I85PREP
⌘ K
ACT Large Format Tile study materials
ACT Large Format Tile study resources

ACT Large Format Tile practice questions

One question at a time. Build your ACT Large Format Tile understanding.

First 50 of 200 questions. Each one lists the choices, the correct answer, and an explanation. The checker at the top of this page saves progress in this browser when it is available.

Continue in the practice tool above to load more questions, 50 at a time.

Question 1Substrate Preparation and Evaluation

What is the primary purpose of evaluating a substrate before installing large format tile?

  1. To determine the tile layout pattern
  2. To confirm the substrate can support the tile and bond properly Correct answer.
  3. To decide which grout color will look best
  4. To estimate the number of tiles needed for the room

Explanation

Substrate evaluation verifies that the surface is sound, flat, clean, and compatible with the adhesive system so the tile can be supported and bonded durably. Layout, grout color, and quantity estimates are separate planning steps.

Question 2Substrate Preparation and Evaluation

Which condition most commonly causes bond failure of large format tile over a concrete slab?

  1. The presence of control joints in the slab
  2. Use of a latex-portland cement mortar
  3. Contamination such as curing compounds, sealers, or dust on the surface Correct answer.
  4. A slight color variation in the concrete

Explanation

Curing compounds, sealers, oils, and dust act as bond breakers between the mortar and the slab. These contaminants must be removed before installation. Color variation and control joints are normal slab features.

Question 3Substrate Preparation and Evaluation

A substrate must be flat enough to prevent lippage with large format tile. Which standard tool is used to check flatness over a large area?

  1. A chalk line
  2. A torpedo level
  3. A straightedge of specified length Correct answer.
  4. A framing square

Explanation

Flatness is checked with a straightedge of the length specified by the applicable standard, and the gap beneath it is measured. Short tools like torpedo levels or squares cannot reveal long-wave deviations.

Question 4Substrate Preparation and Evaluation

Why must deflection be evaluated before installing large format tile over a wood-framed floor?

  1. Excessive deflection can crack tile and break the bond Correct answer.
  2. Deflection changes the cure time of the mortar
  3. Deflection affects the color of the tile
  4. Deflection determines the grout joint width

Explanation

Floors that flex beyond the allowable limit for the tile assembly can crack tile and debond it. The framing must meet a specified deflection criterion before tile is installed.

Question 5Substrate Preparation and Evaluation

What is the purpose of a moisture test on a concrete slab before tile installation?

  1. To verify the slab's reinforcement spacing
  2. To measure the slab's compressive strength
  3. To check the slab's surface profile
  4. To confirm the slab's moisture emission is within the flooring system's limit Correct answer.

Explanation

Moisture testing quantifies vapor emission or relative humidity so the adhesive and tile assembly are not installed over a slab that exceeds their tolerance. Excessive moisture can cause debonding and efflorescence.

Question 6Substrate Preparation and Evaluation

Which substrate is generally unsuitable for direct bonding of large format tile without an intervening membrane or underlayment?

  1. Clean, cured concrete slab
  2. Exterior-grade plywood installed to standard Correct answer.
  3. Cement backer board
  4. Cured portland cement mortar bed

Explanation

Wood-based substrates expand and contract with moisture and are dimensionally unstable for direct tile bonding, so they require a suitable underlayment or membrane. Cementitious substrates are commonly acceptable when properly prepared.

Question 7Substrate Preparation and Evaluation

What does surface profile refer to in substrate preparation?

  1. The slope of the floor toward a drain
  2. The roughness or texture of the substrate surface Correct answer.
  3. The width of the grout joints
  4. The thickness of the tile

Explanation

Surface profile describes the microscopic texture that affects mechanical keying of the mortar. It is distinct from slope, which is a drainage consideration.

Question 8Substrate Preparation and Evaluation

Which practice best prepares a dusty concrete slab for large format tile?

  1. Applying a sealer to lock down the dust
  2. Applying mortar directly over the dust
  3. Wetting the dust into the surface
  4. Vacuuming and scrubbing to remove loose material Correct answer.

Explanation

Dust and loose material must be physically removed so the mortar contacts sound substrate. Sealing over dust or troweling mortar onto it creates a bond-breaking layer.

Question 9Substrate Preparation and Evaluation

A tile installer is evaluating a concrete slab for large format tile. The slab has a high spot that creates lippage at a joint. What is the most appropriate corrective action?

  1. Increase the mortar thickness under the tile at the low side
  2. Build up the surrounding area with thinset during installation
  3. Install the tile with wider grout joints
  4. Grind down the high spot to bring the surface within tolerance Correct answer.

Explanation

High spots must be reduced by grinding so the substrate meets flatness tolerance. Attempting to compensate with mortar thickness during installation is unreliable and can cause lippage or hollow spots.

Question 10Substrate Preparation and Evaluation

When checking flatness of a substrate for large format tile, a 10-foot straightedge reveals a 3/8 inch gap in the middle of the span. What does this indicate?

  1. The substrate is within tolerance for large format tile
  2. The gap is acceptable if mortar is applied thicker
  3. The substrate exceeds allowable flatness tolerance and needs correction Correct answer.
  4. The straightedge is defective

Explanation

Large format tile requires a tighter flatness tolerance than smaller tile, and a 3/8 inch deviation over 10 feet typically exceeds that limit. The substrate must be flattened before installation.

Question 11Substrate Preparation and Evaluation

What is the recommended method for addressing a crack in a concrete slab before installing large format tile?

  1. Honor the crack with a joint or use an appropriate crack isolation membrane Correct answer.
  2. Paint over the crack with a bonding agent
  3. Fill the crack and install tile directly over it
  4. Ignore the crack if it is narrow

Explanation

Cracks in concrete can transfer movement to the tile, so they must be isolated with a membrane or honored with a joint. Simply filling or painting over a crack does not accommodate movement.

Question 12Substrate Preparation and Evaluation

A wood subfloor is being evaluated for large format tile. Which factor is most critical to verify in addition to deflection?

  1. The number of nails used
  2. The subfloor's paint color
  3. The subfloor's thickness and joist spacing Correct answer.
  4. The subfloor's age

Explanation

Subfloor thickness and joist spacing determine deflection and load capacity for the tile assembly. These structural details must meet the requirements for the tile and underlayment system.

Question 13Substrate Preparation and Evaluation

Which test method is commonly used to measure moisture vapor emission from a concrete slab?

  1. Pull-off adhesion test
  2. Compaction test
  3. Calcium chloride test Correct answer.
  4. Slump test

Explanation

The calcium chloride test measures moisture vapor emission rate from a concrete slab. Slump and compaction tests evaluate concrete placement, and pull-off tests measure adhesion strength.

Question 14Substrate Preparation and Evaluation

When evaluating a gypsum-based substrate for large format tile, what is the primary concern?

  1. Its fastener pattern
  2. Its sensitivity to moisture and need for a suitable sealer or membrane Correct answer.
  3. Its thermal conductivity
  4. Its color uniformity

Explanation

Gypsum substrates are moisture-sensitive and generally require sealing or a membrane before tile installation. Moisture can degrade the gypsum and affect adhesion.

Question 15Substrate Preparation and Evaluation

What does a hollow sound when tapping a cured mortar bed indicate during substrate evaluation?

  1. The mortar bed is fully bonded
  2. There may be a debonded or hollow area that needs repair Correct answer.
  3. The mortar bed is too wet
  4. The tile size is too large

Explanation

A hollow sound suggests the mortar bed has separated from the substrate or contains voids. These areas can lead to failure under load and should be repaired before tiling.

Question 16Substrate Preparation and Evaluation

Which condition on a substrate would most likely require priming before applying a self-leveling underlayment?

  1. A porous or dusty surface that absorbs moisture quickly Correct answer.
  2. A surface with a slight slope
  3. A surface with a painted stripe
  4. A clean, sound, dry concrete surface

Explanation

Porous or dusty surfaces can absorb water from the underlayment too quickly, causing poor flow and bonding, so a primer is used. Clean sound concrete may not require priming depending on the product.

Question 17Substrate Preparation and Evaluation

What is the purpose of a slip sheet or cleavage membrane in substrate preparation?

  1. To bond the tile more strongly to the substrate
  2. To increase the substrate's compressive strength
  3. To reduce the tile's weight
  4. To isolate the tile assembly from movement in the substrate Correct answer.

Explanation

A cleavage membrane isolates the tile from substrate movement, preventing cracks from reflecting into the tile. It does not increase bond strength or structural capacity.

Question 18Substrate Preparation and Evaluation

A concrete slab has a curing compound applied. What must be done before installing tile?

  1. Remove the curing compound by mechanical means Correct answer.
  2. Wet the slab thoroughly
  3. Apply a primer over the compound
  4. Install tile directly over the compound

Explanation

Curing compounds form a film that prevents the mortar from bonding, so they must be removed mechanically. Priming over a curing compound does not restore bond.

Question 19Substrate Preparation and Evaluation

Which substrate condition is most likely to cause efflorescence in a tile installation?

  1. Excessive moisture migrating through the substrate Correct answer.
  2. A properly installed vapor barrier
  3. A dry, sealed concrete slab
  4. A clean cement backer board

Explanation

Efflorescence occurs when moisture carries soluble salts to the surface and evaporates. Controlling moisture migration through the substrate reduces the risk.

Question 20Substrate Preparation and Evaluation

An installer is evaluating a substrate for large format tile and finds the surface is sound but has a 1/8 inch deviation over 10 feet. What is the most appropriate conclusion?

  1. The substrate is likely within flatness tolerance and may proceed Correct answer.
  2. The substrate must be demolished and replaced
  3. The deviation requires a full self-leveling pour
  4. The deviation will not affect large format tile

Explanation

A 1/8 inch deviation over 10 feet is generally within the tighter flatness tolerance required for large format tile. Small deviations within tolerance do not require demolition or full leveling.

Question 21Substrate Preparation and Evaluation

Why is a moisture barrier important under a tile assembly over a slab-on-grade?

  1. It eliminates the need for a mortar bed
  2. It reduces moisture vapor transmission into the tile assembly Correct answer.
  3. It improves the tile's color consistency
  4. It increases the slab's compressive strength

Explanation

A moisture barrier limits vapor transmission from the ground through the slab, protecting the adhesive and tile from moisture-related failure. It does not change structural strength or tile color.

Question 22Substrate Preparation and Evaluation

A substrate has a bond-breaking contaminant that cannot be fully removed. What is the most appropriate course of action?

  1. Increase the grout joint width
  2. Use a bonding primer over the contaminant
  3. Remove and replace the contaminated substrate or use an isolation system Correct answer.
  4. Install tile with a thicker mortar layer

Explanation

If a contaminant cannot be removed, the contaminated layer must be replaced or isolated so the mortar bonds to a sound surface. Thicker mortar or wider joints do not solve a bond-breaking condition.

Question 23Substrate Preparation and Evaluation

Which statement best describes the relationship between substrate flatness and lippage in large format tile?

  1. Greater substrate flatness deviation increases the risk of lippage Correct answer.
  2. Lippage only occurs with small tile
  3. Lippage is unrelated to substrate flatness
  4. Lippage is caused solely by grout color

Explanation

Large format tile is less able to conform to substrate deviations, so greater flatness deviation increases the likelihood of lippage at tile edges. Flatter substrates reduce lippage risk.

Question 24Substrate Preparation and Evaluation

During substrate evaluation, a floor is found to have a deflection that exceeds the allowable limit for the tile assembly. What is the most appropriate action?

  1. Proceed with installation using a flexible mortar
  2. Install tile with wider grout joints
  3. Use a thinner tile
  4. Stiffen the floor structure to meet deflection criteria Correct answer.

Explanation

Excessive deflection must be corrected structurally, typically by stiffening the floor, before tile is installed. Flexible mortar or wider joints cannot compensate for structural movement beyond the allowable limit.

Question 25Substrate Preparation and Evaluation

What is the purpose of a mock-up or test panel during substrate evaluation?

  1. To select the grout color
  2. To verify the installation system performs on the actual substrate Correct answer.
  3. To measure the room's square footage
  4. To determine the tile's retail price

Explanation

A mock-up confirms that the chosen adhesive, membrane, and tile system bond and perform properly on the actual substrate and site conditions. It is a performance check, not a pricing or design step.

Question 26Substrate Preparation and Evaluation

When preparing a substrate for large format tile, which condition must be addressed because it can prevent the mortar from achieving a proper bond?

  1. A surface with a slight texture for mechanical key
  2. A surface that has been properly primed
  3. A surface that is clean, sound, and free of contaminants
  4. A surface that is dusty or has loose material Correct answer.

Explanation

Mortar bonding requires direct contact with a clean, sound substrate. Dust, dirt, or loose material acts as a bond breaker and must be removed before tile installation. A textured or primed surface is generally acceptable or beneficial.

Question 27Substrate Preparation and Evaluation

A concrete slab on grade is being evaluated for large format tile. The slab has no vapor retarder beneath it and shows high moisture readings. Which substrate preparation is most appropriate?

  1. Etch the slab with acid to open the pores
  2. Apply a surface-applied moisture mitigation system Correct answer.
  3. Install tile directly with a standard thin-set mortar
  4. Wait 24 hours after the last rain before tiling

Explanation

Without a vapor retarder, moisture can migrate through the slab and affect the tile assembly. A moisture mitigation system reduces vapor transmission to an acceptable level. Acid etching or short waits do not address ongoing vapor movement.

Question 28Substrate Preparation and Evaluation

A 10-foot straightedge placed on a concrete floor shows a 1/4-inch gap in the center. According to typical large format tile installation guidelines, what does this indicate?

  1. The floor is too flat and needs roughening
  2. The floor exceeds flatness tolerance and requires flattening Correct answer.
  3. The floor is within flatness tolerance for large format tile
  4. The floor requires grinding down the high edges

Explanation

Large format tile generally requires the substrate to be flat within 1/8 inch in 10 feet. A 1/4-inch gap exceeds that tolerance and must be corrected, typically with a self-leveling underlayment or patching compound. Grinding edges does not fix a center depression.

Question 29Substrate Preparation and Evaluation

Why is it important to verify the deflection of a wood subfloor before installing large format tile?

  1. To confirm the subfloor can resist bending under load Correct answer.
  2. To check that the subfloor has a vapor barrier
  3. To ensure the subfloor is clean and free of dust
  4. To measure the moisture content of the wood

Explanation

Deflection is the amount a floor bends under load. Excessive deflection can cause tile or grout cracking, especially with large format tile. Verifying deflection ensures the structure is stiff enough for the tile assembly.

Question 30Substrate Preparation and Evaluation

An installer is preparing a substrate that has a bond-breaking contaminant which cannot be fully removed. What is the most appropriate action?

  1. Apply a primer and tile directly over the contaminant
  2. Scarify the surface lightly and tile immediately
  3. Install a cleavage membrane or unbonded system over the area Correct answer.
  4. Proceed with installation using a premium thin-set mortar

Explanation

When a contaminant cannot be removed, direct bonding is unreliable. A cleavage membrane or unbonded system isolates the tile from the compromised substrate. Primers or premium mortars do not overcome a bond-breaking layer.

Question 31Materials, Mortars, and Adhesives

For large format tile installation, which mortar type is specifically designed to provide improved coverage and support for tile with at least one edge 15 inches or greater?

  1. Large and heavy tile mortar meeting ANSI A118.15 Correct answer.
  2. Epoxy adhesive meeting ANSI A118.3
  3. Thin-set mortar meeting ANSI A118.4
  4. Mastic adhesive meeting ANSI A136.1

Explanation

ANSI A118.15 covers improved modified dry-set cement mortar, often called large and heavy tile (LHT) mortar, formulated to reduce slump and improve coverage for large format tile. Standard thin-set (A118.4) may not provide adequate support. Mastic and epoxy are not intended for this purpose.

Question 32Materials, Mortars, and Adhesives

When mixing mortar for large format tile, what is the primary reason for following the manufacturer's specified water ratio and mixing time?

  1. To reduce the amount of mortar needed for coverage
  2. To prevent the mortar from staining the tile surface
  3. To ensure the mortar reaches its stated performance properties Correct answer.
  4. To achieve the proper consistency for easy spreading

Explanation

Mortar manufacturers formulate products to achieve specific performance characteristics when mixed with the correct amount of water and mixed for the specified duration. Deviating from these instructions can compromise properties such as bond strength, open time, and sag resistance. Consistency and coverage are secondary effects.

Question 33Materials, Mortars, and Adhesives

What is the minimum recommended mortar coverage for dry areas when installing large format tile?

  1. 80% Correct answer.
  2. 100%
  3. 50%
  4. 95%

Explanation

The Tile Council of North America (TCNA) recommends a minimum of 80% mortar coverage in dry areas for large format tile, with all edges and corners supported. Wet areas require 95% coverage. These requirements help prevent lippage and ensure bond strength.

Question 34Materials, Mortars, and Adhesives

Which trowel notch size is typically recommended for installing large format tile with a large and heavy tile mortar?

  1. 1/2 in. x 1/2 in. square notch Correct answer.
  2. 1/4 in. x 1/4 in. square notch
  3. 1/4 in. x 3/8 in. square notch
  4. 3/16 in. V-notch

Explanation

Large format tile generally requires a larger notch trowel, such as 1/2 in. x 1/2 in. square notch, to achieve adequate mortar coverage and support. Smaller notches may not provide enough mortar to fill the larger area and ensure proper contact.

Question 35Materials, Mortars, and Adhesives

What is the primary function of a crack isolation membrane when installing large format tile?

  1. To increase the bond strength of the mortar
  2. To reduce the weight of the tile installation
  3. To provide a slip-resistant surface
  4. To isolate the tile from substrate cracks Correct answer.

Explanation

Crack isolation membranes are designed to prevent cracks in the substrate from reflecting through the tile. They are especially important for large format tile, which is more susceptible to cracking from substrate movement. They do not provide slip resistance, increase bond strength, or reduce weight.

Question 36Materials, Mortars, and Adhesives

Which type of mortar is suitable for installing large format tile over a concrete substrate that has cured for at least 28 days?

  1. Epoxy mortar meeting ANSI A118.3
  2. Cement grout
  3. Organic adhesive meeting ANSI A136.1
  4. Latex-portland cement mortar meeting ANSI A118.4 Correct answer.

Explanation

Latex-portland cement mortar (ANSI A118.4) is commonly used for large format tile over properly cured concrete. Epoxy mortar is specialty, organic adhesive is not for large format, and cement grout is not an adhesive.

Question 37Materials, Mortars, and Adhesives

What is the purpose of back-buttering large format tile?

  1. To fill the tile joints
  2. To level the substrate
  3. To ensure full mortar coverage on the tile back Correct answer.
  4. To speed up the installation process

Explanation

Back-buttering involves applying a thin layer of mortar to the back of the tile to improve coverage and bond, especially important for large format tile. It helps fill voids and ensures proper contact with the troweled mortar on the substrate.

Question 38Materials, Mortars, and Adhesives

Which of the following is a key consideration when selecting a grout for large format tile with narrow joints?

  1. The grout must match the tile color exactly
  2. The grout must be epoxy-based for all installations
  3. The grout must be unsanded to penetrate narrow joints Correct answer.
  4. The grout must be sanded to fill wide joints

Explanation

For narrow joints (typically less than 1/8 in.), unsanded grout is recommended because sand particles can prevent proper penetration and compaction. Sanded grout is for wider joints. Epoxy grout can be used but is not mandatory, and color matching is aesthetic.

Question 39Materials, Mortars, and Adhesives

When installing large format tile over a wood subfloor, which of the following is required to minimize deflection?

  1. A cement backer board installed with thin-set
  2. A double-layer wood subfloor with a total thickness of at least 1-1/8 in. Correct answer.
  3. A minimum of 1/2 in. plywood underlayment
  4. A waterproof membrane

Explanation

For large format tile over wood, the subfloor must be stiff enough to limit deflection; typically a double-layer wood subfloor with a total thickness of at least 1-1/8 in. is required. A single layer of plywood or backer board alone may not provide sufficient stiffness. Waterproofing is separate.

Question 40Materials, Mortars, and Adhesives

What is the primary reason for using a large and heavy tile mortar instead of a standard thin-set mortar for large format tile?

  1. It has a longer open time
  2. It dries faster
  3. It is less expensive
  4. It provides better sag resistance and coverage Correct answer.

Explanation

Large and heavy tile (LHT) mortars are formulated to resist sag and provide improved coverage, which is critical for heavy tile that may slump or have voids. They are not necessarily cheaper or faster-drying.

Question 41Materials, Mortars, and Adhesives

When mixing mortar, what is the consequence of adding too much water?

  1. Improved freeze-thaw resistance
  2. Reduced shrinkage
  3. Increased bond strength
  4. Decreased compressive strength Correct answer.

Explanation

Excess water increases porosity and reduces the compressive strength of the cured mortar. It can also lead to shrinkage, reduced bond strength, and other issues. Therefore, measuring water accurately is essential.

Question 42Materials, Mortars, and Adhesives

Which of the following is a characteristic of a non-sag mortar?

  1. It is only suitable for floor installations
  2. It can be applied vertically without slumping Correct answer.
  3. It has a very short pot life
  4. It requires the addition of a latex additive

Explanation

Non-sag mortar is designed to resist sagging or slumping when applied vertically, making it suitable for wall installations. It does not necessarily require a latex additive, is not limited to floors, and pot life varies.

Question 43Materials, Mortars, and Adhesives

What is the recommended method for measuring mortar coverage on a large format tile installation?

  1. Visual inspection after the tile is set
  2. Measuring the trowel notch depth
  3. Using a coverage chart
  4. Lifting a tile periodically and checking the back Correct answer.

Explanation

The most reliable way to verify coverage is to periodically lift a tile that has just been set and check the back for mortar transfer. This helps identify voids and ensures proper coverage. Visual inspection after setting is not sufficient, and charts or notch depth do not guarantee actual coverage.

Question 44Materials, Mortars, and Adhesives

Which of the following is a suitable substrate for direct bonding of large format tile with thin-set mortar?

  1. Particleboard
  2. Vinyl flooring
  3. Cured concrete Correct answer.
  4. Oriented strand board (OSB)

Explanation

Cured concrete is a suitable substrate for thin-set bonding of large format tile, provided it is clean, sound, and properly prepared. Particleboard, vinyl, and OSB are not suitable due to dimensional instability and poor bonding.

Question 45Materials, Mortars, and Adhesives

What is the purpose of a primer when applying a liquid waterproofing membrane before large format tile installation?

  1. To provide a slip-resistant surface
  2. To accelerate the curing of the membrane
  3. To improve adhesion of the membrane to the substrate Correct answer.
  4. To fill cracks in the substrate

Explanation

Primers are used to enhance the bond between the waterproofing membrane and the substrate, especially on porous or smooth surfaces. They do not fill cracks, provide slip resistance, or accelerate curing.

Question 46Materials, Mortars, and Adhesives

When installing large format tile with a cementitious mortar, what is the recommended minimum open time (working time) before the mortar surface skins over?

  1. 30 minutes
  2. 20 minutes Correct answer.
  3. 10 minutes
  4. 5 minutes

Explanation

Most cementitious mortars have an open time of about 20 minutes, meaning the mortar remains workable and can be troweled and covered with tile within that time. Open time varies by product, but 20 minutes is typical. If the mortar skins over, it should be removed and replaced.

Question 47Materials, Mortars, and Adhesives

Which type of mortar is most resistant to freeze-thaw cycling in exterior large format tile installations?

  1. Latex-modified mortar
  2. Mastic adhesive
  3. Standard thin-set mortar
  4. Epoxy mortar Correct answer.

Explanation

Epoxy mortar has low water absorption and high strength, making it highly resistant to freeze-thaw damage. Latex-modified mortars offer some freeze-thaw resistance but are not as durable as epoxy. Mastic is not suitable for exterior use.

Question 48Materials, Mortars, and Adhesives

What is the function of an anti-fracture membrane in a tile installation?

  1. To prevent water infiltration
  2. To increase the bond strength of the mortar
  3. To provide sound insulation
  4. To isolate the tile from minor substrate cracks Correct answer.

Explanation

Anti-fracture membranes are designed to isolate the tile from minor cracks in the substrate, preventing them from reflecting through the tile. They are not primarily for waterproofing, bond strength, or sound insulation.

Question 49Materials, Mortars, and Adhesives

When installing large format tile over a cured concrete slab, what is the maximum allowable moisture vapor emission rate (MVER) for most thin-set mortars unless a specific membrane is used?

  1. 10 lbs/1000 sq ft/24 hr
  2. 7 lbs/1000 sq ft/24 hr
  3. 5 lbs/1000 sq ft/24 hr Correct answer.
  4. 3 lbs/1000 sq ft/24 hr

Explanation

Most thin-set mortars can tolerate a maximum MVER of 5 lbs/1000 sq ft/24 hr. Higher emission rates require a moisture mitigation system. This limit helps prevent bond failure and efflorescence.

Question 50Materials, Mortars, and Adhesives

Which of the following is a key advantage of using a lightweight mortar for large format tile?

  1. It reduces the weight of the installation Correct answer.
  2. It has a longer pot life
  3. It is more resistant to freeze-thaw
  4. It requires less mixing water

Explanation

Lightweight mortars are formulated with lightweight aggregates, reducing the overall weight of the installation without sacrificing performance. This can be beneficial for large format tile on walls or elevated slabs. They do not necessarily have longer pot life, better freeze-thaw resistance, or require less water.