ACT Large Format Tile & Substrate Preparation

Under current ANSI and TCNA Handbook definitions, a tile is classified as 'large format tile' (LFT) when it has at least one edge of what minimum length?

• A8 inches
• B12 inches
• C15 inches
• D24 inches

Which ANSI installation standard specifically addresses the installation of large-and-heavy tile (LFT)?

• AANSI A108.5
• BANSI A108.10
• CANSI A108.19
• DANSI A136.1

For a tile with any edge 15 inches or longer, what is the maximum allowable substrate variation from the required plane over a 10-foot span?

• A1/16 inch
• B1/8 inch
• C1/4 inch
• D3/8 inch

For tile installations where every edge of the tile is less than 15 inches, what substrate flatness tolerance applies?

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

For LFT substrates, the standard also restricts deviation in a shorter span. Within 24 inches the substrate cannot be more than how much out of plane?

• A1/64 inch
• B1/32 inch
• C1/16 inch
• D1/8 inch

Which ANSI mortar standard identifies a 'large-and-heavy-tile' (LHT/LFT) mortar with non-sag and extended open-time characteristics?

• AANSI A118.1
• BANSI A118.4
• CANSI A118.4T
• DANSI A136.1

In a dry interior residential installation, what is the minimum mortar contact area required on the back of LFT?

• A50%
• B65%
• C80%
• D95%

In wet areas (shower walls, pools) and all exterior installations, what minimum mortar coverage applies under LFT?

• A75%
• B80%
• C90%
• D95%

What technique is normally required on the back of LFT to consistently achieve 95%/80% mortar coverage?

• ASpot-bonding the four corners
• BBack-buttering (flat back-trowel)
• CAdhesive-only setting
• DSetting tile face-down in mortar

Under TCNA EJ171, what is the maximum spacing of intermediate movement joints in an interior tile assembly with normal temperature and moisture exposure?

• A8 to 12 feet
• B20 to 25 feet
• C30 to 40 feet
• DNot required for interior work

Under TCNA EJ171, what is the required spacing for intermediate movement joints in an exterior tile installation?

• A4 to 6 feet
• B8 to 12 feet
• C20 to 25 feet
• DNo fixed spacing

Per ANSI A108.02, for grout joints from 1/16" to less than 1/4" wide on a floor, the allowable lippage between adjacent tiles is:

• A1/64" plus inherent warpage
• B1/32" plus inherent warpage
• C1/16" plus inherent warpage
• D1/8" plus inherent warpage

For grout joints 1/4 inch or wider on a floor, ANSI A108.02 allows what lippage between adjacent tiles?

• A1/32" plus inherent warpage
• B1/16" plus inherent warpage
• C1/8" plus inherent warpage
• D3/16" plus inherent warpage

When laying out an LFT installation, the TCNA Handbook recommends that cut tiles at the perimeter not be less than what fraction of a full tile?

• A1/8 of a tile
• B1/6 of a tile
• C1/3 of a tile
• D1/2 of a tile

Which of the following is the BEST method to assess and correct out-of-plane substrate before installing LFT?

• ASkim coat with a non-modified thinset and tile immediately
• BApply a self-leveling underlayment (SLU) or patching mortar to bring the substrate within…
• CBuild out low spots with extra mortar at install time
• DIgnore deviations and rely on leveling clips

Which orientation of trowel ridges and tile placement gives the BEST chance of collapsing ridges into a continuous bed under LFT?

• ARandom trowel direction and random tile rotation
• BTrowel ridges in one direction and slide the tile perpendicular to the ridges
• CUse a swirl trowel pattern and press straight down
• DSpread mortar with the flat side of the trowel only

Which tool is used to seat LFT into the mortar bed without point-loading the tile and to even out surface variations?

• ABeat block (rubber-faced block) with a mallet
• BTrowel handle
• CPower drill
• DSnap cutter

Which scenario REQUIRES a movement joint at the perimeter of a tile installation per TCNA EJ171?

• AOnly where the tile meets carpet
• BWherever tilework abuts restraining surfaces such as walls, columns, curbs, pipes, or dis…
• COnly at exterior walls
• DOnly when the tile is over 24 inches

Per EJ171, the minimum width of a movement joint is:

• A1/32 inch
• B1/16 inch
• C1/8 inch
• D1/4 inch

Which ASTM standard is referenced by EJ171 for elastomeric joint sealants used in tile movement joints?

• AASTM C920
• BASTM C150
• CASTM E96
• DASTM C627

For a 24" x 48" porcelain tile installed on a residential interior floor, which combination correctly states the substrate flatness, mortar standard, and coverage required?

• A1/4" in 10', A118.4, 80% dry interior
• B1/8" in 10', A118.4T, 80% dry interior
• C1/8" in 10', A118.4T, 95% dry interior
• D1/4" in 10', A118.1, 65% dry interior

Which statement BEST describes the difference between 'flatness' and 'levelness' on an LFT substrate?

• AThey are identical terms
• BFlatness measures local deviation from a true plane; levelness measures deviation from ho…
• CFlatness is for walls and levelness is for floors
• DLevelness is more important than flatness for LFT

Which mortar property is MOST important for LFT installed on a wall?

• AHigh shrinkage
• BNon-sag formulation (A118.4T)
• CFast initial set under 10 minutes
• DHigh cement content with no polymer

Which inspection technique is used in the field to verify mortar coverage after installation?

• ATap-sounding only
• BRemoving at least three tiles or tile assemblies and visually inspecting back-of-tile con…
• CCounting trowel ridges before tile is set
• DMeasuring grout joint width

Which of the following is a LEGITIMATE use of leveling clip systems on LFT?

• ATo compensate for a substrate that exceeds 1/8" in 10'
• BTo eliminate the need for back-buttering
• CTo temporarily align adjacent tile edges during cure and reduce lippage on a properly pre…
• DTo replace movement joints

Which LFT-related update has appeared in recent editions of the TCNA Handbook?

• AReducing the LFT threshold to 8 inches
• BAdding methods and details for gauged porcelain tile and tile panels/slabs
• CEliminating the 80% coverage rule
• DRemoving EJ171

What is the MOST common cause of LFT failure tracked back to substrate preparation?

• ASubstrate exceeding the 1/8"-in-10' flatness tolerance, producing voids and lippage
• BUse of a leveling clip system
• CUse of A118.4T mortar
• DPerimeter movement joints

Which of these BEST describes a polymer-modified thinset mortar?

• AThinset with a portland-only binder and no polymer
• BThinset containing a redispersible polymer that improves bond strength, flexibility, and…
• CA pure latex compound with no portland cement
• DA grout product, not a setting mortar

Which statement about installing modified vs unmodified thinset over uncoupling membranes is MOST accurate?

• AAlways use modified thinset; the membrane manufacturer is irrelevant
• BFollow the membrane manufacturer's instructions — many uncoupling membranes specifically…
• CModified thinset cures faster in any configuration
• DUnmodified thinset is never appropriate for LFT

Which TCNA Handbook method number references thin-bed installation over an uncoupling membrane?

• AF125
• BB411
• CRH230
• DF141

Which subfloor deflection criterion applies to a wood-frame floor that will receive ceramic tile?

• AL/240
• BL/360 for ceramic, L/720 for natural stone
• CL/480 minimum for all tile
• DL/120

On a wood-frame subfloor, which substrate condition is MOST likely to disqualify an LFT installation regardless of mortar selection?

• ASubstrate is dry
• BSubstrate exceeds 1/8" in 10' or 1/16" in 24", or deflection exceeds L/360
• CSubstrate has been swept clean
• DSubstrate has been primed

Which trowel notch profile is MOST commonly recommended for LFT bonding work?

• A1/8" V-notch
• B1/4" square-notch
• C1/2" x 1/2" or larger U/square-notch (and back-butter)
• DNo notch — flat trowel only

After spreading mortar with a notched trowel, you set an LFT, slide it perpendicular to the ridges, and tap with a beat block. Why?

• ATo make the trowel ridges visible after install
• BTo collapse the ridges into a continuous bed, eliminate air, and achieve 95%/80% coverage
• CTo accelerate cure
• DTo increase lippage so grout looks even

When an LFT job is laid out, which is the BEST first step before placing any tile?

• ASpread mortar across the entire area
• BSnap a dry layout, plan cut sizes, and align control/movement joints with substrate joints
• CBegin in a corner with the smallest cut
• DSet tile at the doorway first

In an LFT installation, expansion joints in the substrate must:

• ABe tiled directly over with no special detail
• BBe honored — the tile movement joint must align with the substrate joint
• CBe filled with mortar only
• DBe ignored if the tile is large

Which is NOT typically appropriate for filling an EJ171 movement joint?

• ASingle-component ASTM C920 polyurethane sealant
• B100% silicone (ASTM C920) sealant
• CCementitious grout
• DMulti-component urethane sealant (ASTM C920)

Which describes the LFT lippage standard verification process per ANSI A108.02?

• ALippage is measured from a 10-foot straightedge
• BLippage is measured between adjacent tiles at their grout joint and compared to the allow…
• CLippage is measured only after grout has cured
• DLippage is measured only at the perimeter

What is 'inherent warpage' in the LFT lippage context?

• AA defect introduced by the installer
• BThe natural curvature of the tile from manufacture, which is added to the lippage allowan…
• CA grout color difference
• DA substrate movement value

Self-leveling underlayments (SLUs) are commonly used in LFT prep. What property is MOST important?

• AColor match to the grout
• BCalibrated flow to meet 1/8"-in-10' flatness when poured and a published compressive stre…
• CSlow set so the floor can be re-pumped after 24 hours
• DBond to non-primed substrates

Which mortar is BEST suited for setting LFT on a fully cured concrete substrate that is acceptably flat?

• AA dry-set mortar meeting ANSI A118.1 only
• BAn ANSI A118.4T large-and-heavy-tile mortar
• CA 100% silicone adhesive
• DA type-S masonry mortar

During LFT installation, ambient and substrate temperature should generally stay within what range during installation and initial cure?

• A20°F to 40°F
• B50°F to 95°F (typical manufacturer range)
• C100°F to 130°F
• DNo temperature range matters

What is 'open time' for a thinset mortar?

• AThe interval after mixing during which trowel ridges remain pliable enough to bond
• BThe time before mixing
• CThe cure time before grouting
• DThe shelf life of the bag

How can an installer verify that open time has not been exceeded on a fresh trowel ridge?

• ATouch the ridge — if mortar transfers wet to the fingertip, open time is acceptable
• BWait 30 minutes after troweling
• CApply more water to the surface
• DCover the ridges with plastic

For LFT, the BEST way to spread mortar when working with a partner is:

• AOne installer troweling all the mortar in advance for the entire room
• BTrowel only as much mortar as can be tiled within the mortar's open time, in straight rid…
• CTrowel mortar onto the back of the tile only
• DTrowel the mortar in random circles

Which of the following is NOT an acceptable way to handle a substrate that is out of LFT flatness tolerance?

• AInstall a self-leveling underlayment
• BPatch low areas with a manufacturer-approved patching mortar and re-check
• CBuild up low spots with extra thinset at installation
• DGrind down high points

On the wall, an LFT installation requires:

• ANo bond verification — wall installs do not require coverage checks
• B95% mortar contact with full edge and corner support
• CSpot bonding at the four corners only
• DAdhesive only at the top edge