?
• Change in materials (governmentregulations and environmentalconsiderations)
• Blended cement (fly ash) concretes
• Use of lightweight concrete
Normal Weight vs. Lightweight Concrete
• 110 to 115 pcf vs. 145 to 150 pcf
• Expanded slate and shale aggregate
Normal Weight vs. Lightweight Concrete
Figure from ACI 302.2R-06
Normal Weight vs. Lightweight Concrete
From Concrete International, January 2012
Why have we seen so many failuresnow?
• Change in materials (governmentregulations and environmentalconsiderations)
• Blended cement (fly ash) concretes
• Use of lightweight concrete
Why have we seen so many failuresnow?
• Change in materials (governmentregulations and environmentalconsiderations)
• Blended cement (fly ash) concretes
Why have we seen so many failuresnow?
• Change in materials (governmentregulations and environmentalconsiderations)
• Blended cement (fly ash) concretes
• Fast track construction
Minimizing theRisk
Minimizing the Potential for Floor Failures
• Concrete
• Testing
• Moisture Mitigation
52
Get It Dry and Keep It Dry
Minimizing the Potential for Floor Failures
• Concrete
• Testing
• Moisture Mitigation
53
Planning Ahead for Flooring Installation
54
Preconstruction
Start Construction
Concrete Placed
Building Enclosed
HVAC Operational Flooring Installed
Building Occupancy
REWETTING DRYING
In Progress Construction
Concrete Design
• Vapor retarder should comply with ASTME1643
• Prohibit the use of a sand blotter layer
56
Slab-on-Ground without a VaporRetarder
Slab-on-Ground without a VaporRetarder
Slab-on-Ground with a VaporRetarder
Location of the Vapor Retarder
From ACI 302.2R
Slab-on-Grade with Blotter Layer
Slab-on-Grade with Blotter Layer
Slab-on-Grade with Blotter Layer
Location of the Vapor Retarder
From ACI 302.2R
Installation of Sand Blotter Layer
Sand BlotterLayer
VaporBarrier
Preparation for Compaction of Blotter Layer
Concrete Design
• Limit water content (our typicalrecommendations):
– 0.40 maximum w/c ratio for NW concrete
– 0.45 maximum w/c ratio for LW concrete
– 300 lb/cyd maximum water content
– Use as large an aggregate size as possible
– Use a good aggregate gradation
• Limit fly ash and slag to 5-10%
67
Concrete Design
• Prohibit addition of water beyond approvedmix design in the field
• Water-reducing Admixtures
• Shrinkage-reducing Admixtures
– Consider for use with slabs-on-grade toreduce curling and cracking
68
Concrete Construction
• Floor Flatness (FF) and Floor Levelness (FL)
• Curing
69
Floor Flatness and LevelnessCoordination
70
Curing
• Moisture-retaining covers for flatwork toreceive flooring
71
Minimizing the Potential for Floor Failures
• Concrete
• Testing
• Moisture Mitigation
72
Tester Qualifications
• Proper Testing Equipment
• Experience Performing Tests
• Experience Interpreting Results
• ICRI Concrete Moisture Testing TechnicianCertification
– Training Seminar
– Written Examination
– Performance Examination
73
ASTM Moisture Test Standards
• ASTM F1869 – Standard Test Method forMeasuring Moisture Vapor Emission Rate ofConcrete Subfloor Using Anhydrous CalciumChloride
• ASTM F2170 – Standard Test Method forDetermining Relative Humidity in Concrete FloorSlabs Using in situ Probes
• ASTM F2420 – Standard Test Method forDetermining Relative Humidity on the Surface ofConcrete Floor Slabs Using Relative HumidityProbe Measurement and Insulated Hood
• ASTM F710 – Standard Practice for PreparingConcrete Floors to Receive Resilient Flooring
General Test Procedures
• Space at operational temperature andhumidity
• Three tests for first 1,000 ft2, one test for eachadditional 1,000 ft2 (10 yd3 truck covers 800ft2 at 4 in. thick)
• Do not concentrate test sites
75
ASTM F1869 – Moisture Vapor EmissionRate (MVER)
ASTM F1869: Procedures to Note
• Remove existing floor material
• Grind concrete surface
• Seal dome to concrete
• Test duration of 60 to 72 hrs
ASTM F1869: Results
• MVER = (52.91 * ΔM) / (A * T)
• MVER = lbs / 1,000 ft2 / 24 hrs (lbs)
• Maximum MVER = 3 lbs (per ASTM F710)
• Report should include the following:
– Any variations from the test standard.
– Ambient conditions during test.
– Identify any venting requirement.
ASTM F1869: Limitations of Test
• No documented scientific basis
• No calibration procedures or standardreference
• Only measures thin layer (1/2 in.) on surface
– Not a good indication of trapped moisture inlightweight concrete
ASTM F2170 – Internal Concrete RH
ASTM F2170: Procedures to Note
• Select appropriate depth for holes
– Slab Drying from Top Only: 40% Depthfrom Top of Slab
– Slab Drying from Top and Bottom: 20%Depth from Top of Slab
• Clean holes
• Seal sleeve
• Test duration of 72 hrs
ASTM F2170: Results
• RH = Water Vapor in Air (at a specific temp.)Maximum Water Vapor in Air (at same temp.)
• RH = %
• Maximum RH = 75% (per ASTM F710)
• Report should include the following:– Depth from top of slab, slab thickness,
“drying conditions.”
– Ambient temperature and humidity.
– Make and model of instruments used.
– Last calibration and calibration procedures.
ASTM F2170: Limitations of Test
• Newer method
• Limited thickness of slab
• Different probes give different results
Other Moisture Measuring Tools
ASTM F1869 vs. ASTM F2170
• So I conducted the tests properly, what dothe results mean?
ASTM F1869 vs. ASTM F2170
High RH Low RH
High MVER
Low MVER
ASTM F1869 vs. ASTM F2170
High RH Low RH
High MVER
Low MVER
• Average calculation not applicable, maximumvalue must be below limit.– Can consider breaking floor up into zones, but must be
clearly defined by floor, concrete pour, etc.
What Happens Next?
88
Moisture Mitigation
Minimizing the Potential for Floor Failures
• Concrete
• Testing
• Moisture Mitigation
89
Moisture Mitigation System
• We Recommend: Two-component, VOC compliant,low viscosity, 100% solids epoxyformulated as a vapor retarderagainst high moisture andalkalinity substrates (ASTMF3010)
• We Avoid: penetratingcoatings, water-basedmaterials, concrete admixtures
90
Moisture Mitigation
• Joint/Crack Treatment
– Manufacturerrecommended jointtreatment varies
91
Movement Joint Non-Movement Joint
Leveling Underlayment
• Required if using a water based adhesive
• Portland-cement-based (less than 13%gypsum content), self-leveling underlayment
– Primers
– Thicknesses
92
Case Studies
Case Study: Museum Warehouse
Blisters in Epoxy Coating
Liquid from Blister
Good Drainage on Site
No Issues with Uncoated Concrete
Blisters and Liquid under Epoxy Coating
Calcium Chloride MVER Tests
8.27
5.79
4.44
1.43
0.00
1.002.003.004.00
5.006.007.008.00
9.00
1 10 100 1000 10000
MVER vs. Hours after Coating Removal
Vapor Retarder over Existing Coating
Reinforced Topping Slab on New VaporRetarder
Curing of New Topping Slab
Application of New Coating on“Dry” Topping
Final Repair
Case Study: Elementary SchoolSlab-on-Grade
107
Flooring Deterioration
108
Existing Floor System
109
VAT
VCT
Floor Vent Pipes
110
Sub-Slab Construction
• Concrete floor slab is 5 in. thick• Sub slab soil is sandy-clay with 1 in. and
larger stones• Moisture content of the soil about 8% (dry
soil typically has less than 2% moisture)• No vapor retarder beneath concrete (to
depth of 17 in.)• Site drainage system functions
adequately• Water table at least six feet below
surface
111
Moisture Measurements
112
RoomMVER(lbs)
RH(%)
5 5.9 95
15 5.7 95
library 7.9 96
11 9.8 97
gym 8.2 92
Moisture Measurements
113
RoomMVER(lbs)
RH(%)
5 5.9 95
15 5.7 95
library 7.9 96
11 9.8 97
gym 8.2 92
Floor Venting System
• Direction of air movement through vents is intobuilding, regardless of roof-top vent fanperformance, so floor system receives outside air ona continual basis.– When outside air is warmer than floor, potential for
condensation within floor system exists.
– When outside air is cooler than floor, flooring system cancool, increasing potential for condensation to occur onsurface of flooring.
Buildings Mechanical System
• Interior dew point tracks with outside temperatureand humidity.
• Air flow is into building, drawing exterior humidity intorooms and corridors.
• Dew point occasionally becomes higher than floortemperature in late fall and in spring, potentiallycausing condensation on floor surface.
115
Sources of Moisture in and on Flooring
• From concrete, and soil beneathconcrete
• From roof venting system
• From open doors and windows
116
Repair Recommendations
• Remove flooring and tile to expose concrete surface(requires asbestos abatement)
• Shotblast concrete to remove residual adhesive• Seal surface of concrete with a topical moisture
mitigation membrane – including floor beneath cabinetsand heating units.
• Apply finish flooring system (leveling layer, adhesive, tile)• Adjust / replace doors and fixtures as needed• Repair openings left in roof from discontinued vents• Review mechanical system operation and balance
building– Install make-up air system to classrooms– Dehumidify air (either make-up or ambient)
117
Floor System Demolition
118
Concrete Surface Preparation
119
Floor Patching Requirements
120
Mitigation Coating Application
121
Finish Installation
122
Case Study: Wood Flooring in Condos
Floor System
1. Bamboo Strip Flooring
2. Strip Flooring to Underlayment Adhesive
3. Sound Attenuation Underlayment
4. Underlayment to Substrate Adhesive
5. Substrate
Failure Mechanism
• Bamboo swells (mostlyperpendicular to “grain”)due to change in moisturecontent after installation.
• System of soundattenuation underlaymentand adhesives cannotrestrain expansion.
• Underlayment/adhesivesystem fail at slabinterface.
• Bamboo floor buckles(“tents”) since bond tofloor had failed.
Stresses from Moisture Change
Conceptual cross section of installed flooring.
Increased moisture content causes flooring to swell. Swelling restrained by bond tosubstrate. Stresses in wood, underlayment and adhesive increase with increased
swelling.
Bond fails. Flooring allowed to swell and change length. Stresses in flooring are relieved.
Causes of Failure
• Bamboo is composite of bamboo fiberand adhesive which can expand andcontract with changes in moisture.– Acclimatization– Ambient conditions– Relatively low concrete slab moisture
• Sound isolation mat is not adequate tosupport bamboo.– Improper adhesive and adhesive application– Use of water-based adhesives– Allows expansion and contraction– Low tensile strength of mat
Mockup
• Three-ply, cross-grain, horizontal-laminated bamboo flooring (6 in. widestrip flooring planks).
• Urethane wood flooring adhesive.
• Moisture vapor protection and soundisolation barrier coating.
Mockup
Mockup
Case Study: Self Storage ConcreteComposition
Chemical Concrete Composition
132
Chemical Concrete Composition
Magnified Concrete – For Orientation
Sand
Aggregate
Cement
Typical ASR – Normal Light
Crack coming out of aggregatein perpendicular direction
Dark rim around aggregate
TYPICAL ASR – Thin Section, Colored by Polarized Light
Crack coming out of aggregatein perpendicular direction
Crack filled with gel
Crack in aggregateand filled with gel –
shown by pinkish color
The First Repair
The First Repair
The First Repair
Uh oh
Uh oh
The Second Repair
The Second Repair
The Second Repair
The Second Repair
Case Study: Coating in MaintenanceCenter
Delamination of Coating from Impact
Delaminated Coating Sample
Pull-Off Adhesion Tests
Pull-Off Adhesion Tests
Test No.Tensile Force
at Failure (psi)Plane of Failure
P-1 200 Between disc and adhesive
P-2 200 Cohesive within top layer of concrete
P-3 380 Between disc and adhesive
P-5 300 Cohesive within top layer of concrete
P-7 250 Cohesive within top layer of concrete
P-9 200 Cohesive within top layer of concrete
P-10 220 Cohesive within top layer of concrete
P-11 300 Cohesive within top layer of concrete
P-12 275 Cohesive within top layer of concrete
P-13 500 Between adhesive and concrete
P-15 300 Between disc and adhesive
P-16 50 Between adhesive and concrete
Concrete Petrography
Initial Recommendations
• Remove the coating system and aminimum of 5/16 in. of the surface of theslab.– Least aggressive form of surface preparation
that will remove the existing coating anddamaged surface layer of concrete
– Surface preparation techniques should beevaluated through mock-ups
• Coating system used is appropriate - itcan be reinstalled on a properlyprepared substrate.
Mockups
Remedial Options – Concrete SurfacePrep
• Shot Blasting
+ Removes coating and prepares concrete
– Causes damage to surface of concrete
• Scraping and Sand Blasting
+ Will prepare concrete without causingsignificant damage
– Two-step process to remove coating andprepare concrete
Remedial Options – Repair ConcreteSurface
• Gravity Fed Epoxy+ Easy to install
– May not fill all cracks
• Injected Epoxy+ Easier to install in smaller phased areas
– Labor intensive, time consuming, andineffective on small cracks
• Concrete grinding+ Can reliably remove all damaged concrete
– Time consuming due to required surfacerepairs
Remedial Options – Floor Finishes
• Tile (with uncoupling membrane)+ Easily phased, minimal moisture problems
– Aesthetic change, prone to impact damage
• Polished and Stained Concrete+ No curing time, high durability, no moisture
problems
– Poor resistance to staining, aesthetic change
• Epoxy Coating+ No aesthetic change, easily cleaned
– Must overcome concrete damage andmoisture levels
Mockups
• Level of shot blasting
• Gravity fed epoxymaterial
Mockups
Final Specification
• Shot blasting to ICRI CSP 3-5.
• Application ofmitigation/consolidation system diluted50% with acetone.
• Wait 48 hrs.
• Application of 100%mitigation/consolidation system.
• Wait 12 hrs.
• Application of epoxy coating system.
Repairs – Surface Preparation
Repairs – Epoxy Application
Repairs – Completed Coating
What’s Coming?
• Self-desicating concretes
• Other specialty concretes
• New moisture mitigation technologies,formulations, and formulation revisions
• Earlier and earlier application ofmoisture mitigation
• Waterproof and pH-proof adhesives
• Greener flooring materials
• Self-adhesive flooring materials
163
Summary
• Understanding moisture is critical to preventingfailure for flooring coverings and coatings onconcrete, especially with today’s water-basedand 100% solids adhesives and coatings.
• Limit the moisture in concrete by using a vaporretarder, controlling the mix design, andcontrolling the curing.
• The concrete slab is the substrate – design andconstruct it with that in mind.
• The flooring and adhesive type(s) dictaterequirements for the flooring and otherspecification sections.
• Include a moisture mitigation system in thespecification (base bid, add alternate, or unitprice) – surface preparation is key
This concludes The American Institute of ArchitectsContinuing Education Systems Program
Simpson Gumpertz & Heger Inc.
Thank you for your time.
QUESTIONS?
Section 033000 – Cast-in-Place Concrete
• Typical FF and FL Combinations and Descriptions
• Moderately Flat – FF25/FL20 – office building with carpet
• Flat – FF36/FL20 – shopping center or hospital public areawith thin-set coverings
• Very Flat – FF45/FL30 – very sensitive, includingwarehouses with air pallets
166
Rating
Slab-on-GradeSuspended Slabs
(shored)Suspended Slabs
(unshored)
OverallLocalMin.
OverallLocalMin.
OverallLocalMin.
FF25/FL20FF25/FL20 FF17/FL15 FF25/FL20 FF17/FL15 FF25 FF17
FF36/FL20FF36/FL20 FF24/FL15 FF30/FL20 FF24/FL15
FF30FF24
FF45/FL30 FF45/FL30 FF30/FL20--- ---- --- ---
Slab-on-Grade and Curling
Rebar near top of slab to prevent curlingand arrest cracking
Saw-cut control joint
Shrinkage-compensatingadmixture in concrete