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NCCER Glazier practice questions

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Question 1Glazing Fundamentals and Safety

A glazier is about to set a large insulated glass unit into a storefront frame. Which personal protective equipment is most important for protecting the hands while handling the lites?

  1. Disposable latex gloves
  2. Cut-resistant gloves Correct answer.
  3. Welding gauntlets
  4. Rubber insulating gloves

Explanation

Glass edges cause lacerations, so cut-resistant gloves are the standard hand protection for handling lites and debris. They balance abrasion and cut protection with enough dexterity to control the glass.

Question 2Glazing Fundamentals and Safety

Before cutting laminated glass with a hand cutter, what is normally applied along the intended score line?

  1. A coat of primer
  2. Cutting oil or lubricant Correct answer.
  3. A strip of masking tape only
  4. A bead of silicone sealant

Explanation

Lubricating the score line helps the cutter wheel run smoothly and produces a cleaner, more consistent score that breaks reliably. Dry scoring on laminated glass increases the chance of a ragged break or wheel chatter.

Question 3Glazing Fundamentals and Safety

Which glass type is produced by heating annealed glass and then rapidly cooling it so it breaks into small, granular pieces?

  1. Heat-strengthened glass
  2. Wire glass
  3. Laminated glass
  4. Tempered glass Correct answer.

Explanation

Tempered glass is heat-treated and rapidly quenched, which puts the surfaces in high compression so the pane fractures into small relatively safe fragments. Heat-strengthened glass is cooled more slowly and breaks into larger shards.

Question 4Glazing Fundamentals and Safety

What is the primary purpose of the interlayer in laminated glass?

  1. To increase the visible light transmission
  2. To reduce the weight of the unit
  3. To provide the color tint in tinted glass
  4. To hold the fragments together after breakage Correct answer.

Explanation

The plastic interlayer bonds the glass lites so that, when broken, the fragments adhere to it instead of falling free. This is why laminated glass is used in overhead glazing and safety applications.

Question 5Glazing Fundamentals and Safety

A glazier must lift a heavy glass lite by hand. Which practice best reduces the risk of back injury?

  1. Twist the torso while lifting to clear the frame
  2. Reach out at arm's length to gain leverage
  3. Keep the load close and lift with the legs Correct answer.
  4. Lift with straight legs and a bent back

Explanation

Keeping the load close to the body and using the leg muscles to lift reduces strain on the lower back. Twisting or reaching away from the body increases the lever arm and the risk of injury.

Question 6Glazing Fundamentals and Safety

Which tool is used to remove excess sealant and smooth a glazing bead joint?

  1. A suction cup lifter
  2. A sealant tool or spatula Correct answer.
  3. A putty knife with a sharp edge
  4. A glass cutter

Explanation

A sealant tool has a shaped edge that tools the bead to a uniform profile and removes excess material cleanly. Sharp putty knives can score or damage glass and do not produce a consistent bead.

Question 7Glazing Fundamentals and Safety

What does the term 'daylight opening' refer to in a storefront system?

  1. The working hours when glazing is permitted
  2. The clear glass area visible after glazing Correct answer.
  3. The gap between the frame and the rough opening
  4. The opening left for a door closer

Explanation

The daylight opening is the visible clear area of glass bounded by the frame or stops. It is used for glass sizing, code checks, and estimating visible glass area.

Question 8Glazing Fundamentals and Safety

A glazier is working on a scaffold platform. What is the minimum requirement for the platform's guardrail system?

  1. A single top rail only
  2. A rope line at waist height
  3. A warning sign posted at the base
  4. A top rail, mid rail, and toe board Correct answer.

Explanation

Guardrail systems on scaffolds require a top rail, a mid rail, and toe boards to prevent both falls and dropped objects. A single rail or a rope does not meet the fall-protection requirement.

Question 9Glazing Fundamentals and Safety

A glazier is setting a lite into a frame and must maintain a uniform gap between the glass edge and the frame. Which component is normally used to control this gap?

  1. Glazing tape alone
  2. Backer rod alone
  3. Setting blocks and edge clearance spacers Correct answer.
  4. Silicone sealant alone

Explanation

Setting blocks carry the weight of the lite and spacers maintain edge clearance so the glass does not bear directly on the frame. Sealant and tape seal the joint but do not establish the structural clearance.

Question 10Glazing Fundamentals and Safety

Why must a tempered glass lite never be cut, drilled, or edge-ground after tempering?

  1. The interlayer prevents cutting tools from penetrating
  2. The treatment stresses the glass, so any disruption can shatter it Correct answer.
  3. The glass becomes too hard for any tool to cut
  4. The glass is coated and would lose its coating

Explanation

Tempering puts the glass in a balanced state of internal stress, and cutting or drilling releases that balance and can cause the lite to shatter. All fabrication must be completed before the glass is tempered.

Question 11Glazing Fundamentals and Safety

What is the purpose of a weep hole or drainage slot in a storefront sill?

  1. To provide a passage for wiring
  2. To allow the glass to expand upward
  3. To allow water to drain from the glazing pocket Correct answer.
  4. To allow air to enter the building

Explanation

Weep holes let water that enters the glazing pocket drain to the exterior so it does not sit against the glass or sealant. Blocked or missing weep holes are a common cause of water infiltration.

Question 12Glazing Fundamentals and Safety

A glazier is using a suction cup lifter to carry a large lite. What check is most important before lifting?

  1. Checking the color match of the glass
  2. Verifying the cups seal and hold vacuum on the glass Correct answer.
  3. Measuring the glass thickness with calipers
  4. Confirming the glass is clean of all labels

Explanation

A suction lifter depends on a reliable vacuum seal, so the cups must be checked for seal and grip before the load is lifted. A failed seal can drop the lite without warning.

Question 13Glazing Fundamentals and Safety

Which sealant type is typically specified for structural glazing where the sealant must transfer wind load from the glass to the frame?

  1. Latex caulk
  2. Structural silicone sealant Correct answer.
  3. Butyl glazing tape
  4. Oil-based putty

Explanation

Structural silicone is formulated to bond glass to metal and carry structural loads such as wind pressure. Non-structural sealants and tapes provide weather sealing but are not designed to transfer loads.

Question 14Glazing Fundamentals and Safety

When glazing an insulating glass unit, why must the edge seal of the unit be kept out of continuous standing water?

  1. Water changes the color of the low-E coating
  2. Water prevents the glass from expanding
  3. Water increases the unit's weight beyond the frame capacity
  4. Water can degrade the edge seal and cause fogging between the lites Correct answer.

Explanation

The perimeter edge seal of an insulating unit is vulnerable to prolonged water contact, which can break down the seal and allow moisture to fog the cavity. Proper drainage and weep holes keep the edge seal from sitting in water.

Question 15Glazing Fundamentals and Safety

A worker must break off a scored piece of glass. Which technique is safest?

  1. Snap the glass quickly over the knee
  2. Score the opposite side and twist
  3. Strike the score line sharply with a hammer
  4. Apply steady bending pressure away from the score while supporting both sides Correct answer.

Explanation

Running a score relies on controlled bending that propagates the crack along the score line while both halves are supported. Striking or twisting produces uncontrolled breaks and flying fragments.

Question 16Glazing Fundamentals and Safety

Which condition would most likely require the use of a fall-arrest system rather than a guardrail system?

  1. Working on a completed sidewalk with barricades
  2. Working at ground level beside a storefront
  3. Working at height where a guardrail cannot be installed Correct answer.
  4. Working inside a fully enclosed building

Explanation

When guardrails cannot be provided, an approved fall-arrest system such as a harness and lanyard is required to protect workers at height. Ground-level or fully enclosed work does not present a fall hazard requiring arrest.

Question 17Glazing Fundamentals and Safety

What is the function of a glazing stop in a curtain wall system?

  1. To provide thermal insulation to the frame
  2. To retain the glass in the frame and cover the glazing pocket Correct answer.
  3. To anchor the frame to the structure
  4. To carry the dead load of the glass

Explanation

The glazing stop holds the lite against the frame and covers the pocket, often with a gasket or sealant. Dead load is carried by setting blocks, not by the stop.

Question 18Glazing Fundamentals and Safety

A glazier notices a small chip on the edge of a tempered lite just before installation. What is the appropriate action?

  1. Reject the lite and replace it Correct answer.
  2. Fill the chip with clear epoxy
  3. Grind the chip smooth with a sander
  4. Install it and cover the chip with sealant

Explanation

Edge damage on tempered glass concentrates stress and can cause spontaneous breakage, so a damaged lite should be rejected. Field repair of tempered edges is not permitted because any grinding disrupts the temper.

Question 19Glazing Fundamentals and Safety

Which document typically specifies the required glass thickness, type, and glazing accessories for a project?

  1. The daily job hazard analysis
  2. The safety data sheets for sealants
  3. The glazing specifications and approved shop drawings Correct answer.
  4. The project schedule

Explanation

Glazing specifications and approved shop drawings define the glass type, thickness, and accessory requirements that the installer must follow. Safety data sheets and schedules serve other purposes.

Question 20Glazing Fundamentals and Safety

A glazier is installing a heavy lite and must move it laterally along a wall. Which aid best protects both the worker and the glass?

  1. Rolling it on its edge across the floor
  2. Carrying it by the edges with bare hands
  3. Dragging it on a blanket across the floor
  4. A glass dolly or vacuum lifter suited to the lite's weight Correct answer.

Explanation

Mechanical aids such as a glass dolly or rated vacuum lifter reduce strain and control the load during lateral movement. Carrying by the edges or dragging risks injury and edge damage.

Question 21Glazing Fundamentals and Safety

In a dry-glazed system, what component provides the weather seal between the glass and the frame?

  1. A setting block
  2. A compression gasket Correct answer.
  3. A backer rod only
  4. A weep hole

Explanation

Dry glazing uses compression gaskets that are squeezed against the glass to form the weather seal. Setting blocks carry weight and weep holes drain water, but neither seals the joint.

Question 22Glazing Fundamentals and Safety

A glazier is evaluating why a newly installed storefront leaks during rain. Which factor is most likely to be the cause?

  1. Missing or blocked weep holes in the sill Correct answer.
  2. Setting blocks placed at the quarter points
  3. A low-E coating on the glass
  4. Glass that is slightly thicker than specified

Explanation

Water that enters the glazing pocket must drain through weep holes; if they are missing or blocked, water backs up and leaks inside. Correct setting block placement and coating choice do not cause leakage.

Question 23Glazing Fundamentals and Safety

A glazing crew must install glass in a curtain wall where the specified structural silicone has a cure time of 21 days before load transfer. What is the correct interpretation for scheduling?

  1. The units can be shipped the same day the silicone is applied
  2. The silicone can carry design wind load immediately after tooling
  3. The cure time applies only to the sealant color match
  4. The glazed units must remain supported until the silicone reaches full cure Correct answer.

Explanation

Structural silicone must cure to develop its design strength, so units need temporary support until the specified cure period is reached. Handling or loading the units early can fail the bond.

Question 24Glazing Fundamentals and Safety

A glazier is choosing between heat-strengthened and tempered glass for a sloped overhead application. Which reasoning is most defensible?

  1. Either glass type eliminates the need for a laminated interlayer overhead
  2. Tempered glass cannot be used overhead because it is too strong
  3. Tempered glass is preferred because its break pattern reduces injury risk from falling fragments Correct answer.
  4. Heat-strengthened glass is preferred because it breaks into smaller granules

Explanation

Overhead glazing demands a break pattern that limits injury, and tempered glass fractures into small granules rather than large shards. Laminated glass is often also required, but the break-pattern reasoning favors tempered over heat-strengthened.

Question 25Glazing Fundamentals and Safety

During a site inspection, a glazier finds that setting blocks were placed at the corners of an insulating glass unit. Why is this placement a problem?

  1. Corner placement concentrates load where the edge seal is weakest and can damage the unit Correct answer.
  2. Corner blocks prevent the gasket from compressing
  3. Corner blocks interfere with the weep holes
  4. Corner blocks prevent the glass from being cleaned

Explanation

Setting blocks should be located away from the corners, typically at the quarter points, because corner placement concentrates load on the vulnerable edge seal of an insulating unit. This can crack the glass or break the seal.

Question 26Glazing Fundamentals and Safety

When handling a large glass lite manually, which practice best protects the glazier from cuts?

  1. Gripping the lite by its edges to control the direction of the glass
  2. Wearing cut-resistant gloves and long sleeves while keeping hands away from the glass edges Correct answer.
  3. Carrying the lite with bare hands to maintain a better feel for the glass
  4. Holding the lite against the body to reduce the leverage on the arms

Explanation

Cut-resistant gloves and long sleeves protect the hands and forearms from the sharp edges of glass, and keeping hands away from the edges prevents contact with the most hazardous part of the lite. Gripping the edges or carrying with bare hands exposes skin directly to those edges, and holding glass against the body increases the risk of a serious cut if the lite breaks.

Question 27Glazing Fundamentals and Safety

What is the primary purpose of a safety data sheet (SDS) for a glazing sealant or primer?

  1. To provide the cure time and application temperature for the product
  2. To list the project locations where the product has been approved
  3. To specify the structural capacity of the sealant joint
  4. To communicate the hazards, safe handling, and emergency measures for the product Correct answer.

Explanation

An SDS is a hazard-communication document that gives workers information on the health and physical hazards of a chemical product, safe handling practices, and first-aid and spill-response measures. Cure time, structural capacity, and project approvals are found in technical data sheets or project specifications, not in the SDS.

Question 28Glazing Fundamentals and Safety

Before using a cut-resistant glove around rotating or pulling machinery, what should a glazier confirm?

  1. That the glove is rated for the highest cut level available
  2. That the glove has a snug fit and no loose cuffs or torn material that could catch Correct answer.
  3. That the glove is made of the thickest material available
  4. That the glove is worn over a second pair for extra protection

Explanation

Gloves can be caught by rotating or pulling equipment, so a snug fit with no loose cuffs or torn material reduces the chance of entanglement and pull-in. Higher cut ratings, thickness, or layering do not address entanglement and can even increase the risk by making the glove bulkier or looser.

Question 29Glazing Fundamentals and Safety

Which glass type is intended to break into small, relatively blunt fragments when fractured?

  1. Heat-strengthened glass
  2. Tempered glass Correct answer.
  3. Laminated glass
  4. Annealed glass

Explanation

Tempered glass is heat-treated so that the surfaces are in high compression; when it breaks, the stored energy releases and the lite fractures into small, relatively blunt fragments. Annealed and heat-strengthened glass break into larger, sharper shards, and laminated glass holds together through its interlayer rather than fragmenting into small pieces.

Question 30Glazing Fundamentals and Safety

A crew needs to reach a second-floor storefront opening. Which practice is required before anyone works from the top rail of a stepladder?

  1. Prohibiting work from the top rail and providing a ladder tall enough to work from a lower step Correct answer.
  2. Having a second worker steady the ladder by hand
  3. Using a ladder that is rated for the combined weight of the worker and tools
  4. Tying off to the ladder with a personal fall-arrest system

Explanation

Ladder standards prohibit standing on the top cap or top step of a stepladder because there is no support above that point and balance is easily lost. The correct solution is to select a ladder tall enough that the worker can stand at or below the highest permitted step, not to tie off to the ladder or rely on a helper to steady it.

Question 31Glazing Fundamentals and Safety

A glazier is applying a low-modulus silicone sealant in a joint. What does low modulus describe about the sealant?

  1. It can accommodate more movement before the stress in the sealant becomes excessive Correct answer.
  2. It cures faster than a high-modulus sealant
  3. It has a lower tensile strength and is therefore unsuitable for exterior joints
  4. It has a lower cost per cartridge than high-modulus sealants

Explanation

Modulus describes the stress a sealant develops for a given amount of strain; a low-modulus sealant develops less stress as the joint moves, so it can accommodate greater movement. Cost, cure speed, and tensile strength are separate properties and do not define modulus.

Question 32Glazing Fundamentals and Safety

When installing a gasket in a dry-glazed system, what condition must the gasket channel be in before the gasket is pressed into place?

  1. Warmed with a torch to soften the gasket
  2. Filled with sealant to bed the gasket
  3. Coated with a release agent to prevent adhesion
  4. Clean and dry, with no debris or moisture in the channel Correct answer.

Explanation

A gasket must seat fully and uniformly to seal; debris or moisture in the channel prevents full seating and can create a leak path. Release agents, bedding sealant, and torch heating are not standard practices and can damage the gasket or interfere with its seal.

Question 33Glazing Fundamentals and Safety

Why must setting blocks under an insulating glass unit be located so that they do not block weep holes or drainage paths?

  1. So that water entering the sill can drain out instead of accumulating against the unit Correct answer.
  2. So that the blocks do not come into contact with the glass edge
  3. So that the unit can be shimmed to a level position
  4. So that the blocks can be removed after glazing is complete

Explanation

Weep holes and drainage paths exist to let water that enters the sill system escape to the exterior. If setting blocks obstruct them, water can pond in the sill and remain in contact with the edge seal of the insulating glass unit, which can lead to seal failure. The blocks are not removed later, are not used for leveling, and are intended to bear on the lower edge of the unit.

Question 34Glazing Fundamentals and Safety

A glazier is about to cut a lite of annealed glass. Which step should be taken first to prepare the work area?

  1. Set up a fan to blow dust away from the score line
  2. Score the glass while it is still in the shipping crate
  3. Place the glass on a flat, padded surface and confirm the cutting table is stable Correct answer.
  4. Apply cutting oil to the glass before placing it on the table

Explanation

Cutting requires a stable, padded surface that supports the glass and reduces the chance of breakage or slippage during scoring and snapping. Scoring in the crate, using a fan, or oiling before the glass is positioned does not establish the safe, supported work surface that cutting requires.

Question 35Glazing Fundamentals and Safety

Which statement correctly describes the load path of a curtain wall panel's dead load?

  1. The glass carries its own dead load directly to the mullion through the sealant
  2. The dead load is carried entirely by the glazing stops
  3. The dead load is transferred through the setting blocks to the frame and then to the building structure Correct answer.
  4. The dead load is transferred through the weather seal to the adjacent panels

Explanation

In a curtain wall, the weight of the glass is transferred through setting blocks into the frame, and the frame transfers it to the building structure. Sealant, glazing stops, and weather seals are not designed to carry the dead load of the glass.

Question 36Glazing Fundamentals and Safety

What is the main reason a glazier should never stand a lite on a hard floor without padding under its edge?

  1. The lite will become electrically charged
  2. The glass will scratch the floor finish
  3. The lite will absorb moisture through its edge
  4. The edge can chip or crack, weakening the lite and creating a sharp hazard Correct answer.

Explanation

Glass edges are vulnerable to chipping and cracking, and a damaged edge can weaken the lite and produce sharp fragments. Padding under the edge distributes the contact and protects the edge from impact with a hard floor. Floor scratching, moisture absorption, and static charge are not the primary concerns in this situation.

Question 37Glazing Fundamentals and Safety

A glazier is installing a heavy lite alone and needs to keep it from tipping while setting it into the frame. Which aid is most appropriate?

  1. A rope tied around the lite and anchored to a nearby column
  2. A second worker holding the lite by hand without a brace
  3. A wedge driven between the glass and the frame
  4. A temporary brace or setting aid that holds the lite in position while it is secured Correct answer.

Explanation

A temporary brace or setting aid supports the lite in position and reduces the chance of tipping while the glazier secures it. Hand-holding without a brace, wedging against the glass, and tying a rope around the lite are unsafe because they do not provide stable, controlled support and can damage the glass.

Question 38Glazing Fundamentals and Safety

A glazier must work near an open floor edge while installing glass. Which combination best reflects the hierarchy of fall protection?

  1. Rely on a personal fall-arrest system as the first choice in all cases
  2. Use a safety monitor to warn workers when they approach the edge
  3. Eliminate the exposure where possible, then use guardrails, then fall-arrest systems Correct answer.
  4. Use warning lines alone to keep workers away from the edge

Explanation

Fall protection follows a hierarchy: eliminate the exposure first, then use passive systems such as guardrails, and rely on personal fall-arrest systems only when the higher-level measures are not feasible. Warning lines and safety monitors are limited measures and do not replace guardrails or arrest systems where those are required.

Question 39Glazing Fundamentals and Safety

A glazier is reviewing a sealant joint design where the joint width is 1/2 inch and the expected movement is 25 percent. What does the 25 percent movement capability mean for the joint?

  1. The joint must be installed at one-quarter of its final width
  2. The sealant will cure to one-quarter of its original volume
  3. The sealant can stretch or compress by one-quarter of the joint width without failing Correct answer.
  4. The sealant loses one-quarter of its adhesion over time

Explanation

Movement capability is expressed as a percentage of the joint width that the sealant can accommodate in extension or compression while maintaining adhesion and cohesion. For a 1/2-inch joint, 25 percent means about 1/8 inch of movement in either direction, not a change in cure volume, installed width, or adhesion loss.

Question 40Glazing Fundamentals and Safety

During a pre-installation check of an insulating glass unit, the glazier notices that the primary seal appears intact but the secondary seal has a small void at one corner. What is the most appropriate action?

  1. Install the unit and note the void on the punch list for later repair
  2. Fill the void with a compatible sealant before installation
  3. Install the unit and rely on the primary seal to prevent moisture entry
  4. Reject the unit and request a replacement from the supplier Correct answer.

Explanation

The secondary seal is part of the unit's edge seal system and a void can compromise its performance and durability, so the unit should be rejected and replaced rather than field-repaired or installed with a known defect. Field-filling a void does not restore the factory seal, and relying on the primary seal alone ignores the role of the secondary seal.

Question 41Glass and Glazing Materials

Which glass type is produced by cooling molten glass quickly enough that it breaks into small, relatively blunt fragments instead of large sharp shards?

  1. Laminated glass
  2. Fully tempered glass Correct answer.
  3. Annealed glass
  4. Heat-strengthened glass

Explanation

Fully tempered glass is cooled rapidly through a controlled quench, which locks the surfaces in compression and the core in tension. This residual stress pattern makes the pane fracture into dense, granular fragments rather than large shards, which is why it qualifies as safety glazing.

Question 42Glass and Glazing Materials

A glazier must identify the plastic interlayer that bonds two glass plies into laminated glass. Which material is the standard interlayer?

  1. Polyvinyl butyral (PVB) Correct answer.
  2. Polyisocyanurate foam
  3. Silicone structural sealant
  4. Ethylene propylene diene monomer (EPDM)

Explanation

PVB is the conventional thermoplastic interlayer heat-and-pressure bonded between glass plies in laminated glass. It provides adhesion, fragment retention, and acoustic damping. EPDM and silicone are gasket and sealant materials, and polyisocyanurate is rigid insulation, none of which serve as a laminated interlayer.

Question 43Glass and Glazing Materials

What does the term "lite" mean in glazing terminology?

  1. A decorative etched pattern
  2. A single pane of glass in an assembly Correct answer.
  3. A spacer bar between panes
  4. A unit of luminous transmittance

Explanation

In glazing work, a lite is one individual pane or sheet of glass, regardless of thickness. A double-glazed unit therefore has two lites separated by a spacer. The term distinguishes the number of panes from the overall assembly.

Question 44Glass and Glazing Materials

Low-emissivity (low-E) coatings are applied to glass primarily to do which of the following?

  1. Increase visible light reflection to reduce glare
  2. Reduce radiant heat transfer through the glazing Correct answer.
  3. Prevent condensation on the interior surface
  4. Increase the glass's structural load capacity

Explanation

Low-E coatings are thin metallic oxide films that reflect long-wave infrared radiation, lowering radiant heat transfer and improving the unit's U-factor. They are largely transparent to visible light, so they do not primarily control glare or add structural strength.

Question 45Glass and Glazing Materials

Which glazing material is a transparent thermoplastic often used where impact resistance and light weight matter more than scratch resistance?

  1. Polycarbonate sheet Correct answer.
  2. Ceramic frit
  3. Soda-lime float glass
  4. Borosilicate glass

Explanation

Polycarbonate is a transparent thermoplastic with very high impact resistance and low density, used in security and sports glazing. It is softer than glass and scratches more easily, so it is specified where impact performance outweighs abrasion resistance.

Question 46Glass and Glazing Materials

In an insulating glass unit, what is the main purpose of the desiccant in the spacer?

  1. To damp vibration between panes
  2. To absorb moisture from the air space Correct answer.
  3. To bond the two lites together
  4. To reflect solar radiation

Explanation

The desiccant, typically a molecular sieve or silica gel, dries the sealed air space so that moisture does not condense on the glass surfaces inside the unit. It also helps keep the cavity clear of water vapor that would fog the unit over time.

Question 47Glass and Glazing Materials

What is the purpose of a setting block in a glazed opening?

  1. To provide a thermal break in the frame
  2. To support the bottom edge of the glass and keep it off the frame Correct answer.
  3. To seal the perimeter joint against water
  4. To hold the glass against wind load

Explanation

Setting blocks are placed under the lower edge of the glass to carry its dead load and prevent direct contact with the frame, which could cause stress concentrations and breakage. They are positioned so the glass bears on the blocks rather than on the frame sill.

Question 48Glass and Glazing Materials

Which term describes the rubber or elastomer strip compressed against the glass to weatherseal a glazed opening?

  1. Setting block
  2. Gasket Correct answer.
  3. Glazing bead
  4. Backer rod

Explanation

A gasket is a resilient strip, often EPDM or silicone, that is compressed between the glass and frame to seal the joint against air and water. Glazing beads retain the glass, setting blocks carry its weight, and backer rod is a round foam filler used behind sealant joints.

Question 49Glass and Glazing Materials

A specification calls for heat-soaked tempered glass. What is the purpose of the heat-soak process?

  1. To improve the optical clarity of the pane
  2. To increase the surface compression beyond standard tempering
  3. To allow the glass to be cut after tempering
  4. To reduce the risk of spontaneous breakage from nickel sulfide inclusions Correct answer.

Explanation

Heat soaking holds tempered glass at an elevated temperature so that nickel sulfide inclusions, which can expand and cause spontaneous fracture, transform and break the pane during the test rather than in service. It does not change the temper level or allow cutting after tempering.

Question 50Glass and Glazing Materials

A designer wants a glazing unit that limits solar heat gain while still admitting daylight. Which performance value should be compared between products?

  1. Solar heat gain coefficient Correct answer.
  2. Sound transmission class
  3. Coefficient of thermal expansion
  4. Visible light transmittance only

Explanation

The solar heat gain coefficient (SHGC) expresses the fraction of incident solar energy admitted through the glazing as heat, so a lower SHGC means less solar heat gain. Visible light transmittance describes daylight admission, and the two are balanced together when selecting solar-control glass.