Revision 01 - 30 August 2019

A11 - SUBSTRATE TESTING

A11-1 General
A11-2 Moisture
A11-3 Moisture and alkalinity testing requirements
A11-4 Moisture testing
A11-5 Moisture indication testing versus moisture testing
A11-6 Alkalinity testing
A11-7 Testing errors
A11-8 Mat Bond tests
A11-9 Acceptance of substrate surfaces
A11-10 Substrate Surface Water Absorption (Porosity) Testing
A11-11 Substrate Surface Temperature Testing
​A11-12 Concrete Surface Profile (CSP)
A11-13 Testing for delaminated or loose substrate material
​A11-14  (under review 2022)

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Preface: This reference guide covers testing of substrate surfaces for moisture and alkalinity as well as testing for adhesive bonding, but not substrate strength testing. Individuals using this guide should verify all facts relative to the particular project requirements.

1 • GENERAL

1. The construction community accepts the need for independent testing for a variety of validation and verification requirements associated with quality control and quality assurance. 
   1. The NFCA describes requirements for third‑party testing of substrate surfaces including moisture content, alkalinity, flatness and surface profile prior to floor covering installation start up.
2. The Constructor (the general contractor, construction manager or design‑builder) is responsible for engaging with and paying for third‑party testing of substrate surfaces, and correcting them to meet NFCA requirements for flatness, moisture content, porosity and alkalinity.
   1. Third‑party testing must be complete, and substrate conditions corrected before engaging with floor covering installation contractors.
   2. Floor covering installers will only perform minor surface preparation to align the prerequisite condition with surface conditions required by floor covering manufacturers.
   3. Failure to verify conditions and perform substrate corrections in a timely manner may delay installation of floor covering materials.

2 • MOISTURE

.01 The presence of excess moisture on or in a substrate that is to receive flooring materials can cause significant issues for floor covering products and related materials, particularly if the flooring material is of a type that will entrap or inhibit the transmission of moisture. Restricting Moisture Vapour Emission Rate (MVER) may lead to adhesive bond failure, deterioration of the floor covering product and adjacent materials.

.02    All new and old concrete surfaces, above, on, or below grade level shall be assessed for both moisture and alkalinity content in strict accordance with manufacturers requirements and stated ASTM tests.  

.03 Moisture in existing slabs can be present due to leaking pipes, sprinkler heads, condensation, dripping HVAC units, broken window seals, cracked foundations. 

Saturated concrete from broken door seal

Video shows leaking sprinkler pipes wetting the concrete surface beneath

.03    Where such tests have been conducted and documented and have shown acceptable conditions at the time of installation, subsequent failure of the floor covering, and/or  installation, or failure of the waterproofing or damp proofing membrane under the concrete slab due to the presence of moisture, shall not be the responsibility of the floor             covering Contractor.

.04    Repairs to the floor covering material, as a result of moisture or alkali damage from causes noted above, will be the responsibility of the General Contractor and/or Owner.

.05    Moisture Levels in Concrete Substrates

• The appearance of concrete can be deceiving and it is never safe to assume that such floors are dry due to the lack of visible moisture.


• Even with adequate curing time, concrete can still present an unacceptable moisture condition by allowing excessive amounts of moisture vapour to pass through to the surface. This can be a problem even on suspended concrete floors.


• Moisture levels in concrete can be affected by a number of factors. The following must be considered when testing concrete:


• Soil conditions of slabs on grade:
  • Wet or dry.
  • Expansive or non-expansive.
  • Free draining or non free draining.
  • Water table location (and as affected by seasonal / volume levels and/or tides).
  • Inert or contaminated soils and absorptive capacities.
  • Sub-base type (cut or fill).
  • Base type (included or omitted and if was compacted).
  • Screeding type (screed stakes or form screeding).
  
  Type of Concrete:
  • Water to cement ratio of mix design.
  • Type and grade of aggregate.
  • Time of transit from plant to site and any delays (for any reason).
  • Rotations used in each load.
  • Temperature of the concrete mix at time of delivery.
  • Slump at time of placement.
  • How much water, if any, was added during delivery and placement.
  • If water was added to the aggregate (lightweight concrete) and if it was factored into the water to cement calculations.
  • Curing method and materials used (impermeable sheet / wet cure, curing / sealing compounds, etc.) and for how long.
  • Finishing methods used (hard trowelled, power trowelled, etc.).
  • Admixtures used (e.g. calcium chloride, fly ash, plasticizers, water reducers, etc.).
  
  Building Envelope Condition and Environment:
  • Temperature of room.
  • Relative humidity of room.
  • Concrete surface temperature.
  • Air movement.

.06    Alkaline Levels in Concrete Substrates

• Alkalis are a soluble substance having a pH of more than 7 when dissolved in water, and also are referred to as bases. Alkali occurs in concrete and may be left as a residue on concrete substrate surfaces when the water carrying alkaline salts evaporates during the concrete curing process.
• Note: pH is the symbol used in conjunction with a number to indicate acidity or alkalinity levels. The numbers on the pH scale are 1 to 14 with 7 being neutral. Below 7 is acid while above 7 is alkaline.
  
  
  • Alkali can leave unsightly salt deposits at the seams of sheet flooring and along the joints of tile flooring. If excessive, alkali may actually corrode or burn the edges of the flooring. It can also build up under flooring causing bumps to occur or it may eat away at flooring adhesives causing adhesive bond failure and damage to the flooring itself. Alkali can also cause dusting of the concrete surface. Flooring adhesives are designed to be alkali resistant up to a pH of 9. Above 9, the alkali becomes excessive and can actually burn skin and start to dissolve concrete aggregate.
  
  
  • In summary, the presence of alkali can prevent or destroy adhesive bond, carpet backing, and resilient, and hardwood flooring if not eliminated

.07    Moisture Levels in Wood Substrates

• Wood substrates can contain moisture that is present in the subfloor sheathing and support framing (joists, etc.) materials when they are delivered to the site or absorbed during storage (if material is not covered) or in place if the building is not closed in and the flooring and support framing is exposed to the elements (rain, frost, snow, high humidity).

3 • MOISTURE AND ALKALINITY TESTING REQUIREMENTS

.01    Because there is precedence, and in fact, a broad acceptance in the construction industry for independent testing, the NFCA requires that a qualified third party inspection agency be used to test all substrate surfaces for moisture (specifically ASTM F-1869 Calcium Chloride and / or ASTM F-2170 RH In-Situ) and alkalinity levels.

.02    It will be the responsibility of the Contractor (General Contractor or Construction Manager) to provide and pay for such testing in a timely manner prior to installation start up.

.03    Moisture and alkalinity tests will be conducted using testing methods and devices in accordance with the particular floor covering manufacturer's recommendations and in accordance with NFCA testing and Quality Assurance Program requirements.

.04    The type of tests conducted, the location of each test, and testing results obtained shall be carefully recorded. The time of day and the site conditions in regard to weather,   temperature, and humidity will also be noted.

.05    All such testing will be conducted with ambient and substrate surface temperatures and humidity levels within ranges specified by the testing standard and material          manufacturers recommendations.

.06    The final test results must be in compliance with the manufacturer's recommendations for the adhesive and floor covering materials to be used and acceptable to NFCA      Quality Assurance Program requirements.

.07    It is the responsibility of the flooring contractor to verify that moisture and alkalinity tests have been conducted for all areas to receive flooring before installing any flooring     materials, and if necessary verify such results with their own moisture indicator testing.

4 • MOISTURE TESTING

.01    To determine the moisture level of a substrate the following steps must be taken:

• Visually inspect substrate surfaces for dampness, standing water, or water ingress or leakage from any source.


• Determine which type of test and testing equipment is recommended by the floor covering manufacturer for testing moisture emissions of the various substrate types, except that such measures will be no less than those required by NFCA.


• Determine the actual amount of moisture contained, or emitted from the substrates using the recommended testing method as a minimum.


• In the case of concrete substrates, determine when the concrete was installed.


• In the case of concrete substrates on or below grade, determine whether or not an effective moisture vapour barrier has been installed.


• In the case of wood substrates, determine the moisture content of the substrate materials (joists, sheathing, etc.) delivered to the site, if they were protected during site storage or subjected to moisture after installation (e.g. rain), when the substrates were protected from the elements (building enclosed), and how long and at what temperatures they have been left to dry.


• In the case of wood substrates on floor framing systems over a crawl space, determine if the space below is in accordance with requirements noted in Part A10 - Acceptable Conditions.

.02    When test results indicate that the moisture level of a substrate exceeds that specified by a floor covering material manufacturer, sufficient time will be allowed for the                     substrate to dry to an acceptable level and for concrete to fully cure. Re-testing will be performed before the installation of any material is attempted.

.03    When test results indicate that the moisture level of existing (fully cured) concrete substrates exceeds the maximum amount tolerated by the selected flooring product           manufacturers, it is recommended that an experienced water proofing / sealing contractor rectify the moisture problems at the Owner's expense, before any type of flooring is installed.

Special note: It is important to recognize that moisture tests of any substrate indicate the amount of moisture at the time of the test only and they should not be             used to ascertain the long-term moisture emission rating of any substrate surface.

5 • MOISTURE INDICATION TESTING VERSUS MOISTURE TESTING

.01    Electronic moisture meters measure the moisture content in a concrete slab, most commonly in terms of percentages. Most electronic moisture meters take readings from the  surface, while some probe into the slab. The moisture content of a slab indicates the degree of saturation, but not the vapour emission rate that is occurring. The NFCA  requires tests that indicate the quantity of moisture passing through a concrete slab, and for this reason does not accept tests that simply indicate the presence of moisture (i.e. moisture indicator tests).

.02    Moisture Indicator Testing:

• Electronic Moisture Detection Meters: There are a number of electronic pin and pin-less type moisture detection meters available to read surface and internal moisture levels in both concrete and wood substrates. Utilizing such meters must be in strict compliance with the manufacturers recommendations in order to obtain moisture levels present (at the time of testing). The meters must be precisely calibrated to suit the substrate to be tested. The type and length of pin or electrodes used shall also suit the type of substrate to be tested. Some of these metering devices may be limited as to the depth or degree of penetration into the substrate to obtain moisture readings.
  
  
• Electronic moisture meters measure content of moisture in a concrete slab, most commonly in terms of percentages. Most electronic moisture meters take readings from the surface, while some probe into the slab. The moisture content of a slab indicates the degree of saturation, but not the vapour emission rate that is occurring. NFCA recommends tests that indicate the quantity of moisture passing through a concrete slab, and for this reason does not recommend using electronic moisture meters.

 

• ASTM F2659 Standard Guide for Preliminary Evaluation of Comparative Moisture Condition of Concrete, Gypsum Cement and Other Floor Slabs and Screeds Using a Non-Destructive Electronic Moisture Meter

.03    Moisture Detection Testing: The following testing measures are acceptable to NFCA in regard to measuring the vapour emission rate that is occurring.

• ASTM D4263, Standard Test Method for Indicating Moisture in Concrete by the Plastic Sheet Method: This simple mat test method for concrete substrates involves taping a dense mat / plastic sheet to the concrete substrate surface to detect the presence of capillary moisture. The test shall be conducted in accordance with the requirements of this standard to obtain qualitative moisture results by visual observation after removing the mat covering. The placement time required should be no less than 60 hours.
• ASTM E96, Standard Test Methods for Water Vapour Transmission of Materials: These test methods cover the determination of water vapour transmission (WVT) of materials through which the passage of water vapour may be of importance, such as polyethylene, other sheet materials, fibreboards and other wood products, and plastics. Two basic methods, the Desiccant Method and the Water Method, are provided for the measurement of permeance, and two variations include service conditions with one side wetted and service conditions with low humidity on one side and high humidity on the other. Agreement should not be expected between results obtained by different methods. A method should be selected which more nearly approaches the conditions of use.
• ASTM E1907, Standard Practices for determining Moisture-Related Acceptability of Concrete Floors to Receive Moisture-Sensitive Finishes. These practices include both quantitative and qualitative procedures used to determine the amount of water or water vapour present in or emitting from concrete slabs and criteria for evaluating the moisture-related acceptability of concrete slabs to receive moisture-sensitive manufactured finish products, including certain types of resilient flooring, carpet, carpet tiles, and wood flooring, as well as related adhesives.
• Although coatings, films, and paints are not specifically intended to be included in the category of "moisture sensitive finishes" the procedures included in these practices may be useful for evaluating the moisture-related acceptability of concrete slabs for such finishes.
  
  These practices do not cover the adequacy of a concrete substrate to perform its structural requirements, do not include procedures to determine the presence of non-moisture related impediments to the application of finishes, and do not supersede the specific instructions or recommendations of manufacturers for their flooring finishes.
  
  
  • Hygrometer Moisture Test: This test method for concrete and wood substrates uses a hygrometer testing device to ascertain the percentage of humidity being omitted from a substrate surface. Readings of less than 85% R.H. (Relative Humidity) are considered acceptable. Hygrometers may also read the relative humidity, dew point and temperature of the work place environment.
  • Core / Slab Moisture Determination Test: This destructive test method for concrete substrates is generally conducted by certified lab technicians, and involves removing a piece of the concrete slab that is then weighed, oven dried and then re-weighed. Results of 3% (weight difference) or less are considered acceptable.
• ASTM F1869, Standard Test Method for Measuring Moisture Vapour Emission Rate of Concrete Subfloor Using Anhydrous Calcium Chloride: This desiccant test method for testing concrete has come into question in recent years, yet is still recommended by some manufacturers to determine the MVER (Moisture Vapour Emission Rate) from below-grade, on-grade, and above-grade (suspended) concrete floors. Particularly useful when the sub-floor to be tested has an in-floor heating system, making a drill type test such as ASTM F-2170 impracticle or too risky. The test involves placing anhydrous calcium chloride crystals on a concrete substrate and sealing them under a moisture impervious cover for a specific time period to determine the amount of moisture absorbed into the crystals. The crystals must be precisely weighed before and after the test and the difference in weight determined. Moisture test kits are available for this purpose from most flooring supply and installation distributors. The test must be carefully conducted in strict accordance with the test kit manufacturer's detailed instructions. Inaccurate results can occur for a variety of reasons which has led many manufacturers to require both the Calcium Chloride and In-situ probe test to be taken to ensure acceptable moisture levels. Because the test for emission rate requires a minimum of 60 hours to conduct, enough time must be allotted to conduct the test before the installation of any flooring materials.
• This test was initially developed by the Rubber Manufacturer's Association (RMA) and has been referred to as the RMA Test. It is has also been referred to as the Moisture Dome Test.
  
  
• ASTM F2170, Standard Test Method for Determining Relative humidity in Concrete Floor Slabs Using in situ Probes: This drilled probe test method is highly recommended by NFCA as one of the most definitive tests to determine the percent of relative humidity in concrete slabs. The test consists of drilling a hole into the concrete, inserting a sleeve and humidity probe to measure the humidity over a period of time

.04    Acceptable Moisture Emission Levels: 

• Moisture emission rates are expressed in either kg/100 m² or lbs/1000 ft² over a 24 hour period.


• As a general guideline, an emission rate of 1.4 kg/100m² (3 lbs/1000 ft²) or less is considered acceptable for most floor coverings. However, and unless otherwise permitted by a flooring product manufacturer, the following maximum moisture emission levels over a 24 hour period are permissible for the following floor coverings types:
  
  
  • Homogenous Resilient Sheet and Tile Flooring: 1.4 kg/m² (3.0 lbs/1000 ft²).
  • Non-Impervious Backed Resilient Flooring: 2.3 kg/m² (5.0 lbs/1000 ft²).
  • Porous Backed Carpet: 2.3 kg/m² (5.0 lbs/1000 ft²).
  • Impervious Backed Carpet: 1.4 kg/m² (3.0 lbs/1000 ft²).
  • Hardwood Flooring: 2.1 kg/m² (4.5 lbs/1000 ft²).
  • Laminate Flooring: 1.4 kg/m² (3.0 lbs/1000 ft²).


• Carpet with porous backings can usually be installed successfully where the emission rate is between 1.4 to 2.3 kg (3 to 5 lbs), however the risk of moisture related problems increases.


• All moisture emission ratings must be verified before the installation of any flooring materials.

6 • ALKALINITY TESTING

.01    Alkali Detection Testing (Litmus Paper Test): This simple test method for concrete substrates involves placing distilled (mineral free) water on the concrete substrate          surface and then placing a strip of litmus paper into the distilled water. The change in colour of the litmus paper indicates the pH rating of the distilled water that has reacted to  any substances present on the concrete substrate. A colour bar scale normally supplied with the litmus paper will allow the tester to determine the pH level of the affected water by matching the affected litmus paper to the scale.

.02    Most calcium chloride test kits now contain alkali testing material. To determine the alkalinity level of the concrete substrate the following steps must be taken:

• Check with the adhesive and flooring covering manufacturer for recommended testing and corrective procedures and for acceptable results.


• Place strips of litmus paper on the slab surface and submerge them in distilled (mineral free) water. Note that this test is highly recommended when using water-based adhesives.

.03    The allowable pH range for the installation of most flooring is normally between 5 and 9.

.04    The pH rating of new concrete will be between 12 and 13. This should lower with drying. In the presence of a continuous water source however, alkali may continue to be     drawn to the surface of concrete. A pH range between 7 to 9 may be deemed acceptable for some floor covering materials. A reading above 9 will generally require corrective measures.

.05    When test results indicate that the alkalinity level of new or existing concrete substrates exceed that specified by a floor covering material manufacturer, corrective measures shall be undertaken to ensure that the alkalinity level is brought to an acceptable level. Re-testing shall be performed before the installation of any floor covering material is attempted. If testing continues to show a high alkalinity rating the cause must be determined.

.06    Rinsing with clear water (or soda water) is a good way to lower alkalinity, but it cannot prevent the future deposit of alkali on concrete surfaces. While an acid wash may have been traditionally used to neutralize alkalinity, it is important to remember that acids can leave a residue that can be as detrimental to the installation of any flooring material as the alkali itself.

.07    It is important to recognize that alkalinity tests of concrete substrates indicate the amount of alkalinity at the time of the test only and they should not be used to               ascertain the long-term alkalinity rating of any substrate surface.

Special note: Whatever test method or metering device is used for moisture and alkalinity testing, the flooring manufacturer shall be consulted in regard to the                 acceptance of the specific test readings / results and the flooring supplier informed before any flooring is ordered.

7 • TESTING ERRORS

.01    All tests must be conducted in strict compliance with recognized testing procedures using personnel thoroughly competent in conducting such testing.

.02    To ensure accurate readings, all testing equipment shall be checked and calibrated before use in accordance with manufacturers requirements.

.03    Individuals conducting the tests must be aware of all circumstances at the Work site that could potentially influence the test results.

.04    Individuals interpreting the test results shall have sufficient experience to validate the test results.

.05    Misinterpretations of test results may occur if:

• substrate surfaces are sealed or coated (e.g., concrete sealers).


• metal reinforcement is too close to the surface.


• the humidity or temperature is excessively high or low, etc.

8 • MAT BOND (PULL) TEST 

.01    Bond tests are conducted to determine if the flooring adhesive will bond to the substrate. This is to ensure that such surfaces are free from any surface treatment (sealer and curing agents, parting compounds, etc.) or condition (old adhesive, dust inhibitors, oil, grease, paint, varnish or any other finish that is detrimental to adhesive bond.

.02    Such tests are performed by using minimum 600 mm (24") square pieces of the specified flooring randomly spaced throughout the area to be covered and by adhering them to the substrate using specified adhesives recommended by the manufacturer all in accordance with the adhesive and flooring manufacturer's installation instructions. The edges of the samples should be taped to prevent edge drying of the adhesive.

.03    The adhered test samples must be rolled thoroughly and be allowed to set for a minimum of 72 hours before testing for bond strength.

.04    The test samples are then either cut into 50 mm (2") strips or left intact and then pried loose from the substrate surface. If they are securely bonded it can be concluded that the surface is sufficiently clean and acceptable for further application of flooring materials. If an unusual amount of force is required, it can be concluded that the material is   "securely bonded" to the substrate.

Mat Bond test failed

Mat Bond test passed

Mat Bond test failed. Inadequate adhesive transfer  to the back of the flooring product

​.05    If sample material is easily peeled off, then the substrate surface is unsatisfactory for adhesive bonding and remedial action must be undertaken to address the surface      condition and remove whatever material or condition is inhibiting bonding.

.06  Refer to ASTM F3311 Standard Practice for Mat Bond Evaluation of Performance and Compatibility for Resilient Flooring System Components Prior to Installation. 

.07  General bonding of flooring:  The flooring being tested should be well bonded to the subfloor (i.e., no bond loss, de-bonding, bubbles) and not installed over subfloors with moving joints.

9 • ACCEPTANCE OF SUBSTRATE SURFACES

.01    The maximum moisture and alkalinity levels allowed for any floor covering material (including adhesive, resilient flooring, cushion and carpet) shall not exceed those specified by the material manufacturer.

.02    Since some floor covering products are less tolerant of moisture and alkali than others, the individual floor covering product manufacturer must be consulted to determine the acceptable moisture and alkali ratings for their specific products. If such levels exceed those specified by the manufacturer of any material being installed, the installation must not be attempted.

.03 It is the responsibility of the floor covering contractor to verify moisture test results.

10 • SUBSTRATE SURFACE WATER ABSORPTION (POROSITY) TESTING

.01   Substrate surfaces must demonstrate an acceptable water absorption rate prior to application of products that are designed to bond to a surface (adhesives, Primers, Hydraulic Cement Underlayment).

.02    Concrete surface density or concrete surface contaminants (paint, sealers, curing agents etc.), can interfere with a products ability to bond. Also, moisture tests that measure concrete surface vapor emissions, such as the Anhydrous Calcium Chloride Test (ASTM F-1869) can be negatively effected.

.03    Installing flooring products over low or non-absorptive (sometimes referred to as “non-porous”) substrates such as densely machine-troweled concrete, mature and well-hydrated concrete, existing resilient flooring, polymer terrazzo and others may require adjustments to the surface preparation method or product selection to ensure a successful installation.

.04    Surfaces that exhibit immediate absorption (excessive porosity), are dusty, or have varying degrees of absorption may require priming or additional surface preparation prior installation of any adhesives, glue down floor coverings or related products such as Hydraulic Cement Underlayment.

.05    Substrates that evidence no absorption may indicate the presence of a contaminant that may negatively impact proper adhesion. In such cases, bond tests performed in accordance with the particular manufacturer’s established guidelines are strongly recommended.

.06    Some surfaces such as concrete can become denser and less porous/less absorptive over time as the material continues to gain strength and densify. The results obtained reflect only the conditions of the substrate at the time and location of the test(s).

.07    Consult the manufacturer of the specified product prior to application. Where Resilient Flooring is specified, conduct a porosity test where applicable in accordance with ASTM F3191 Standard Practice for Determination of Substrate Water Absorption (Porosity) for Substrates to Recieve Resilient Flooring.
​

11 • SUBSTRATE SURFACE TEMPERATURE TESTING

​01.    Surface temperatures must be confirmed acceptable to Hydraulic Cement Underlayment, adhesive, and floor covering manufacturers recommendations. Infra-Red Lazer thermometers are an effective way of testing for surface temperature. 
​

12 • CONCRETE SURFACE PROFILE (CSP)

​​.01     Substrate surface must exhibit an acceptable Concrete Surface Profile (CSP) prior to placement of any toppings or floor covering products.

.02.    Overly smooth surfaces can prevent an acceptable bond for both Hydraulic Cement Underlayment (self levellers) and many flooring adhesive products.

.03     Onsite comparison testing using physical swatches should be conducted to confirm the surface of the provided concrete is acceptable and meets the Hydraulic Cement Underlayment, adhesive and/or floor covering product manufacturers recommendations prior to installation of any products. Charts and physical, molded swatches (samples) demonstrating various levels of CSP are available through the International Concrete Repair Institute (www.icri.org).

13 • TESTING FOR DELAMINATING OR LOOSE SUBSTRATE MATERIAL

.01 A chain-drag method (1/4" gauge steel chain) can be used to check for delaminated, loose and or hollow areas.

Note: Existing subfloors/substrates should be "sound and stable" without the risk of debonding or delamination of the base concrete or any added leveller, or skimcoat that could affect the floor covering and its performance.  Furthemore, during early renovation construction, if the subfloor/substrate is found to be sound and stable (i.e. using visual observations, sounding bar, hammer strikes, chain drag, chipping tests, shot blasting, and/or other evaluation methods) then it should be protected from static and dynamic loads as well as accidental impact damage during on-going construction.  This may require the use of hardboard or plywood of sufficient thickness to protect the subfloor/substrate from potential fracturing, cracking, delamination, and/or shear damage. 

"Sound" would refer to the subfloor/substrate being of sufficient integrity, hardness, rigidity, and internal cohesive (i.e. not powdery or flaking) strength to withstand future use activities. 

"Stable" would refer to the subfloor/substrate's ability to perform without any potential adverse reaction causing delamination, fracturing, or cracking while the floor covering is in service. ​

.02  A suitable, 1/2" x 4' long solid steel pipe can also be used to identify delaminated or loose substrate material (Video 1)

Video 1

.03 Other methods include hammer strikes, chipping tests, shot blasting.

14 • BEST PRACTICES FOR VISUALIZATION OF ACCEPTABLE SUBSTRATES FOR FLOORCOVERINGS AND COATINGS

UNDER REVIEW UNTIL AUGUST 1st 2022

1. Introduction
2. Definitions
3. Structural Concrete Tolerances (Qualtitative)
4. Floorcovering tolerances (Qualitative)
5. Mapping Qualitative Floor Tolerances using a variety of Straightedge Tools
6. Construction Sequence and Trade Responsibilities
7. Tools for surveying, mapping, recording concrete surface topography
8. Who is Responsible for Maintaining Specified Concrete Slab Flatness for Duration of Construction?

.01 Introduction

Floor flatness and regularity needs to be correctly specified and properly monitored during construction so that departures from a theoretically perfectly flat plane are limited to the extent appropriate to the planned types of the floorcoverings and coatings specified for the project, and the intended occupancy type of the project.

• A resilient flooring installation for a hospital operating room or diagnostic imaging facility will require tighter control on surface regularity than a similar resilient flooring installation for a commercial building or office facility.
• Inappropriate surface regularity resulting from incorrect specification or as a result of a construction deficiency may result in a potential trip‑and‑fall hazard, differential wear and early replacement of flooring materials, uneven gloss or appearance, discolorations, loss of infection control and increased maintenance.

Acceptable concrete slab flatness for installation of floorcoverings has no nationally accepted standard for taking measurements for establishing compliance with manufacturers’ stated flatness profile requirement. The traditional approach uses the structural concrete tolerance measurement, which specifies acceptable gap under an unlevelled straightedge to determine relative flatness of the concrete surface, and that frequently leads to conflict between the trades that finish concrete and the trades that install floorcoverings.

Visualization and verification of concrete slab flatness is essential to confirm that the floorcovering manufacturers’ flatness requirement is met prior to installation start up. An effective measurement practice also identifies differences in surface elevation that can affect final installation as follows:

• Excessively high ridges and mounds in the floor cause maintenance issues resulting from surface wear and diminish the service life for the installed floorcovering.
• The height differential can cause visual tripping hazards for people with low visual acuity or depth perception, particularly when spaces between high and low points are less than 2 metres apart.
• Height differential causes runoff and gapping when installing floorcovering products; the larger the floorcovering module and change in surface elevation, the greater the issue becomes making repairs extremely difficult or impossible and causes unacceptable installation appearance.
• The height differential can also cause dead spots in heavily trafficked areas, causing pedestrians to experience a change in footfall experience, causing the foot sole to hit the floor sooner or miss the floor when a depression is deeper than expected, and also contributes to tripping.
• Dead spots can also contribute to injuries in professional and recreational athletes, or change the rebound behavior of balls and gymnastic manoeuvres that affect the direction of travel and consequential outcomes of the sporting activities.

Achieving successful concrete slab flatness is dependent on two different trades that measure surface tolerance based on different performance expectations, and that are seldom sitting in the same room when decisions for acceptable project requirements are being finalized.

• Concrete placing and finishing are governed by structural tolerances that are based on reasonable safety and usage criteria that determine whether a building frame can withstand applied loads without excessive deformation or collapse and maintain occupant safety.
• Floorcovering installation is governed by architectural tolerances that are based on reasonable appearance and functional criteria that determine whether the user of the building can experience the space without injury or impediment to movement, and maintain occupant safety.

.02 Definitions

• Flatness (surface flatness or surface regularity): refers to how uniformly flat a substrate surface is in relation to any undulations, waviness or bumpiness it has in comparison to a straight line or flat plane. Example: A ramp is flat but not level. Flatness is the 3D version of surface straightness. 
• Level: Absence of deviation from the horizontal plane. A horizontal plane with no tilt or slope. Level is compared to the tilt or slope of the substrate. Example: Parallel with the horizon. A table or countertop. Calm water in a swimming pool or lake. 
• Smooth: Refers to texture of the substrate surface, having an even and regular surface or consistency without projections, bumps, indentations or other irregularities. Free of defects in the surface that could telegraph/profile through or affect the bond, performance, or appearance of the floor covering or coating. Examples: A skateboard park is smooth, but not flat or level. A window is smooth and flat, but not level. A skating rink is smooth, flat, and level. 
• Deflection (NFCA): The displacement or deformation of a material from its original position due to the effects of an applied load. Example of Deflection – The use of a trampoline. A trampoline’s surface deforms due to the effects of someone standing (dead weight) or jumping (live weight) on it. 
• Datum: A datum is a theoretical exact plane, axis (line), or point location that dimensional tolerances are referenced to. 
• Subfloor, n—that structural layer intended to provide support for design loadings which may receive resilient floor coverings directly, if the surface is appropriate, or indirectly via an underlayment if its surface is not suitable.  
• Substrate, n—the underlying support surface upon which the flooring is installed.
• Straightedge: A rigid, metal, flat, light weight, long-wearing rectangular bar of fixed length, typically 6’ (2m), 8’ (2.4m) or 10’ (3m), with a smooth and even straight edge base designed for measuring flatness of substrates in preparation for flooring or coatings and also for measuring flatness in post-installations of flooring or coatings. 
• Dimensional tolerance: This refers to the defined length or distance that flatness deviations must be tested within, typically 6’ (2m) or 10’ (3m). 
• Flatness tolerance: The flatness tolerance references two parallel (virtual?) planes, parallel with the substrate surface that define a zone where the floor covering or coating must lie. The flatness tolerance is the maximum deviation (gap space) that is acceptable between the two planes for the installation of flooring or coatings. 

Need a photo showing two parallel lines in situation

• Tolerance zone/level: In straightedge measurements, the tolerance zone starts between two lines and progresses to two sets of parallel planes where the entire referenced surface deviations must lie. 
  
• Deviation: The gap space between the underside of the straightedge and the top of the substrate, flooring or coating. 
  
• Gauging/Measurement: Flatness deviations (gap spaces) are measured using a height gauge (ruler) or angular gauge (taper gauge) in combination with a straightedge placed over the substrate, floor covering, or coated surface. 
  
• Gauge holder: A holding device to hold a ruler upright against the straightedge while measuring the maximum deviation. 
  
• Other Key words/phrases: virtual planes, uniformly flat, micro-heights, flatness error, flatness value, specified area, straightness/flatness, tightening tolerance, flatness control, prescribed distance, specified tolerance, …) 

.03 Structural Concrete Tolerances (Quantitative)

The concrete finishing trade use a quantitative tolerance measurement described by ASTM E1155, Test Method for DeterminingFF Floor Flatness and FL Floor Levelness, which limits results to defined measurement paths and does not include results for constructions joints, openings in the slab, 2’ from room perimeter walls and support columns. The results are also only relevant when measured within 3 days of concrete placement, and before removal of shoring and formwork.

• The structural concrete standard does not account for subsequent deformations to the flatness as the slab shrinks and settles after acceptance of the concrete work.
• The structural concrete standard accounts for defined paths of measurement; and does not address the overall surface flatness, meaning that the flatness can vary significantly if the same measurements are offset from the defined lines of measurement.
• The structural concrete standard also does not address natural changes to the concrete that occur during the intervening weeks, months, and years from when the structural concrete measurements were made and found acceptable.
• The structural concrete tolerances do not address the quality aspects of surface flatness that the floorcovering trades are required to install their products in accordance with manufacturers’ required flatness profiles.

Structural concrete can also be measured using a different quantitative tolerance measurement that maps the surface undulation of a slab using ASTM E1486, Test Method for Determining Floor Tolerances Using Waviness, Wheel Path and Levelness Criteria. This method addresses some of the quality issues that affect installation of floorcoverings, but is also limited in its effective use by the same concerns as the ASTM E1155 test method as follows:

• Measurement within 3 days of concrete placement, which does not account for natural changes that occur subsequent to when after the measurement was accepted: and
• Paths of measurements that do not address surface imperfections that occur off the defined line or that have a noticeable height difference and waviness that occur less than 300 mm apart.

.04 Floorcovering Concrete Tolerances (Qualitative)

​Both tests described above are a vast improvement from pre-1970’s measurements that relied on a single random placement of a straightedge, and which was most often placed or manipulated to show a specific advantage to more favourable results. Concrete finishing has improved significantly since these tests and testing equipment were developed; and given the absence of a test associated with quality, have also been used to define the requirements for installation of floorcoverings.
Both test methods described above are referenced in ASTM F710, Standard Practice for Preparing Concrete Floors to Receive Resilient Flooring; and as stated in the standard, the ASTM E1155 and ASTM E1486 methods are recommended in the absence of a specific flatness tests addressing acceptable flatness for resilient flooring.

• The floorcovering standard states that specifications for slabs receiving resilient flooring should address issues associated with small‑scale smoothness as a qualitative requirement.
• The floorcovering standard advises that specifying an acceptable flatness for new concrete placement be based on a comparison measurement of a similar satisfactory existing floor.
• The floorcovering standard also includes recommendations for surface preparation and remedial measures to correct out‑of‑tolerance slabs by grinding, planing or installation of underlayments and toppings.

ASTM F710 is also applicable to other floorcoverings including carpet, carpet tile, ceramic and porcelain tile, wood flooring, coatings and films, and paint coverings. The standard practice is not limited to only resilient flooring sheet and tile products.

.05 Mapping Qualitative Floor Tolerances using a Variety of Straightedge Tools

​Mapping the floor area allows everyone associated with the project team to visualize the quality of the surface profile and determine whether a concrete slab is acceptable for installation of floorcovering materials, or whether any remediation is required before installation can start. Mapping can show several different conditions that that affect installation, and other conditions that may affect final use of the spaces being finished.

• Level but Not Flat: Will require correction of the surface to bring flatness tolerance to acceptable performance required by floorcovering manufacturers.
• Flat but Not Level: Flatness tolerance meets floorcovering manufacturers performance requirements, but may affect use of the room when the amount of tilt affects movement of objects in the room. Image 1e

Image 1

• Flat but Not Smooth: Flatness tolerance meets floorcovering manufacturers performance requirements, but surface texture is uneven, or contains projections, hollows, bumps and other irregularities that telegraph through to the surface of the floorcovering material, or impair bond, performance and appearance of the floorcovering or coating.

Image 2

• Smooth but Not Flat: Flatness tolerance is not met. Surface profile is acceptable. Image 3 and 4

Image 3

Image 4

• Level but Not Smooth: Surface remediation is required to reach acceptable Concrete Surface Profile (CSP) and a consistent surface that will not telegraph unacceptable irregularities to the floor covering surface. Image 5 and 6

Image 5

Image 6

• Level, Flat, and Smooth: The best outcome, when concrete placing and finishing operations are coordinated with floorcovering installation requirements, and proper curing and protection regimes are implemented for the project. Image 7 

Image 7

• Multiple, Short, Bumpy Surface: The concrete surface is flat and level but not smooth. The space will require flooding with Hydraulic Cement Underlayment to meet the  floor covering manufacturers substrate requirements. Image 8

Image 8

• An Extended Bump: Long extended areas of the concrete slab are high and will require a combination of grinding and pouring of HCU. Structural characteristics of the slab must be considered before removing thickness or adding cementitious underlayment & weight. Image 9

Image 9

• Flat, then Declines: Long runs of flat and level slab then a sudden decline. Image 10

Image 10

Straightedge measurements form the basis for most surface flatness (surface regularity) tests regardless of the building component, and can also be used to determine changes in surface levels (tilt). There is no single preferred methodology used by floorcovering installers. Selection of a measurement method should be based on the knowledge and skills of the floorcovering installer, the intended usage of the floor area, size and complexity of the project and the types of floorcovering materials being installed:

• Floorcoverings are most dependent on the surface smoothness flatness (undulation) and perform best when the surface meets manufacturers specified tolerance. Image 11
• Floorcoverings can be affected by the tilt of floor surfaces, but are less dependent on intentional levelness for end‑use performance.

Image 11

Visualizing and mapping concrete flatness can use a variety of straightedge tools, and are dependent on the familiarity of the floorcovering trades for the equipment being used. Measurements must be made immediately before installation of floorcovering materials and are made within unobstructed areas. The type of straightedge test is dependent on the size of the space being measured, and must provide analysis of the overall floor area rather than spot or linear measurements.

1. Substrate  tolerances are currently being measured using a flatness and levelness procedure used for measuring freshly placed concrete based on ASTM E1155, and may provide results that are not consistent with current site conditions. The ASTM E1155 is a quantitative measurement that does not address the qualitative approach to determining the acceptance of the substrate condition for various floorcovering materials.
2. Qualitative measurements can be made using a 2.4 metre (6’) or 3.0 metre (10’) straightedge being moved across the surface of the floor to assess the amount of unevenness of the surface.
   • The method is applied by continuously moving the straightedge across the surface and provides the installer with a visualization of the surface topography:
     • Gap can be measured under the straightedge, or at the tip where the straightedge rests on a mound or ridge.
     • The straightedge provides a map of contours, bumps, ridges and hollows that the installer can compare to a different existing substrate that had similar satisfactory installation result.
     • The straight edge also provides identification of areas that cannot be accommodated by thin mortar materials typically used by installers for surface preparation.
     • This methodology is not intended to be repeatable or quantifiable – it is intended to provide the installer with a “feel” for the suitability of the substrate and to help identify surface deficiencies that may cause rejection of finished work.
   • Alternatively, the floorcovering installer may use a stringline suspended over the floor, with measurements made to the substrate to build up mapping data at a 1.0 metre or 1.2 metre offset grid, or use a laser scanner with sufficient resolution to show elevation variations smaller than 3 mm, or other method that can provide a reasonable interpretation of the surface geometry (topography) of the substrate.
     • Results from straightedge can be represented by chalk marks showing high points discovered by the straightedge.
     • Results from stringline can be presented as a grid of numbers showing areas of concern, and can also be entered into software to translate into a topographical map.
     • Results from laser scan can be shown as a 3D heat map or topographical map using contour lines.
   • The qualitative measurements should be made by the installer, who is best able to provide an opinion on the suitability of the surface for installation of the specified floorcovering products. 
     
     • Measurements should be witnessed by the Constructor, the Consultant and the Owner to build a consensus of acceptable existing substrate, and substrates that may require additional correction by the Constructor for repairs that are in excess of acceptable tolerances for installation of specified floorcovering materials.
       
     • This approach should minimize the number of corrections to the existing substrate profile, and identify only those areas that are significantly out‑of‑tolerance within areas of concern.
       
     • The Owner should be the entity accepting the final substrate condition, after consideration of recommendations by the Consultant, the Installer and the Constructor.

.06 Construction Sequence and Trade Responsibilities

Who does what and when does the activity occur? In the past, concrete floors that have appropriate flatness tolerances required input between 2 vastly different trades (Concrete and Floorcoverings) that perform their work many months or years apart. This approach has not been successful, because it places inappropriate risk on the trades associated with the work without accounting for the limitations of what is achievable by the two trades.

​Success is dependent on aligning skillsets of the two trades, recognizing the limitations of each trade in achieving appropriate flatness tolerances, and recognizing that achieving appropriate flatness tolerances requires a high degree of cooperation, planning and potentially correction. A balanced approach to construction risk involves the consultant, the constructor, the two trades involved with the work and the project owner, and should also include the manufacturer and supplier.

1. Manufacturer: The manufacturer is responsible for producing a floorcovering materials that will perform as advertised, that will perform based on the installation conditions and usage expectations of the project, and will perform when installed in accordance with their written instructions. 
   1. The manufacturer is also responsible for informing the consultant, the constructor and the flooring installation trade of conditions that affect installation of their products, and providing technical support and recommendations when jobsite conditions differ from standard installation conditions described in their written installation instructions.
   2. The manufacturer may also contribute to supplier competencies through training programs and local resources to monitor product sales and obtain confirmation that materials are being represented based on the manufacturer’s written product literature.
2. Suppliers: The distributors, wholesalers, importers and resellers that receives product from the manufacturer and subsequently distributes floorcovering materials to the flooring installation trade is responsible for appropriate storage (ventilated, climate controlled, dry) conditions, and to confirm that products sold to the installer and delivered to the jobsite are appropriate for the stated use, and that delivery conditions meet manufacturer’s written installation requirements.
3. Consultant: The architect, interior designer or specifier is responsible for identifying performance, installation and environmental tolerances appropriate to the floorcoverings being specified. This requires the consultant to make themselves aware of the products they are selecting for the project, and developing a specification that coordinates the work required to describe project outcomes:
   1. The specification describes the work results for the project; it does not tell the constructor and trades how to do their work, and/ it? uses words that describe what is required to achieve an acceptable installation.
   2. The consultant also provides contract administration services, reviews the work and advises the owner about work that is compliant with the contract, and makes recommendations to the owner for payment of work completed in accordance with the specifications.
   3. The consultant is responsible for determining that the contract is completed in accordance with the specifications, that the work complies with the building code, and that the completed construction is usable for its intended purpose.
   4. Consultant considers relative risk within project budgets and notifies the owner of any cost concerns, and establishes a cash allowance for adjustment to floor profile or moisture control when appropriate.
4. Constructor: The general contractor, construction manager or design builder is responsible for coordinating the work, and providing jobsite conditions that are capable of meeting the specified installation and environmental tolerances identified within the consultant’s specifications, and performing construction activities that do not form a part of the concrete finishing and floorcovering trades defined scope‑of‑work. The constructor is responsible for the following:
   1. Provision of acceptable substrate surfaces that meet the tolerance requirements of the scheduled floorcovering and related products.
   2. Setting up coordination meetings between concrete and flooring trades, so that both trades can describe the limitations and expectations of their individual contributions to the project.
   3. Setting up conditions that are favourable to the placement, finishing and curing of concrete that will meet specified performance and installation tolerances, and maintaining environmental conditions that maintain those tolerances for the duration of construction.
   4. Providing temporary facilities and starting permanent building ventilation systems (humidity control, heating/cooling, protection from wetting)  that allow for drying of concrete slabs, and maintains surface conditions required for installation of floorcovering materials.
   5. Providing third‑party slab moisture testing and measurements of surface flatness after acceptance of compliant concrete placement and finishing to monitor and verify that changes to slab moisture content, alkalinity and flatness are within floorcovering manufacturer’s acceptable tolerances.
   6. Protect concrete slabs from wetting (snow, rain, water leaks, condensation), contamination from trades (oil, chemical, debris), and maintaining appropriate heating and ventilation to aid in drying of slabs ready for installation of floorcovering materials.
   7. Removing applied coatings and treatments (curing compounds, hardening compounds, surface sealers, permanent markers), surface laitance and other contaminants that have potential to affect adhesion of floorcoverings to concrete slab, and mechanical surface preparation for surfaces that have received a hard trowel (burnished/burned) concrete finish.
   8. Making adjustments or corrections to concrete slabs such as; bump grinding, surface profiling, moisture or chemical mitigation, and repairing damage caused by other trades before turning slabs over to flooring installation trades; concrete will continue to change shape and deflect during the construction period, which may affect surface tolerances measured within 3 days of completing concrete work and rendering them unacceptable to floorcovering manufacturer’s written installation requirements.
   9. Providing adequate notification to flooring installation trade to permit timely ordering of floorcovering materials and review of site conditions that may affect installation of the products when they are delivered to the jobsite.
   10. A detailed listing of constructor responsibilities is contained in the NFCA Floorcovering Reference Manual.
5. Concrete Trade: The concrete trade is responsible for coordinating concrete mix design, scheduling, and placing of concrete, finishing concrete surfaces to meet surface tolerances and profiles stated in the specifications. The concrete trade is also responsible for coordinating with other trades affected by their work, and make any repairs caused by out‑of‑tolerance observations based on measurements made within 3 days of concrete placement.
6. Floorcovering Trade: The floorcovering trade is responsible for minor surface preparation, limited to 2 to 3 mm of trowel applied mortars (often referred to as a skim or scratch coat) to make final correction to the provided, concrete slabs (typically a straightedge tolerance of 4.5 mm in 3 metres (3/16” over 10’). See General Requirements section of A12 Substrate Preparation.
   1. The Constructor shall perform surface tests to confirm the scheduled floorcovering manufacturer's flatness tolerances have been met prior to turning the substrate over to the floorcovering installation trade.
   2. Flooring installation trade will also make qualitative tests to concrete substrates before installation of floorcovering materials as described in the NFCA Floor Covering Reference Manual, to confirm that slabs turned over to them meet floorcovering manufacturer’s written installation requirements.
   3. Moisture, alkalinity and surface flatness testing are performed by the constructor using a third‑party testing agency and are qualitative, these test results must be made available to the flooring installation trade for review and acceptance before they start installing floorcovering materials.
   4. Floorcovering installer will perform testing to confirm acceptability of concrete slabs including mat bond tests, porosity and surface temperature testing, and will identify any concerns for delaminated or loose portions of the substrate, surface profile and surface flatness to the constructor for additional correction or adjustment before starting installation of floorcovering materials.

.07 Tools for surveying, mapping, recording concrete surface topography

1. Straightedge Level (Quantitative): Using a Using a gauge (either a graduated wedge or ruler) to measure the gap under the straightedge, and either a 3 metre or 2.4 metre long straightedge depending on the size of the room being measured.
   1. The straightedge is placed at a starting point (typically a corner of the space), and follows a defined grid pattern with gap measurements taken along the length of the free‑resting straightedge with two points in contact along the substrate.
   2. The maximum gap is measured and results that exceed the permissible tolerance required by the floorcovering manufacturers are noted on the floor plan indicating the mapping results.
   3. There are no minimum or maximum number of tests performed, the goal is to determine the overall quality of concrete slab flatness without bias or intent to hide or conceal deficiencies.
   4. Measurements are made with no limitations as to distance from walls, construction joints or openings within the floor area.
   5. All gap measurements must be adjusted to a smaller number when using a shorter straightedge; a pivoting or teetering measurement spanning a single high point is not permitted.

Image 12

Image 13

Note: Image 12 shows concrete slab curling between two set pours. The chalked area is about 3' in width.

Video 1

1. Straightedge Level (Qualitative): Using a gauge (either a graduated wedge or ruler) to measure the gap under the straightedge, and either a 3 metre or 2.4 metre long straightedge depending on the size of the room being measured.
   1. The straightedge in an arc in front of the floorcovering installer to locate mounding or ridges in the floor surface that exceed the gap tolerance required by the floorcovering manufacturer.
   2. The installer rides the straightedge across the mound or ridge in a back and forth motion to map the extent of out‑of‑tolerance area, and marks the area with chalk to provide a visual guide to determine the extent of surface corrections required to bring the floor into an acceptable tolerance range. Video 2
   3. There are no minimum or maximum number of tests performed, the goal is to determine the overall quality of concrete slab flatness without bias or intent to hide or conceal deficiencies.
   4. Measurements are made with no limitations as to distance from walls, construction joints or openings within the floor area.
   5. All gap measurement must be adjusted to a smaller number when using a shorter straightedge, and can also be centred on the mound or ridge with measurement taken from the raised end of the straightedge with adjustment to a larger number – now you wish you remember high school trigonometry. 

Video 2

1. String Line Levels: Using a levelled string line with a height measured from an agreed upon datum point within the area being mapped (usually the centre of the room) and then measuring between the string line and the concrete slab surface at 1500 mm or 1200 mm intervals:
   1. Results are then recorded on a grid that shows relative height differences across the whole floor area.
   2. The grid can also be shown as a topographical map (Image 14) to quickly locate areas that are outside of the specified tolerance range and act as a visual aid to determine the extent of the height differentials (Image 15).
   3. There are no minimum or maximum number of tests performed, the goal is to determine the overall quality of concrete slab flatness without bias or intent to hide or conceal deficiencies.
   4. Measurements are made with no limitations as to distance from walls, construction joints or openings within the floor area.
   5. Surface visualization can be achieved using mapping software or by tracing elevation lines between similar point measurements depending on the size of the area being analyzed.

Image 14

Image 15

1. Profilometers (Image 15): Based on the grid measurement regime described for Straightedge (Quantitative) procedure described above, using digitizing equipment described in ASTM E1155 and ASTM E1486. The goal of this modified test is to provide a readout of the overall quality of the concrete slab flatness:
   1. There are no minimum or maximum number of tests performed, the goal is to determine the overall quality of concrete slab flatness without bias or intent to hide or conceal deficiencies.
   2. Measurements are made with no limitations as to distance from walls, construction joints or openings within the floor area.
   3. The equipment described within the reference standard can provide a digitized grid or topographical map similar to that provided by the Sting Line Level methodology described above.
   4. Used to concrete slab acceptability post pour and prior to floor covering installation start up.. 
   5. ASTM E1155 does not satisfy the measurement needs of the floor covering trade. The floor covering installer does not use this measurement method to verify surface flatness is acceptable..

Image 15

1. Laser Scanning: Laser scanning provides a point‑cloud analysis of the concrete slab and can provide a 3D surface map that allows for rapid identification of out‑of‑tolerance surface features, and typically has a resolution of 3 mm or less across the entire floor surface, which is within the minimum measurement requirements described by most floorcovering manufacturers.
   1. The number of tests performed are essentially infinite, and can determine the overall quality of large areas of concrete slab flatness with minimal involvement of personnel and time.
   2. Measurements are made with no limitations as to distance from walls, construction joints or openings within the floor area.
   3. Laser Scanning equipment can provide a fully interactive map, and allow for adjustments to the viewpoint and vertical scale to make visualization of the surface regularity easier to interpret.

Image 16

.08 Who is Responsible for Maintaining Specified Concrete Slab Flatness for Duration of Construction?

1. Remediation – some degree of remediation will always be required – the extent of remediation can be controlled with good construction quality management practices and coordination between trades.
2. Who does the remediation – weighting risk and responsibility --- concrete finishing has already been accepted, or corrections made to out‑of‑tolerance work and subsequently accepted.
3. Floorcovering installer is only responsible for smoothing and minor gap filling to a maximum of a millimetre or two based on the gauging thickness of the materials they use for floor preparation.
4. The constructor is responsible for holding the tolerance met by the concrete finishing trades and monitoring the condition of concrete during the course of construction for conditions that may affect the quality of the surface regularity (curing, temperature during construction, humidity conditions, concrete mix design) --- AND is responsible for remedial work to bring concrete slab surfaces to the specified floorcovering manufacturers’ tolerance.

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END OF SECTION