CFI Surface Preparation & Safety Procedures 3 — Questions and Answers
Question 1: When patching a low spot in a concrete subfloor with a cementitious patch, what is the minimum cure time typically required before installing resilient flooring?
- 15 minutes
- 24 hours
- Follow manufacturer's instructions (typically 1–4 hours) (Correct answer)
- 72 hours minimum always
Correct answer: Follow manufacturer's instructions (typically 1–4 hours)
Cure times vary by product; always follow the specific manufacturer's data sheet, which typically ranges from 1–4 hours.
Question 2: Which condition in a wood subfloor requires correction before installing hardwood flooring?
- Subfloor moisture content of 8%
- Subfloor deflection exceeding L/360 of the span (Correct answer)
- Fastener heads slightly below the surface
- Subfloor joints staggered at 16-inch intervals
Correct answer: Subfloor deflection exceeding L/360 of the span
Deflection greater than L/360 causes the floor to flex, leading to squeaking, cracking, and adhesive failure.
Question 3: When handling and cutting fiber-cement backer board, which safety measure is most important?
- Wear heat-resistant gloves
- Use a respirator due to silica content in dust (Correct answer)
- Secure the board with a vacuum clamp
- Score and snap — never use power tools
Correct answer: Use a respirator due to silica content in dust
Fiber-cement board contains silica, and cutting generates hazardous dust requiring respiratory protection.
Question 4: A subfloor panel has an OSB stamp reading '24/16 — 7/16'. What does '24/16' indicate?
- Panel thickness in millimeters
- Maximum roof span / maximum floor span in inches (Correct answer)
- Panel weight per square foot
- Fastener spacing requirements
Correct answer: Maximum roof span / maximum floor span in inches
The span rating '24/16' means the panel can span 24 inches on roofs and 16 inches on floors between supports.
Question 5: What is the purpose of acclimating hardwood flooring before installation?
- To allow adhesive to partially cure on the planks
- To equalize moisture content between the wood and job site conditions (Correct answer)
- To pre-stress the wood to prevent cupping
- To check for factory defects before starting
Correct answer: To equalize moisture content between the wood and job site conditions
Acclimation equalizes the wood's moisture content with the environment, minimizing post-installation expansion or contraction.
Question 6: On a construction site, where should flooring adhesive containers be stored to comply with fire safety requirements?
- In a heated room above 65°F
- In a flammable materials storage cabinet away from ignition sources (Correct answer)
- Adjacent to the work area for convenience
- In the same room as propane equipment
Correct answer: In a flammable materials storage cabinet away from ignition sources
Solvent-based adhesives are flammable and must be stored in approved flammable storage cabinets away from heat and ignition.
Question 7: Which of the following is a sign of hydrostatic pressure affecting a below-grade concrete slab?
- Surface cracking in a spider web pattern
- White crystalline deposits (efflorescence) on the surface (Correct answer)
- Slab color variations from aggregate
- Shallow surface honeycombing
Correct answer: White crystalline deposits (efflorescence) on the surface
Efflorescence is caused by water moving through concrete and depositing salts, indicating active moisture migration from below.
CFI Surface Preparation & Safety Procedures 3
When patching a low spot in a concrete subfloor with a cementitious patch, what is the minimum cure time typically required before installing resilient flooring?