Free Lather (Interior Systems Mechanic) – Red Seal Examination Practice Questions

Sample Practice Questions

Try these 10 sample questions from the Lather (Interior Systems Mechanic) – Red Seal Examination practice bank. Each includes the answer and explanation. Continue with the interactive practice above to review the full question set.

1. 1A lather checks the WHMIS classification of a chemical before using it on site. Which pictogram corresponds to Skin corrosion, Category 1?

   1. A.Exclamation mark
   2. B.Flame
   3. C.Gas cylinder
   4. D.CorrosionCorrect answer: D

   Explanation: The Canadian Centre for Occupational Health and Safety lists the corrosion pictogram for "Skin corrosion/irritation – Skin corrosion (Category 1, 1A, 1B and 1C)". The product's stated category therefore calls for the corrosion pictogram.

   Reference: WHMIS - Pictograms — What pictograms are used with WHMIS hazard classes and categories? Corrosion

2. 2A lather checks the specified metal thickness of non-loadbearing steel studs on an Ontario project governed by Division B, Section 9.24 of the 2024 Building Code. Which thickness must the lather compare with the code minimum?

   1. A.The overall steel thickness with coatings
   2. B.The overall thickness of nested sections
   3. C.The base steel thickness plus one coating
   4. D.The base steel thickness without coatingsCorrect answer: D

   Explanation: The code states, "Metal thickness specified in this Section shall be the minimum base steel thickness exclusive of coatings." The coating cannot be counted toward the prescribed steel thickness.

   Reference: 2024 Ontario Building Code Compendium — Division B, Part 9 — 9.24.1.3, Metal Thickness

3. 3An Ontario wall has a single layer of gypsum board screwed to wood studs at 600 mm centres. The board is not providing required bracing, lateral stud support or fire protection. Under Article 9.29.5.9 of the 2024 Building Code, what maximum screw spacing applies along the vertical supports?

   1. A.200 mm o.c.
   2. B.300 mm o.c.Correct answer: B
   3. C.150 mm o.c.
   4. D.600 mm o.c.

   Explanation: The source states, "not more than 300 mm o.c. on vertical wall supports where the supports are more than 400 mm o.c., or" The supports are more than 400 mm apart, so the relevant maximum screw spacing is 300 mm.

   Reference: 2024 Ontario Building Code Compendium — Division B, Part 9 — 9.29.5.9(3)(a)

4. 4An Ontario wall assembly uses a sheet material as its principal resistance to air leakage. Under Article 9.25.3.2 of the 2024 Building Code, what is the maximum permitted material air leakage at 75 Pa?

   1. A.0.02 L/(s·m²)Correct answer: A
   2. B.0.10 L/(s·m²)
   3. C.0.05 L/(s·m²)
   4. D.0.20 L/(s·m²)

   Explanation: The source states, "air leakage characteristic not greater than 0.02 L/(s · m 2 ) measured at an air pressure differential of 75 Pa." The material property is limited to 0.02 L/(s·m²) at the specified test pressure; it is not a whole-building leakage allowance.

   Reference: 2024 Ontario Building Code Compendium — Division B, Part 9 — 9.25.3.2(1), Air Barrier System Properties

5. 5Before storing a newly delivered sealant, a lather checks its WHMIS safety data sheet for safe storage conditions and incompatible materials. Which section should the lather consult?

   1. A.Section 5
   2. B.Section 7Correct answer: B
   3. C.Section 4
   4. D.Section 6

   Explanation: CCOHS advises workers to "understand safe handling and storage instructions (Section 7)". The lather should therefore consult Section 7 for the product's storage conditions.

   Reference: WHMIS - Safety Data Sheet (SDS) — As a worker, when would I use an SDS?

6. 6A delivery of 0.85 mm studs is specified for an Ontario non-loadbearing wall governed by Article 9.24.2.3 of the 2024 Building Code. What minimum steel thickness must the matching runners have?

   1. A.0.46 mm
   2. B.0.54 mm
   3. C.0.85 mmCorrect answer: C
   4. D.1.20 mm

   Explanation: The code states, "Runners for interior and exterior non-loadbearing walls shall have a thickness not less than the thickness of the corresponding studs and shall have not less than 30 mm flanges." The runner must be at least as thick as the 0.85 mm stud; the question asks the minimum, not a thicker acceptable substitution.

   Reference: 2024 Ontario Building Code Compendium — Division B, Part 9 — 9.24.2.3, Runners

7. 7During a board-edge fastening check on an Ontario project, the lather measures screws in single-layer gypsum board attached to wood framing. What minimum edge distance is required by Sentence 9.29.5.9(6) of the 2024 Building Code?

   1. A.6 mm
   2. B.10 mmCorrect answer: B
   3. C.15 mm
   4. D.20 mm

   Explanation: The source states, "Screws shall be located not less than 10 mm from the edge of the board." The requested edge-distance minimum is 10 mm; larger values do not define that minimum.

   Reference: 2024 Ontario Building Code Compendium — Division B, Part 9 — 9.29.5.9(6)

8. 8A lather checks a conventional vapour-barrier material for an Ontario insulated wall that does not use the foundation-wall variable-permeance exception. Under Article 9.25.4.2 of the 2024 Building Code, what maximum dry-cup permeance applies?

   1. A.300 ng/(Pa·s·m²)
   2. B.150 ng/(Pa·s·m²)
   3. C.30 ng/(Pa·s·m²)
   4. D.60 ng/(Pa·s·m²)Correct answer: D

   Explanation: The source states, "vapour barriers shall have a permeance not greater than 60 ng/(Pa×s×m2)" The ordinary dry-cup maximum is 60 ng/(Pa·s·m²). The different wet-cup condition for variable-permeance foundation barriers is excluded.

   Reference: 2024 Ontario Building Code Compendium — Division B, Part 9 — 9.25.4.2(1), Vapour Barrier Materials

9. 9A lather needs hand snips with crescent-shaped jaws to cut a tight circular opening in sheet metal. Which snips fit that description?

   1. A.Universal snips
   2. B.Hawk's bill snipsCorrect answer: B
   3. C.Straight snips
   4. D.Offset snips

   Explanation: CCOHS states that "Hawk's bill snips (with crescent-shaped jaws) are used for cutting tight circles." The described jaws and cut match hawk's bill snips.

   Reference: Hand Tools - Snips — What are some safety tips to know when using snips?

10. 10On an Ontario interior non-loadbearing wall governed by Section 9.24 of the 2024 Building Code, a lather has fixed the runner near each end. What is the maximum permitted spacing of its intermediate attachments to the building?

    1. A.300 mm o.c.
    2. B.600 mm o.c.Correct answer: B
    3. C.800 mm o.c.
    4. D.400 mm o.c.

    Explanation: The code states, "Runners required in Sentence (1) shall be securely attached to the building at approximately 50 mm from the ends, and at intervals of not more than 600 mm o.c. for interior walls and 300 mm o.c. for exterior walls." The specified interior-wall condition selects the 600 mm maximum, rather than the exterior-wall value.

    Reference: 2024 Ontario Building Code Compendium — Division B, Part 9 — 9.24.3.1(2), Installation of Runners