Subfloor Assessment & Preparation Flashcards
7 cards from real CFI practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 7 Subfloor Assessment & Preparation flashcards as text
Subfloor panels should be installed with a gap between panel edges. What is the recommended gap size?
Answer: 1/8 inch
A 1/8-inch gap between panel edges allows for seasonal expansion and prevents panel buckling.
Which subfloor defect is MOST likely to cause ridging or telegraphing through sheet vinyl flooring?
Answer: Exposed panel edges or fastener heads that are proud
Proud fasteners or panel edges create hard points that telegraph directly through thin resilient sheet goods.
What is the correct fastener pattern when installing a second layer of plywood underlayment over an existing subfloor?
Answer: Fasten at 6 inches on center in the field and 4 inches at edges
Closer edge fastening (4") prevents edge movement and peaking, while 6" field fastening provides adequate substrate stiffness.
Before installing flooring over a radiant heat subfloor system, what is the maximum substrate surface temperature allowed during installation?
Answer: 85°F
Most manufacturers require the radiant heat system be operating and surface temperature not exceed 85°F during installation to prevent adhesive or material issues.
A concrete slab has an alkalinity (pH) reading of 11. What is the significance for flooring installation?
Answer: High pH can break down adhesive bonds and require primer or mitigation
Concrete pH above 9 can chemically attack certain adhesives, making pH testing and appropriate primer selection critical.
When grinding down a high spot on a concrete slab, what safety equipment is mandatory?
Answer: Respirator, eye protection, and hearing protection
Concrete grinding generates silica-laden dust, requiring respiratory protection (N95 minimum), plus eye and hearing protection.
What does an L/360 deflection rating mean for a subfloor system?
Answer: The span length divided by 360 equals the maximum allowable deflection
L/360 means the maximum allowable mid-span deflection is the joist span length divided by 360, a common benchmark for tile installations.