material allowing for the application of the tile? - … · proper slope to drains ... as rigid...

12 TileLetter v March 2004

s the use of ceramic tile andstone has continued to growsignificantly over the last

decade, the number of qualified peo-ple installing these products has notcome close to keeping up with thegrowth or demand. Therefore manyunqualified people end up installingceramic tile and stone, and there isn’tenough supervision of their work toensure successful installations. Thesolution is providing adequate installertraining emphasizing substrate prepa-ration and quality control. The major-ity of failures could be avoided if therewere adequate substrate preparationand adequate quality controls duringthe installation.

Most ceramic tile and stone (tile)failures are related to the lack of prop-er preparation. These installations areonly as good as the substrate to whichthey are applied, and the method andquality of installation used. So part ofthe substrate preparation is to deter-

mine whether a particular substrate isadequate for the intended use.

The substrate is the foundation ofthe installation. When this foundationis unsuitable for whatever reason, theproducts applied are automatically injeopardy. Thankfully, remedies existfor correcting substrate problems, butit is important to first evaluate the sub-strate and take any corrective action aspart of the substrate preparationprocess.

SUBSTRATE QUALITY AND SUITABILITY

Several key questions help qualifythe suitability of the substrate.Is the substrate made of a suitablematerial allowing for the applicationof the tile?

Concrete substrates are an excellentoption because they are very stable andare not significantly affected by expo-sure to moisture. There are limitationsto adhering to lightweight concrete, asit tends to have an unstable surface.

by Donato Pompo, CTC, CSI, CDT, MBA


Remedies for this situation exist. Onemethod is to first apply a thin coat of alatex modified thin-set on the cleansurface, to stabilize the surface, andthen apply a suitable membrane towhich the ceramic tile and stone isadhered.

Wood is a questionable substrate fordirect tile attachment, and is absolute-ly unacceptable for exterior areas orany interior wet areas. Wood maycause excessive movement when it

expands from exposure to moisturecompounded by temperature varia-tions, and will warp as it dries, creatingmore detrimental movements. Woodcan be used in dry interior areas wherethe deflection in the floor does notexceed L/360 for ceramic tile or L/720 forstone, but it may potentially limit thechance at a flat surface, let alone a levelor sloping one.

Gypsum wallboard is similar towood in that one cannot use it as asubstrate for tile in exterior applica-tions or wet interior area applicationswithout special precautions. Althoughit is normally not used for floor appli-cations, failures in its wall use canaffect the adjacent flooring. When theinterior of the gypsum wallboard isexposed to moisture, it will deteriorate

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and potentially create a risk of mold.Mold flourishes in wet environ-

ments, and gypsum wallboard is apotential food source. Water-resistantgypsum wallboard (greenboard) andfiber-reinforced gypsum panel backer-board (sometimes used on floors) canbe used as substrates in shower areaswhen installed correctly. Unfortunate-ly, these types of installations are notalways designed or installed correctlyto prevent water intrusion.

Cement backer units are the nextbest alternative to a concrete substrate,as they are not significantly affected bymoisture exposure and provide a goodsurface with which to bond. However,they do not add any significant struc-tural integrity to the installation andcannot compensate for out-of-square

or -plumb wall surfaces, nor floors thatare not level, flat, or sloped (as one canwith a mortar bed installation).

Steel can be a suitable substrate, butspecial precautions must be taken toensure an adequate bond, with the cor-rect adhesive (epoxy adhesive), andthat it will not rust in wet applications.Deflection requirements are the sameas with any other surface to which tilewill be attached, so the steel must beproperly braced.

Is the substrate structurally stable?Deflection in the floor must not

exceed L/360 for ceramic tile or L/720 forstone. Excessive deflection is a bigproblem for installations over woodsub-floors and suspended concreteslabs. Structurally, these substrates

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need to be designed by a qualifiedengineer to ensure compliance withindustry standards for tile.

Is the substrate free of contamination?Contaminated substrates are the

cause of many tile bond failures. Thesurface must be free of dirt, dust, cur-ing compounds, paint, and other typeof coating. The concrete surface mustbe clean, porous, and have a texturedsurface to allow maximum adhesion.

Is the ceramic tile or stone suitablefor the application?

Some types of tile have limitationsrelative to the type of application.Some stones can be adversely affectedby moisture exposure such as mostgreen marbles that can warp during

installation or other stones containingpyrites which may produce rust spots.Some products will wear better thanothers, and may be unsuitable for cer-tain types of applications. For examplethe PEI (Porcelain Enamel Institute)Rating for ceramic tile is the industryrating for the ability of glazed ceramicfloor tile to resist surface abrasion. Forexample class V is the highest ratingqualifying suitability for most com-mercial applications such as malls.The stone industry uses an AbrasionResistance test to qualify suitability.The Marble Institute of America(MIA) states that marble and limestoneshould have an index of at least 12 inheavy traffic areas. Some products donot possess enough slip resistance forwet conditions, while others are too


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textured and cause maintenance issues.Suitability must be qualified withquantitative industry standards.However, installation systems can bedesigned to compensate for someceramic tile or stone weaknesses (i.e.moisture-sensitive stones must beinstalled over a suitable moisture barri-er, and may require installation with awaterless adhesive, such as an epoxy).

Floor preparation for tile involvesunderstanding the characteristics andlimitations of the finished product, aswell as evaluating the substrate andinstallation system to ensure they aresuitable for the intended applicationand use. Any substrate problems thenneed to be corrected with a legitimateremedy meeting industry standards.Industry associations such as Tile

Council of America (TCA) and MIAcan provide information and someguidelines, and the manufacturers ofthe installation systems can providesystem specifications and warranties.Industry consultants can be useful inhelping to assess project needs anddeveloping project specifications.

Liability and risk varies with thequality of the substrate and installationmethod. Here are some of the mostcommon problems leading to tile fail-ures, along with some suggestions foravoiding them:

PROBLEMS AND PREVENTION

MoldThe presence of mold signifies that a

problem exists; specifically, moisture isbeing improperly managed. To thrive,


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mold needs a comfortable temperatureof about 20 C to 30 C (68 F to 86 F)with a relative humidity of greater than60 percent, not to mention a good foodsource. The key to preventing this andother water damaging problems is tofully manage moisture by ensuringproper slope to drains (at both mem-brane level and finished surface), correctdrain assemblies, proper waterproofing,

and sealing of transition areas andmovement joints with quality sealants.The risk is further diminished with theuse of products that do not deteriorateor contribute to the growth of moldwhen exposed to moisture.

CrackingCracks are nature’s way of creating its

own movement joints. As rigid materi-als, concrete, ceramic tile and stone canonly move so much before causingdamage. All surfaces and materialsmove within themselves or as a differ-ential to the material to which they areattached or next to. The movementsmay be caused by deflection, moistureabsorption causing expansion, thermalexpansion or contraction or any com-bination of the above.

The ceramic tile and stone industryhas established limitations and stan-dards for the architect/engineer whendesigning movement joints into all inte-rior and exterior surfaces. In general,TCA method EJ171-03, MovementJoint Design Essentials, suggests havingmovement joints every 7.3 m to 10.9 m(24 ft to 36 ft) for interiors (unless nextto a window or skylight, where it is thentreated as an exterior application), andevery 2.4 m to 3.7 m (8 ft to 12 ft) forexterior floors or walls. Movementjoints are often left out of the detailsbecause designers feel they detract fromthe aesthetics of the installation. Whenplanned during the design of the floor,however, movement joints can easily beincorporated without compromisingthe design. In fact, they frequently canbe used to accentuate key area features.


As an installer you assume liability ifyou don’t install expansions joints.Make sure the architect understands itis their responsibility to specify thedetail and exact locations of expansionjoints on a drawing.

Deflection failuresFloor deflection must not exceed

L/360 for ceramic tile or L/720 for stone.

These measurements must be deter-mined and designed by the projectengineer. Problems are normallycaused by compounding factors. It islikely more than one factor causing afailure. In fact, it is normally the com-bination of several different factors.Thus excessive deflection with lack ofmovement joints increases the risk offailure. It is beyond the installer’sresponsibility to determine deflectionin a floor, but as with expansionsjoints, you assume liability if you don’tmake sure it was engineered to meetindustry standards before you start theinstallation. As stated earlier, it is theresponsibility of the architect to makesure the assembly was properly engi-neered to meet industry standardsprior to beginning the installation.

Bond failureWhen an adhesive (cement based or

otherwise) bonds to the tile or stone butnot the substrate, or vise versa, thensome contamination is likely interfer-ing. Curing compounds used to slowcure the concrete to minimize crackingis ceramic tile and stone’s number oneenemy. These compounds are supposedto dissipate with time, but never soonenough. Then there is dirt, constructiondust, various oversprays, laitance (anaccumulation of fine particles on thesurface of fresh concrete due to anupward movement of water), and othertypes of contamination. Substratesmust be cleaned and/or scarified priorto installation to ensure an adequatebond. There is a very simple qualitativetest (not quantitative) that can be per-


formed on concrete substrates to deter-mine if there may be a potential bond-ing problem (red flag alert). Simplyapply a small amount of water (aboutthe size of a quarter) and watch to seehow readily the concrete absorbs it. If itimmediately absorbs the water, then itis likely contaminate free and onlyneeds to be cleaned. If it immediatelybeads up (like water on a newly waxedcar), there is definitely some sort of acontaminate on the surface and it needsto be removed by scarifying the con-crete. If the concrete doesn’t absorb allof the water within a few minutes theconcrete should be scarified to ensurean adequate bond. Bead blasting is avery effective and popular method ofscarifying floors today.

FlatnessTo ensure ade-

quate drainage, orto compensate foran irregular sur-face, the substratefloor should becovered with a mortar bed to create theprescribed slope, or to level it whennecessary. Whether at a slope or level,the floor needs to be flat for a qualityinstallation. A major problem forinstallers is when architects specify adirect-bond application to the pouredslab to avoid adding a mortar bed tosave money, or when the floor is notdesigned with enough room to accom-modate the mortar bed’s height.

Architects often expect the slab to be


flat enough, or the installer to com-pensate for any irregularities in thefloor during installation. In truth, theslab is often not flat enough withoutspecial preparations and added costs.The substrate ends up having highsand lows, all of which can be adjust-ed... for a price. The highs need grind-ing or bush hammering and the lowsneed filling. Patches and self-leveling

products allow for adjustment, butagain, at a cost not normally providedfor in the specification.

The result of a floor not being flat isthe installation will be more laborintensive and the floor’s irregularitiescan telegraph into the tile or stone(even with conscientious installers).Floors should either be designed withmortar beds, or the specificationsshould allow the installer’s bid price toinclude measures for properly prepar-ing and flattening the floor. Somefloors can be excessively out of leveland not flat, so it is reasonable to limitthe installer’s bid. The specs should callfor no more than an average of 13 mm(0.5 in.) of underlayment. Theinstaller would have to be compensat-ed for anything exceeding this amountwhile trying to achieve 6 mm in 3 m(0.25 in. in 10 ft) American NationalStandards Institute (ANSI), ANSI A-3.1.4.1.1. When the floor is not flat, asan installer, if you don’t provide yourclient with corrective options youassume the responsibility to correct thefloor at your own expense or assumethe liability. Innovative new laser tech-nology is great for the tile contractor toeasily and demonstrably show to theirclient how far a floor is out-of-level orout-of-flat.

MoistureThe most destructive force in the

construction industry is moisture inone form or another. Mold can’t livewithout moisture. Some natural stonesare moisture sensitive and can stain,spall, warp, and show other types of


deterioration from exposure to exces-sive moisture. Efflorescence (a whitishdeposit on surface) is the result of sol-uble salts dissolving and traveling withthe moisture to the surface. A hydro-static condition is when the watersource is higher than the floor surface.This situation is mentioned muchmore often than it actually occurs.The source of moisture is more likely

coming from improper landscapedrain off, from broken pipes, improp-er waterproofing, from high watertables or excessive moisture trapped inor under the slab for one reason oranother. Vapor transmission is whenmoisture travels in the form of a gasfrom a higher concentrated source tothe air at the surface where it diffusesinto the atmosphere. Too much vaportransmission can cause problems, par-ticularly with resilient, laminates,hardwood and carpet floor products.Ceramic tile is much more resistant tomoisture problems, but it does have itslimitations; particularly with the use ofimpervious tile, membranes andgrouts. Where as other floor coveringproducts have standardized the maxi-mum limitation to 3 lbs./1,000 sf/24hrs., as measured by the calcium chlo-ride test (ASTM F-1869), ceramic tileand stone have not set any industrystandards in this area. There is aMaterials & Methods StandardsAssociation (MMSA) committee work-ing on creating ASTM standards formoisture, and there is a Ceramic TileInstitute of America (CTIOA) commit-tee reviewing the use of moisturemeters. Stone is much more sensitiveto moisture and the MIA recommendsthat all on-grade concrete floors have amoisture barrier to minimize potentialproblems. Hydrostatic conditions arenever acceptable.

The question to the installer is howdo you determine if the substrate hastoo much moisture? It is a complexissue and the General Contractor (GC)should be responsible for determining


if the concrete has too much vaportransmission. The GC should hire aqualified testing company to do aCalcium Chloride test to measurevapor transmission, and they should bethe ones to determine if it is suitable.Remember our industry has not setstandards, although some manufactur-ers of tile andinstallation prod-ucts will have anopinion that willlimit their warranty.

For an installer todetermine if thereis a moisture prob-lem or not (so hecan raise a red flag), there are severalmoisture meters on the market that

will measure moisture in the concrete,gypsum or wood substrate. Somemeters use the principle of electricalimpedance measurement to give anaccurate non-destructive moisturereading to a depth of approximately1/2 inch. Others use non-invasive pin-less radio frequency to measure mois-

ture at 3/4 inchdepth. Both typesalso have ahydrometer probemeter where theydrill into the con-crete and measurerelative humidityand temperature

following the relatively new ASTM F-2170-02 method for measuring mois-

TileLetter v March 2004 33

ture. The idea is you can map yourfloors to see a view of relative mois-ture at that time. If you get excessivereadings, then you can have theCalcium Chloride test performed todetermine actual vapor transmissionrates or perform the hydrometer testto measure the moisture within theconcrete over time.

QUALITY ASSURANCE AND CONTROL

The key to a successful installation isto have clear and concise installationspecifications with job-specific qualityassurance and quality sections. First,the right ceramic tile or stone for therespective application must be selectedto ensure suitability. Considerationsmust be made for:

• Resistance: slip, abrasion (wear), andabsorption (stain);

• Freeze-thaw stability for cold cli-mates;

• Durability: compressive strength orspecific gravity and density;

• Maintenance: moisture and chemi-cal sensitivity and surface texture.Next, the best installation system to

be used with the product over a quali-ty substrate must be specified.Waterproof or crack-suppressionmembranes should be included whereneeded for both immediate protectionand long-term insurance. The lowerthe performance of the products andmethods specified, the higher the riskof liability. One should strive toexceed, not just meet, industry stan-


dards by calling out performance spec-ifications. (When one considers imper-fect site conditions and labor, why callout or use reference standards repre-senting the lowest level of acceptableperformance?)

The Construction SpecificationsInstitute’s (CSI’s) MasterFormat™Division 1–General Requirements,Section 01420 calls out QualityAssurance in general terms, as doesSection 01430, which calls out QualityControl guidelines. This should becoordinated with SectionFormat’s™Part 1 – General to qualify the compo-nents of the application from labor toproduct.

This step ensures suitability and setsthe stage for a pre-installation meeting.The meeting is very important, as it pro-vides the opportunity for all work-relat-ed subcontractors to coordinate theirwork and communicate their under-standings and intentions. This meetingshould involve the architect, general

contractor, manufacturer, owner’s repre-sentative and tile contractor.

Part 2 – Products should not onlycall out industry standards, but per-formance qualifications that can bemeasured and substantiated to ensurethe quality of the products and theirfabrication.

The most overlooked part, Part – 3Execution, should specify not onlyinstallation methods in recognizedpublications, including preparatoryactions, post-installation protectionand cleaning, but should provide aQuality Control Plan specifically stat-ing the process, testing, and type andtiming of inspections to be done dur-ing installation to ensure success. Oneshould not leave quality controlaccountability to the installer, as isnormally the case, but rather designatean independent inspector or ownerrepresentative to implement the quali-ty control plan.

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ance of the products and methodsspecified, the higher the risk of liabili-ty. This risk is compounded whenquality assurances and controls are notclearly spelled out in the specifications.Everyone pays when there is a prob-lem, even when it is only with theirloss of time and reputation.

CONCLUSION

Use of ceramic tile and stone hasgrown substantially over the years andthere is no slow down in sight. Weneed the combination of more train-ing and more installers to supply thedemand for qualified installers, whichwill lead to more successful installa-tions and minimize failures. Ceramictile and stone failures hurt all of us inour industry; not only due to exces-sive cost for repairs or replacements,but it tarnishes our industry’s imagein the eyes of potential buyers. Theend user seeks out our products notonly because they provide a verypleasing and prestigious look withmany design options, but because ourindustry provides an enduring surfacethat can last the life of a buildingwhen installed correctly. That is whatthe customer wants, that is what theypay for, and that is what they shouldget. Quality specifications and propersubstrate preparations are key to last-ing installations, but both the archi-tect and the installer have to be taughtto understand the extent of thisprocess. We as an industry need toinvest in our employees and ourfuture by providing continuous train-ing to our labor force.

AUTHOR

Ceramic Tile Consultant, DonatoPompo CTC CSI CDT MBA is thefounder of Ceramic Tile and StoneConsultants (CTaSC). Donato has over25 years experience in the ceramic tileand stone industry from installation todistribution, to manufacturing of instal-lation products. CTaSC provides servicesin Job Problem Investigations, QualityControl Services for products and instal-lation methods to include writing archi-tectural specifications, Training Pro-grams to include on-site training, andonline courses from his new University ofCeramic Tile and Stone (UofCTS) cam-pus, Market Research and OutsourcingServices and Business Planning services.You can reach Donato by visiting his website at www.CTaSC.com, or e-mail [email protected], or by calling619-669-2967.

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material allowing for the application of the tile? - … · proper slope to drains ... as rigid...

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