NCCER Glazier common mistakes
NCCER Glazier · Understand the traps and how to avoid them.
Treating the safety domain as trivia and memorizing only the 'big' rules (fall protection, hard hats) while ignoring glazing-specific hazards such as glass handling, sharp-edge cuts, and suction-cup failures.
Candidates assume the safety domain is filler and skim it, so they miss questions on cut-resistant PPE, glass-carrying posture, and safe storage of lites on A-frames.
What to do instead
Build a one-page hazard map per task (carry, cut, set, seal) listing the PPE, lifting technique, and housekeeping rule for each, then self-quiz on the glazing-specific hazards, not just general construction safety.
Choosing a glass type or thickness by eyeballing the opening or copying what was on the job site instead of checking the design/specification for the required thickness, tempering, and safety-glazing location.
Field habit and 'that's what we always use' override the submittal and code tables, and candidates forget that safety glazing is location-driven (doors, sidelites, low glazing, wet areas).
What to do instead
Memorize the logic: safety glazing is determined by location and size, and thickness is set by span and design load, not appearance. Practice reading a spec section and matching each opening to its required glass callout.
Confusing tempered, heat-strengthened, and laminated glass in terms of break pattern, strength, and where each is permitted.
The terms sound similar and candidates memorize 'tempered is strong' without learning the fracture pattern (dice-like cubes), edge limitations, or that heat-strengthened is not safety glazing.
What to do instead
Make a three-column comparison (break pattern, relative strength, safety-glazing status, typical use) and drill it until you can state each from memory, including that cutouts and edge grinding are not allowed after tempering.
Mixing up the framing and storefront components-head, sill, jamb, mullion, transom, and the difference between a storefront and a curtain wall-when answering system questions.
Candidates learn the parts visually on site but never attach the correct names, so they misread questions about which member carries dead load or accommodates movement.
What to do instead
Sketch a storefront elevation and label every member and its function (head carries, sill bears and drains, mullions divide, expansion joints allow movement). Then answer practice questions using only the labels.
Ignoring setting-block placement and glazing-channel clearances, treating them as minor details rather than structural requirements.
Blocks and clearances are hidden after installation, so candidates underestimate them and miss questions on block location, load-bearing versus spacer blocks, and required edge clearance.
What to do instead
Learn the rule set: blocks at specified points to carry the lite, edge clearance to prevent contact, and weep-path continuity. Draw a section detail showing block, setting tape, and clearance, then explain each in your own words.
Handling and setting glass without the correct lifting equipment or crew technique, and answering installation questions as if a lite can be manhandled into place.
Candidates default to 'just lift it' and forget suction cups, vacuum lifter ratings, slings, and the two-person minimum for large lites, so they miss handling and equipment questions.
What to do instead
Memorize the handling hierarchy: mechanical lifter for large/heavy lites, rated suction cups inspected before use, proper carry posture, and never lifting by edges or in wind. Tie each rule to the failure it prevents.
Treating sealants as interchangeable and picking any caulk for a joint instead of matching the sealant to the joint movement, substrate, and exposure.
On site 'caulk is caulk', so candidates never learn joint design, movement capability, backer rod, and bond-breaker tape, and they miss questions on sealant selection.
What to do instead
Study sealant families by movement class and substrate compatibility, and learn the three-part joint (backer rod, bond breaker, sealant). Practice choosing a sealant for a given joint width, movement, and exposure.
Skipping weatherproofing details-weep holes, drainage paths, flashing, and gasket compression-and answering only about the visible sealant bead.
Water management is invisible in the finished wall, so candidates focus on the bead and forget that most leaks come from blocked drainage and poor lap sequencing.
What to do instead
Trace the water path from the exterior face to the weep outlet for a storefront and a curtain wall, and memorize the rule that laps shed water outward and downward. Quiz yourself on what blocks a weep path and how to prevent it.
Ignoring the sequence and curing requirements of finishing work-cleaning, sealant cure time, protective film removal, and hardware adjustment-and treating finishing as an afterthought.
Candidates study installation and stop there, so they miss questions on film removal timing, cleaner compatibility, and when sealant can be tooled or painted.
What to do instead
Build a finishing checklist in order: remove protective film within the manufacturer's window, clean with a compatible cleaner, tool sealant before skinning, allow full cure before stress, then adjust and verify hardware.
Answering code and standards questions from memory of a single job instead of the referenced standard, and guessing when the exact requirement is unknown.
Candidates rely on site practice and 'we always did it this way', so they miss questions tied to safety-glazing location rules, load tables, and manufacturer instructions.
What to do instead
When a question references a standard or manufacturer instruction, reason from the stated rule rather than habit. Flag any fact you cannot state confidently for review, and study that topic until you can explain the requirement and why it exists.