Nevada C-20 Tiling Contractor Examination

Under NAC 624.370, what work does a Nevada C-20 tiling license authorize?

• AInstallation of ceramic, encaustic, vitreous, and similar tile by suction and adhesives,…
• BStructural masonry walls of hollow clay tile
• CFinish carpentry and hardwood flooring
• DPlumbing of shower valves and drain lines

Which ANSI specification covers general requirements for structures, substrates, and preparation before ceramic tile is installed?

• AANSI A118.1
• BANSI A108.01
• CANSI A136.1
• DANSI A108.10

A concrete slab still has a film of curing compound. What does ANSI A108.01 require before bonded thin-set tile?

• ALeave the film to keep the slab from drying under the mortar
• BPrime the film with PVA drywall primer and set tile the same day
• CRemove the curing compound so the surface is clean and free of bond-breaking coatings
• DCover the film with unsanded grout and then thin-set

Why is paper-faced gypsum board the wrong backing for a tiled tub surround?

• APaper-faced gypsum is too hard for thin-set to bond
• BPaper-faced gypsum is waterproof, so a membrane cannot stick
• CANSI A136.1 requires paper-faced gypsum behind every wet wall
• DPaper-faced gypsum deteriorates when it stays wet and is not an accepted wet-area tile ba…

A cementitious backer unit is installed on a shower wall. Why is a waterproof membrane still required by typical TCNA wet-area methods?

• ACBU panels are water-resistant tile backings, not waterproof barriers
• BCBU panels are already waterproof, so a membrane is only decorative
• CANSI A118.9 classifies CBU as an A118.10 membrane
• DMembranes are required only on dry closet walls

What minimum slope do TCNA wet-area methods and plumbing practice require for a tiled shower floor toward the drain?

• A1/16 inch per foot
• B1/4 inch per foot
• C1 inch per foot
• DNo slope if a waterproof membrane is used

Besides curing compound, which contaminants must ANSI A108.01 surfaces be free of before bonded tile?

• ADust, oil, grease, paint, and wax
• BOnly standing water; oil films may remain
• COnly laitance; paint is an approved bonding primer
• DNothing — thin-set bonds through any film

Why is moisture-resistant paper-faced gypsum (green board) still rejected as the sole backing in a tiled shower?

• AGreen board is rated as an A118.10 waterproof membrane
• BGreen board is harder than CBU and cracks every tile
• CThe paper face and gypsum core still deteriorate under prolonged wet-area moisture
• DANSI A108.11 requires green board in every shower

Unless the mortar manufacturer states a shorter wait, how long is a new concrete slab commonly allowed to cure before bonded ceramic tile?

• A4 hours
• B28 days
• CThe same day the slab is finished
• DOne year in every case

What is laitance on a concrete slab, and why must it be removed before bonded tile?

• AA beneficial hard skin that waterproofs the slab
• BA factory-applied A118.10 waterproof membrane
• CThe reinforcing wire used in an unbonded mortar bed
• DA weak surface layer of cement paste and fines that will fail in shear under the bond coat

For ceramic tile with all edges shorter than 15 inches, what is the commonly cited ANSI A108.02 maximum substrate variation from the required plane on a 10-foot straightedge?

• A1/2 inch in 10 feet
• B1/8 inch in 10 feet and 1/16 inch in 2 feet
• C1/4 inch in 10 feet
• D3/4 inch in 10 feet

An 18-by-18-inch porcelain floor is specified. What substrate flatness does ANSI A108.02 require for tile with at least one edge 15 inches or longer?

• ANo more than 1/4 inch in 10 feet, with no short-span limit
• BNo more than 3/8 inch in 10 feet if a medium-bed mortar is used
• CNo more than 1/2 inch in 10 feet if the tile is rectified
• DNo more than 1/8 inch in 10 feet and no more than 1/16 inch in 2 feet, measured from the…

What traditional live-load deflection limit does the TCNA Handbook use for framed floors that will receive ceramic or porcelain tile?

• AL/120
• BL/360
• CL/180
• DL/960

A wood-framed floor will receive 12-by-12-inch marble. Which deflection criterion is the stricter industry requirement commonly applied to natural stone?

• AL/360
• BL/240
• CL/720
• DNo limit if a crack-isolation membrane is used

Which pair correctly matches the cementitious backer unit material specification with the interior CBU installation specification?

• AANSI A118.1 for the board; ANSI A108.5 for installation
• BANSI A118.10 for the board; ANSI A108.13 for installation
• CANSI A118.9 for the board; ANSI A108.11 for installation
• DANSI A136.1 for the board; ANSI A108.4 for installation

Which ANSI material specification covers load-bearing, bonded waterproof membranes used under thin-set ceramic tile and dimension stone?

• AANSI A118.10
• BANSI A118.1
• CANSI A118.6
• DANSI A136.1

Which ANSI material specification covers crack-isolation membranes for thin-set ceramic tile and dimension stone?

• AANSI A118.3
• BANSI A118.7
• CANSI A118.9
• DANSI A118.12

What is the purpose of a cleavage membrane under an unbonded floor mortar bed?

• ATo replace movement joints in the tile
• BTo serve as the finish wearing surface
• CTo separate the mortar bed from the substrate so the tile assembly can move independently…
• DTo bond the reinforcing wire to the concrete

In a typical unbonded (floating) mortar-bed floor method, what is the usual minimum thickness of the reinforced mortar bed?

• A1-1/4 inches, to cover the reinforcing wire over a cleavage membrane
• B1/4 inch, the same as a thin-set bond coat
• C3/8 inch if latex is added to the mud
• D3 inches, to replace the concrete slab

Compared with an unbonded mortar bed, why can a bonded mortar bed be thinner?

• AIt uses organic adhesive instead of portland cement
• BIt is always installed over a cleavage membrane
• CIt is bonded to the slab and does not have to bury reinforcing wire, so a 3/4-inch minimu…
• DIt never requires a clean, sound concrete surface

Under TCNA EJ171, where must movement joints be provided in interior tilework in addition to any field joints?

• AOnly at the exact center of every room
• BWhere tile abuts restraining surfaces such as perimeter walls, columns, curbs, pipes, and…
• COnly under carpet transitions, never at walls
• DNever at perimeters if cement grout is used

A slab will receive bonded thin-set tile. How should moisture vapor emission or in-slab relative humidity be handled?

• AIgnore moisture; portland-cement mortar is unaffected
• BSeal the slab with household floor wax
• CTest by the specified method and compare the result to the mortar and membrane manufactur…
• DWet the slab until it is saturated, then set tile immediately

Why is particleboard rejected as a setting surface for ceramic tile?

• AIt is too expensive compared with plywood
• BIt swells, weakens, and delaminates with moisture and does not provide a stable tile subs…
• CANSI A108.01 lists particleboard as the preferred wet-area backing
• DThin-set bonds to particleboard better than to exterior-glue plywood

For a wood-framed residential floor that will receive ceramic tile, what substrate approach do TCNA methods and Builder's Guide to Floors expect?

• AA single layer of 1/4-inch lauan over 24-inch joists
• BParticleboard underlayment glued with carpenter's glue
• CA stiff, dry wood system — typically two layers of exterior-glue plywood or plywood plus…
• DOSB finish flooring with no second layer and no deflection check

For exterior tilework, what field-joint spacing range does TCNA EJ171 give as a guideline?

• A25 to 40 feet in each direction
• B50 feet in each direction if modified mortar is used
• C8 to 12 feet in each direction, closer if the temperature range is severe
• DNo field joints outdoors because the tile can expand freely

How does TCNA EJ171 change interior field-joint spacing when the tile will see moisture or direct sunlight?

• AJoints may be omitted because heat and moisture soften cement grout
• BJoints are spaced farther apart than in a dry interior room
• COnly grout color needs to change; spacing stays at 40 feet
• DJoints are placed more frequently; the EJ171 guideline is 8 to 12 feet in each direction

A framed floor spans 15 feet between supports. If the ceramic-tile live-load deflection limit is L/360, what is the maximum allowed deflection?

• A0.25 inch
• B0.50 inch
• C1.00 inch
• D1.50 inches

A shower floor is 6 feet from the curb to a center drain. At the required 1/4 inch per foot slope, how much lower must the drain be than the high point at the curb?

• A1/4 inch
• B3/4 inch
• C1-1/2 inches
• D6 inches

When installing interior CBU under ANSI A108.11, which combination is the accepted practice?

• ASet floor panels in a thin-set bond coat, fasten with corrosion-resistant CBU fasteners,…
• BButt sheets tight, fasten with drywall nails, and tape with paper drywall tape and joint…
• CGlue CBU with construction adhesive only and skip fasteners
• DHang CBU like drywall with no mortar under floor panels and no joint treatment

A slab has a 1/4-inch-wide, out-of-plane faulted crack. A crack-isolation membrane is proposed so tile can be bonded across it. What is the correct response?

• AA118.12 membranes typically address limited in-plane cracks; a faulted or wide crack need…
• BAny crack can be ignored if the membrane is A118.12
• CFill the fault with unsanded grout and set tile the same day
• DA crack-isolation membrane also replaces EJ171 joints at the walls

Which ANSI installation specification covers setting ceramic tile with dry-set, modified dry-set, EGP, or improved modified dry-set cement mortar?

• AANSI A108.10
• BANSI A108.5
• CANSI A108.01
• DANSI A136.1

What does ANSI A118.1 specify?

• AOrganic adhesives for ceramic tile
• BStandard cement grouts
• CDry-set portland cement mortar (unmodified thin-set)
• DLoad-bearing waterproof membranes

What does ANSI A118.4 specify?

• AModified dry-set cement mortar (polymer-modified thin-set)
• BUnmodified dry-set mortar only
• CChemical-resistant furan grout
• DCementitious backer units

What does ANSI A136.1 specify?

• AImproved modified dry-set mortar
• BOrganic adhesives (mastics) for ceramic tile
• CCrack-isolation membranes
• DHigh-performance cement grouts

ANSI A108.5 requires what minimum mortar contact coverage for interior dry ceramic-tile installations?

• A50 percent
• B80 percent
• C95 percent
• D25 percent if each corner has a dab of mortar

What minimum mortar coverage is required for ceramic tile in wet or exterior installations?

• A80 percent, the same as a dry interior closet
• B60 percent if a waterproof membrane is used
• C95 percent contact, with ridges collapsed so water and voids are not trapped under the ti…
• DNo minimum, because grout will fill the voids later

When 95 percent coverage is specified, what additional step does ANSI A108.5 recognize?

• AAdd extra mixing water so the mortar self-levels
• BButter only the four corners and the center
• CSkip troweling the substrate and butter only the tile face
• DBack-butter each tile with bond coat, or select a notch size that will produce the requir…

After the bond coat is keyed in with the flat side of the trowel, what is the next A108.5 step?

• AComb additional mortar with the notched side, then embed the tile
• BSprinkle dry portland cement over the slab and set tile in the dust
• CSpot five dabs of mortar and press the tile onto them
• DPour grout first so it can act as the setting bed

A setter finds a 3/8-inch depression in a 10-foot run on a slab that will receive thin-set floor tile. What is the correct preparation?

• AFill the low area by stacking extra thin-set under those tiles
• BIgnore the depression if the tile is large enough to bridge it
• CCorrect the plane with a suitable portland-cement patch, self-leveling underlayment, or m…
• DCover the depression with unsanded grout and then thin-set

Why is organic adhesive (mastic) the wrong setting material for a shower receptor floor?

• AOrganic adhesives are interior mastics and are not specified for submerged or constantly…
• BOrganic adhesives are the only products that meet A118.10
• COrganic adhesives are freeze-thaw paving mortars
• DANSI A108.5 requires mastic on every wet floor

Why does Setting Tile (Byrne) and standard stone practice call for white thin-set under light or translucent marble?

• AWhite mortar is the only product that meets A118.1
• BGray mortar cannot bond to stone
• CWhite mortar eliminates movement joints in marble floors
• DGray mortar can shadow or stain through light stone; white mortar keeps the color true

How should dry-set or modified thin-set be mixed?

• ATo a soup that pours like grout, using extra water for workability
• BBy the manufacturer's water ratio to a lump-free, trowelable consistency that holds a not…
• CWith no water; spread the powder dry and mist it after the tile is set
• DWith gypsum plaster added to speed the set

After the initial mix, what is slaking of thin-set mortar?

• ALetting the mortar stand a few minutes, then remixing without adding water so the polymer…
• BAdding a second measure of water to thin the batch
• CDumping the batch if it sits more than 30 seconds
• DHeating the mortar above 140°F to speed set

A combed mortar bed has skinned over and is no longer sticky. What should the setter do before placing more tile?

• ASet the tile anyway; skinning improves bond
• BMist the skin with water and continue
• CRemove the dried mortar and replace it with fresh mortar, or recomb only if the mortar is…
• DCover the skin with grout and beat the tile in

At about what angle is a notched trowel commonly held when combing thin-set ridges?

• A0 degrees, dragged flat so no ridges form
• B45 degrees, so the notches leave uniform ridges
• C90 degrees, chopped vertically into the slab
• D180 degrees, with the handle pointing at the floor

What does ANSI A118.15 specify compared with A118.4?

• AA weaker, economy dry-set with no polymer
• BOrganic mastic for dry walls only
• CImproved modified dry-set cement mortar that uses the same tests as A118.4 but with stric…
• DA grout specification, not a mortar

Which ANSI specification covers chemical-resistant, water-cleanable tile-setting and grouting epoxy?

• AANSI A118.1
• BANSI A118.3
• CANSI A118.6
• DANSI A136.1