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CPC31320 Wall & Floor Tiling study materials
CPC31320 Wall & Floor Tiling study resources

CPC31320 Wall & Floor Tiling practice questions

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Question 1Core units of competency (construction industry common skills and wall and floor tiling)

Which document sets out the minimum legal requirements for safe work systems, consultation and hazard management on an Australian construction site?

  1. The manufacturer's tile adhesive data sheet
  2. The Australian Standard for ceramic tile installation
  3. The relevant work health and safety legislation and regulations Correct answer.
  4. The project architectural drawing set

Explanation

Work health and safety legislation and its regulations establish the legal duties for safe systems of work, consultation, hazard identification and risk control that apply on every construction site. Other documents may support safety planning but do not create the primary legal duties.

Question 2Core units of competency (construction industry common skills and wall and floor tiling)

Under the hierarchy of control, which measure ranks highest for managing a hazard?

  1. Providing a written safe work procedure
  2. Eliminating the hazard at its source Correct answer.
  3. Placing warning signs near the hazard
  4. Requiring workers to wear personal protective equipment

Explanation

The hierarchy of control ranks controls from most to least effective, and elimination of the hazard sits at the top because the risk is removed entirely. Lower-order controls such as signage, procedures and PPE rely on human behaviour and only reduce exposure.

Question 3Core units of competency (construction industry common skills and wall and floor tiling)

A tiler must cut a large format porcelain tile. Which PPE is most appropriate for protecting the eyes during wet cutting on a bench saw?

  1. A dust mask only
  2. Safety glasses with side shields Correct answer.
  3. Hearing protection only
  4. Cotton work gloves

Explanation

Wet cutting produces flying chips and slurry spray, so eye protection with side shields is the primary control for the eyes. A dust mask, hearing protection and gloves protect other body areas but leave the eyes exposed.

Question 4Core units of competency (construction industry common skills and wall and floor tiling)

What is the main purpose of a site-specific safe work method statement for high-risk construction work?

  1. To confirm the project completion date
  2. To record the quantity of materials delivered to site
  3. To describe how the high-risk work will be done and how risks will be controlled Correct answer.
  4. To list the tradespeople's qualification certificates

Explanation

A safe work method statement sets out the work activity, the hazards, the risk controls and the sequence of steps for high-risk construction work. It must be available on site and be reviewed when circumstances change.

Question 5Core units of competency (construction industry common skills and wall and floor tiling)

Which action best demonstrates consultation with workers before a new tiling task begins?

  1. Discussing the task hazards and controls with the workers who will do the job Correct answer.
  2. Filing the procedure in the site office without discussion
  3. Posting the completed procedure on the site noticeboard after work starts
  4. Emails the procedure to the client's project manager

Explanation

Consultation requires giving workers a genuine opportunity to contribute before decisions are made about hazards and controls, because they have direct knowledge of the task. Simply distributing or filing a document afterwards does not meet that duty.

Question 6Core units of competency (construction industry common skills and wall and floor tiling)

A tiler notices a damaged electrical lead on a bench saw. What is the correct first response?

  1. Ask a workmate to hold the lead clear of the floor
  2. Tag the equipment out of service and report the defect Correct answer.
  3. Tape the damaged section and continue cutting
  4. Move the saw to another area and keep using it

Explanation

Damaged electrical leads must be isolated, tagged and reported so the equipment is not used until it is repaired and tested. Continuing to use faulty equipment exposes workers to electric shock, and makeshift repairs are not acceptable.

Question 7Core units of competency (construction industry common skills and wall and floor tiling)

Which statement correctly describes the purpose of an environmental management plan on a construction project?

  1. It replaces the need for work health and safety planning
  2. It identifies environmental risks and the controls for managing them on site Correct answer.
  3. It records the wages paid to subcontractors
  4. It guarantees the project will not receive any environmental complaints

Explanation

An environmental management plan identifies the environmental aspects and risks of the project and sets out the controls, monitoring and responsibilities for managing them. It operates alongside safety and quality planning rather than replacing them.

Question 8Core units of competency (construction industry common skills and wall and floor tiling)

During wet cutting, slurry is flowing towards a stormwater drain. What is the most appropriate control?

  1. Sweep the slurry into the drain quickly before it settles
  2. Ignore it because slurry is only water and stone dust
  3. Contain and collect the slurry so it does not enter the drainage system Correct answer.
  4. Dilute the slurry with clean water before it reaches the drain

Explanation

Slurry contains suspended solids and chemical residues that pollute waterways and can block drains, so it must be contained and disposed of correctly. Diluting or sweeping it into the drain transfers the pollution to the environment.

Question 9Core units of competency (construction industry common skills and wall and floor tiling)

Which is the most reliable way to confirm that a wall is plumb before tiling begins?

  1. Observe the wall from a distance by eye
  2. Tap the wall to listen for hollow spots
  3. Measure the wall length with a tape
  4. Check the surface with a spirit level in both vertical directions Correct answer.

Explanation

Plumb is a vertical condition, so it is checked with a spirit level held vertically and also checked across the face to detect twist or lean. Tapping, measuring length and visual inspection do not establish verticality accurately.

Question 10Core units of competency (construction industry common skills and wall and floor tiling)

What is the main reason for priming a porous substrate before applying tile adhesive?

  1. To control suction so the adhesive retains enough water to cure properly Correct answer.
  2. To make the substrate waterproof
  3. To colour the wall so tile joints are visible
  4. To increase the thickness of the adhesive bed

Explanation

Highly porous substrates absorb water from the adhesive too quickly, which reduces adhesion and curing, so a suitable primer balances suction. Priming does not provide waterproofing or alter bed thickness.

Question 11Core units of competency (construction industry common skills and wall and floor tiling)

A tiler is setting out a floor and wants to avoid narrow cut tiles at the walls. What is the best approach?

  1. Start with full tiles in one corner and let the cuts fall where they may
  2. Centre the layout so cut tiles at opposing walls are equal and not too narrow Correct answer.
  3. Lay tiles diagonally to hide all edge cuts
  4. Start from the doorway with a full tile and ignore the far wall

Explanation

Centring the layout distributes cuts equally to opposite walls, which looks balanced and avoids slivers that are difficult to cut and prone to failure. Starting from a corner or doorway often produces a very narrow cut at the far side.

Question 12Core units of competency (construction industry common skills and wall and floor tiling)

Which tool is used to check that a tiled floor is level across a large area?

  1. A notched trowel
  2. A long straightedge with a spirit level Correct answer.
  3. A rubber grout float
  4. A tile scribe

Explanation

A long straightedge combined with a spirit level reveals level and any deviation across the floor surface. The other tools listed are for adhesive application, cutting and grouting.

Question 13Core units of competency (construction industry common skills and wall and floor tiling)

What is the purpose of the notches in a trowel used for applying tile adhesive?

  1. To spread the adhesive to a controlled, even bed thickness Correct answer.
  2. To remove excess grout from joints
  3. To cut tiles to size
  4. To score the back of the tile for better grip

Explanation

The notch depth and spacing determine the ridges of adhesive, which collapse when the tile is pressed to form a consistent bed with good coverage. The trowel does not cut tiles, score tile backs or clean grout joints.

Question 14Core units of competency (construction industry common skills and wall and floor tiling)

When fixing tiles to a wall, what does the term 'back buttering' mean?

  1. Painting the back of the tile with a waterproof sealer
  2. Grouting the back of the tile to improve grip
  3. Applying a thin layer of adhesive to the back of the tile as well as the wall Correct answer.
  4. Wetting the back of the tile before fixing

Explanation

Back buttering means spreading adhesive on the reverse face of the tile in addition to the notched bed on the wall, which improves contact and coverage, especially for large or heavily profiled tiles. It is not a sealing, wetting or grouting operation.

Question 15Core units of competency (construction industry common skills and wall and floor tiling)

Why should tile adhesive that has started to skin over in the bucket not be used?

  1. It will change colour and stain the tile face
  2. It will increase the coverage rate of the adhesive
  3. It will set too slowly and delay the next trade
  4. A skin prevents proper bonding between the adhesive and the tile Correct answer.

Explanation

When adhesive skins, a dry film forms that prevents the fresh adhesive from wetting and bonding to the tile, leading to debonding. Re-mixing or adding water cannot restore the bond of skimmed adhesive.

Question 16Core units of competency (construction industry common skills and wall and floor tiling)

What is the correct sequence for grouting a newly tiled floor?

  1. Grout first, then apply adhesive to the edges
  2. Apply grout immediately after fixing tiles, then clean with a wet mop
  3. Seal the joints before grouting to prevent staining
  4. Allow adhesive to cure, apply grout, tool joints, clean with a damp sponge and then polish Correct answer.

Explanation

Grout should only be applied after the adhesive has cured sufficiently, then joints are filled and tooled, excess removed with a damp sponge and haze polished off. Grouting too early disturbs the tiles and weakens the bond.

Question 17Core units of competency (construction industry common skills and wall and floor tiling)

Which condition is most likely to cause efflorescence on a tiled surface?

  1. Cutting tiles with a dry saw
  2. Excessive foot traffic on the finished floor
  3. Using a darker coloured grout
  4. Moisture migrating through the substrate and drying at the surface Correct answer.

Explanation

Efflorescence is the migration of soluble salts to the surface carried by water, which then evaporates and leaves a white deposit. Foot traffic, grout colour and dry cutting do not cause salt deposits.

Question 18Core units of competency (construction industry common skills and wall and floor tiling)

A tiled wall shows hollow-sounding areas soon after installation. Which cause is most probable?

  1. Use of a coloured grout
  2. Grouting after the adhesive cured
  3. Cleaning the tiles with a damp sponge
  4. Insufficient adhesive coverage behind the tiles Correct answer.

Explanation

Drummy or hollow sounds indicate voids behind the tile where adhesive coverage is insufficient, so the tile is not fully supported. Grout colour, correct curing and cleaning do not create voids.

Question 19Core units of competency (construction industry common skills and wall and floor tiling)

What is the appropriate action when a tiler identifies that the substrate is not flat within the required tolerance?

  1. Proceed and rely on grout to fill the gaps
  2. Use larger tiles to bridge the uneven surface
  3. Increase the adhesive bed thickness to absorb the unevenness
  4. Bring the substrate to tolerance with a suitable levelling compound before tiling Correct answer.

Explanation

Substrates must be flat within tolerance so tiles are fully supported and lippage is controlled, so the correct action is to level the substrate first. Thick adhesive beds, larger tiles and grout cannot compensate for an out-of-tolerance surface.

Question 20Core units of competency (construction industry common skills and wall and floor tiling)

Which practice best reduces the risk of manual handling injury when carrying boxes of tiles?

  1. Lift with straight legs and a bent back
  2. Carry two boxes at once to reduce the number of trips
  3. Twist the torso to place the box on a high shelf
  4. Use a trolley or team lift and keep the load close to the body Correct answer.

Explanation

Mechanical aids or team lifting reduce the load on the body, and keeping the load close limits the strain on the spine. Twisting under load and lifting with a bent back increase injury risk.

Question 21Core units of competency (construction industry common skills and wall and floor tiling)

What is the purpose of a control joint in a large tiled floor area?

  1. To allow movement and reduce stress that could crack tiles or grout Correct answer.
  2. To mark the boundary between rooms
  3. To separate different tile colours for appearance
  4. To provide a drainage channel

Explanation

Control joints accommodate movement from thermal change, moisture and structural deflection, relieving stress that would otherwise crack tiles or grout. They are a movement provision, not a decorative or drainage feature.

Question 22Core units of competency (construction industry common skills and wall and floor tiling)

Which term describes the vertical misalignment between the edges of adjacent tiles?

  1. Crazing
  2. Efflorescence
  3. Lippage Correct answer.
  4. Delamination

Explanation

Lippage is the difference in height between adjacent tile edges, which is controlled by substrate flatness, adhesive bed and tile thickness. Crazing is fine surface cracking, efflorescence is salt deposit and delamination is separation of layers.

Question 23Core units of competency (construction industry common skills and wall and floor tiling)

Which statement best describes the role of a waterproofing membrane in a bathroom before tiling?

  1. It forms a continuous barrier that prevents water reaching the substrate Correct answer.
  2. It provides a decorative finish under the tiles
  3. It increases the structural strength of the wall
  4. It replaces the need for tile adhesive

Explanation

A waterproofing membrane creates a continuous barrier over the substrate and up the walls so that water cannot penetrate behind the tiles. It does not replace adhesive, provide decoration or add structural strength.

Question 24Core units of competency (construction industry common skills and wall and floor tiling)

A tiler is working at height on a mobile scaffold. Which control is essential before starting work?

  1. Confirm the scaffold is complete, inspected and tagged as safe to use Correct answer.
  2. Use a ladder leaning against the scaffold instead
  3. Remove the guardrails to make it easier to reach the wall
  4. Stand on the top rail to reach higher courses

Explanation

Scaffolding must be complete, inspected and tagged before use so that platforms, guardrails and access are in place. Removing guardrails, standing on rails or substituting an unsafe ladder defeats the purpose of the scaffold.

Question 25Core units of competency (construction industry common skills and wall and floor tiling)

Which document would a tiler consult to confirm the correct adhesive class for fixing porcelain tiles to a concrete wall?

  1. The project's traffic management plan
  2. The site diary
  3. The tile manufacturer's installation instructions and the relevant Australian Standard Correct answer.
  4. The purchase order for sand and cement

Explanation

Adhesive class selection depends on the tile type, substrate and service conditions, which are specified in manufacturer instructions and the relevant Australian Standard. Site diaries, purchase orders and traffic plans do not specify adhesive classification.

Question 26Core units of competency (construction industry common skills and wall and floor tiling)

Which unit of measurement is used to state the nominal size of a square tile?

  1. Litres
  2. Kilograms
  3. Square metres
  4. Millimetres Correct answer.

Explanation

Tile dimensions such as 300 by 300 are always quoted in millimetres, which is the standard linear unit on tile packaging and in specifications. Square metres describe coverage area rather than the size of a single tile.

Question 27Core units of competency (construction industry common skills and wall and floor tiling)

What does the abbreviation PPE stand for in construction work?

  1. Personal protective equipment Correct answer.
  2. Project planning estimate
  3. Permanent plant enclosure
  4. Pre-purchase evaluation

Explanation

PPE means personal protective equipment, the items worn by a worker such as safety glasses, gloves, hearing protection and respiratory masks. Employers must supply it and workers must use it as instructed.

Question 28Core units of competency (construction industry common skills and wall and floor tiling)

Which class of tile is generally recommended for use on floors in areas with heavy foot traffic?

  1. Class 5 Correct answer.
  2. Class 2
  3. Class 1
  4. Class 0

Explanation

Abrasion resistance classes run from 1 to 5, and Class 5 offers the highest resistance to wear. It suits commercial floors subject to constant heavy traffic, whereas the lower classes are intended for lighter domestic use.

Question 29Core units of competency (construction industry common skills and wall and floor tiling)

A tiler needs to cut a curved shape from a ceramic tile. Which tool is best suited to this task?

  1. A grout float
  2. A tile scribe and snap cutter
  3. A notched adhesive trowel
  4. A wet saw with a guided plunge and freehand feed Correct answer.

Explanation

Curved cuts require a cutting method that allows the tile to be fed along a marked curve, which a wet saw with a suitable blade and open table can achieve. A scribe and snap cutter only produces straight breaks along a scored line.

Question 30Core units of competency (construction industry common skills and wall and floor tiling)

What is the purpose of a spirit level when setting out wall tiles?

  1. To measure the thickness of the adhesive bed
  2. To check the hardness of the substrate
  3. To confirm that courses are horizontal and vertical Correct answer.
  4. To record the moisture content of the wall

Explanation

A spirit level contains a bubble vial that shows whether a surface is truly horizontal or vertical. Setting out the first course with a level ensures subsequent courses stay aligned and the joints remain true.

Question 31Core units of competency (construction industry common skills and wall and floor tiling)

Which type of adhesive is normally supplied as a two-part product that must be mixed before use?

  1. Ready-mixed dispersion adhesive
  2. Mastic tub adhesive
  3. Reactive resin adhesive Correct answer.
  4. Cement-based powder adhesive

Explanation

Reactive resin adhesives consist of a resin and a separate hardener that are blended on site, after which the chemical cure begins. This limits pot life and makes accurate mixing essential.

Question 32Core units of competency (construction industry common skills and wall and floor tiling)

Why is it important to keep walkways and access routes clear on a tiling site?

  1. To reduce trips, slips and blocked escape routes Correct answer.
  2. To lower the cost of the adhesive used
  3. To improve the appearance of the finished work
  4. To speed up the curing of the grout

Explanation

Clear access routes reduce the risk of slips, trips and falls and keep emergency exits usable. Housekeeping is a basic hazard control that protects everyone on site, not just the tiler.

Question 33Core units of competency (construction industry common skills and wall and floor tiling)

Which statement best describes the purpose of a job safety analysis before starting a tiling task?

  1. It identifies hazards and the controls for each step of the work Correct answer.
  2. It records the quantity of tiles delivered to site
  3. It calculates the final cost of the tiling contract
  4. It lists the client's preferred tile colours

Explanation

A job safety analysis breaks a task into steps, identifies the hazards at each step and documents the controls to be applied. It is a planning tool for safety, not a commercial or design record.

Question 34Core units of competency (construction industry common skills and wall and floor tiling)

A tiler is fixing large-format porcelain tiles to a wall. Which adhesive characteristic matters most for preventing slip of the tile during curing?

  1. Low water content of the adhesive
  2. High slip resistance of the adhesive Correct answer.
  3. Long open time of the adhesive
  4. High flexibility of the adhesive

Explanation

Heavy tiles tend to slide down the wall before the adhesive sets, so an adhesive classified as slip resistant or non-slip holds them in place. Open time and flexibility address different issues such as working time and movement.

Question 35Core units of competency (construction industry common skills and wall and floor tiling)

What is the correct way to store bags of cement-based tile adhesive on site?

  1. On a raised pallet in a dry, covered area Correct answer.
  2. In the same area as solvent-based products
  3. Outdoors with the tops of the bags open
  4. Stacked directly on a damp concrete slab

Explanation

Cement-based adhesive absorbs moisture from the air and from damp surfaces, which causes lumping and loss of strength. Raised, dry, covered storage keeps the powder usable and protects it from contamination.

Question 36Core units of competency (construction industry common skills and wall and floor tiling)

A tiler must lift a stack of tile boxes from floor level. Which technique best protects the back?

  1. Hold the load at arm's length and lift quickly
  2. Bend at the waist and twist while lifting
  3. Lift with straight legs and a rounded back
  4. Bend the knees, keep the load close and lift smoothly Correct answer.

Explanation

Bending the knees keeps the load close to the body and uses the leg muscles rather than the spine. Twisting or jerking while lifting greatly increases the strain on the lower back.

Question 37Core units of competency (construction industry common skills and wall and floor tiling)

Which action best controls silica dust when a tiler uses a dry cutter or grinder on tile?

  1. Wear a cap and safety glasses only
  2. Use water suppression or on-tool dust extraction Correct answer.
  3. Work faster to shorten exposure time
  4. Open a door to the rest of the building

Explanation

Respirable crystalline silica is released when tile or concrete is cut dry, and it damages the lungs. Water suppression or extraction at the tool captures dust at its source, which is far more effective than general ventilation.

Question 38Core units of competency (construction industry common skills and wall and floor tiling)

Which substrate condition must be confirmed before tiling over a new sand-cement screed?

  1. The screed surface is still wet to the touch
  2. The screed has cured and reached a suitable moisture level Correct answer.
  3. The screed has been polished to a shine
  4. The screed contains no sand

Explanation

A new screed holds construction moisture that must dry out before tiling, otherwise trapped moisture can debond the adhesive or cause efflorescence. The surface should be sound, clean and within the moisture limit stated by the adhesive manufacturer.

Question 39Core units of competency (construction industry common skills and wall and floor tiling)

A tiler is laying tiles over a timber floor. Which measure is most important to prevent tile cracking?

  1. Ensure the floor structure is stiff enough and fix a suitable underlay Correct answer.
  2. Lay the tiles directly onto the floorboards
  3. Use the cheapest available cement adhesive
  4. Increase the thickness of the grout lines

Explanation

Timber floors deflect under load, and movement is transferred to the brittle tile unless the structure is stiffened and a decoupling underlay is used. Adhesive alone cannot compensate for excessive deflection.

Question 40Core units of competency (construction industry common skills and wall and floor tiling)

What does a tile's water absorption rating mainly indicate?

  1. How well the tile conducts heat
  2. How much weight the tile can support
  3. How resistant the glaze is to scratching
  4. How porous the tile body is and how much water it can take in Correct answer.

Explanation

Water absorption is measured as a percentage of the tile's dry weight and reflects the porosity of the body. Low-absorption tiles such as porcelain are dense and need adhesives designed for them, while high-absorption tiles are more porous.

Question 41Core units of competency (construction industry common skills and wall and floor tiling)

Which practice best prevents lippage when fixing large-format floor tiles?

  1. Press each tile down hard with the heel of the hand
  2. Lay tiles as quickly as possible without checking
  3. Use a levelling clip system and check each tile as it is laid Correct answer.
  4. Use a very wet adhesive mix

Explanation

Lippage is the difference in height between adjacent tile edges, and it is controlled by holding the tiles level while the adhesive sets. A clip or levelling system does this mechanically, and checking each tile catches problems early.

Question 42Core units of competency (construction industry common skills and wall and floor tiling)

A tiler is asked to fix tiles around a floor drain in a wet area. Which detail is essential?

  1. The tiles should be laid over the drain without sealing
  2. The drain should be raised above the tile surface
  3. The waterproofing must be continuous and dressed into the drain flange Correct answer.
  4. Grout should be omitted around the drain

Explanation

Waterproofing in a wet area must form a continuous barrier that laps into the drain flange so any water reaching the membrane drains away. Interrupting the membrane at the drain creates a path for leakage into the structure below.

Question 43Core units of competency (construction industry common skills and wall and floor tiling)

What is the main purpose of sealing a porous natural stone tile before grouting?

  1. To increase the weight of the tile
  2. To stop grout pigment staining the stone surface Correct answer.
  3. To speed up the setting of the adhesive
  4. To make the stone conduct heat better

Explanation

Porous stone such as travertine or limestone can draw pigment from the grout into its surface, causing permanent staining. A suitable impregnating sealer fills the surface pores so the grout sits on top and can be cleaned off.

Question 44Core units of competency (construction industry common skills and wall and floor tiling)

A tiler finds a hairline crack running across a concrete floor slab that is to be tiled. What is the most appropriate response?

  1. Increase the tile size to hide the crack
  2. Report it and confirm whether a crack isolation membrane is required Correct answer.
  3. Tile straight over the crack without comment
  4. Fill the crack with grout and continue

Explanation

Cracks in a slab can widen and transfer movement into the tiled finish, so they must be assessed rather than covered up. A crack isolation membrane or structural repair may be specified, and the decision belongs with the supervisor or designer.

Question 45Core units of competency (construction industry common skills and wall and floor tiling)

Which factor most strongly governs how long a cement-based adhesive remains workable in the bucket?

  1. The number of tiles in the room
  2. The width of the grout joints
  3. The colour of the tile being fixed
  4. The ambient temperature and the mix ratio Correct answer.

Explanation

Cement adhesives set by chemical hydration, which proceeds faster in hot conditions and can be altered by adding extra water. The manufacturer's mix ratio and the site temperature therefore determine pot life and open time.

Question 46Core units of competency (construction industry common skills and wall and floor tiling)

A tiler is asked to lay tiles in a pattern where joints must align across two adjoining rooms. Which setting-out approach best achieves this?

  1. Set out each room independently from its own centre
  2. Establish a single grid datum that carries through both doorways Correct answer.
  3. Lay the second room first and work backwards
  4. Start each room from the nearest wall

Explanation

A continuous grid established from one datum ensures the joint lines meet exactly at the doorway and the pattern reads as one installation. Independent setting out in each room almost always produces a mismatch at the threshold.

Question 47Core units of competency (construction industry common skills and wall and floor tiling)

A newly grouted floor shows patchy colour variation across the joints. Which cause is most likely?

  1. Leaving the grout to cure for the full period
  2. Choosing tiles with a matt finish
  3. Inconsistent mixing water and uneven washing of the joints Correct answer.
  4. Using too many spacers in the joints

Explanation

Cement grouts are sensitive to the amount of mixing water and to how much is removed during washing. Too much water in one batch or uneven washing leaves different densities and pigment levels, which dry to different shades.

Question 48Core units of competency (construction industry common skills and wall and floor tiling)

A tiled wall sounds solid when tapped but shows a fine crack running along a grout joint after several months. Which explanation is most consistent with these observations?

  1. The adhesive was mixed with too little water
  2. Movement in the substrate has been transferred through a rigid joint Correct answer.
  3. The grout was applied too soon after fixing
  4. The tiles were fixed with the wrong trowel size

Explanation

A solid bed rules out widespread debonding, and a crack following a joint points to movement rather than a fixing fault. Rigid joints cannot accommodate substrate or thermal movement, so a movement or control joint is needed at the appropriate spacing.

Question 49Core units of competency (construction industry common skills and wall and floor tiling)

A tiler is asked to tile an external wall in a cold climate. Which combination of choices is most appropriate?

  1. Porous tiles with wide grout joints and no sealer
  2. Standard interior tiles with a ready-mixed adhesive
  3. Large-format tiles with no movement joints
  4. Frost-resistant tiles, a suitable adhesive and movement joints at the specified spacing Correct answer.

Explanation

External walls experience freeze-thaw cycling, thermal movement and rain, so the tile, adhesive and jointing system must all be rated for exterior use. Movement joints at the designed spacing allow the assembly to accommodate that movement without cracking.

Question 50Core units of competency (construction industry common skills and wall and floor tiling)

During a pull-off test on a tiled area, several tiles separate cleanly from the adhesive, leaving the adhesive bonded to the substrate. What does this indicate?

  1. Moisture trapped in the substrate
  2. Failure within the substrate itself
  3. Poor bond between the tile and the adhesive Correct answer.
  4. Correct installation with strong adhesion

Explanation

When the adhesive stays stuck to the substrate but releases from the tile, the weak link is the tile-to-adhesive interface. Causes include a dusty or unprimed tile back, an unsuitable adhesive or insufficient bedding pressure.