CFI Subfloor Assessment & Preparation 4 — Questions and Answers
Question 1: Which condition in an existing vinyl composition tile (VCT) floor may indicate the presence of asbestos?
- Tiles installed after 1990
- Tiles that are 9×9 inches and installed before 1980 (Correct answer)
- Tiles with a textured surface finish
- Tiles with visible moisture damage
Correct answer: Tiles that are 9×9 inches and installed before 1980
9×9-inch VCT tiles and their adhesive installed before 1980 commonly contained asbestos and must be tested before disturbance.
Question 2: What is the recommended acclimation period and environment for hardwood flooring before installation?
- 24 hours at any temperature
- 3–5 days at 60–80°F with 30–50% RH matching occupied conditions (Correct answer)
- 7 days in the delivery packaging
- No acclimation is needed for engineered hardwood
Correct answer: 3–5 days at 60–80°F with 30–50% RH matching occupied conditions
Hardwood must acclimate at living conditions (60–80°F, 30–50% RH) for 3–5 days so it reaches equilibrium moisture content before installation.
Question 3: When is it necessary to install a vapor retarder under a wood subfloor over a crawl space?
- Only in coastal climates
- Whenever the crawl space is unconditioned or has exposed soil (Correct answer)
- Only when the joist spacing exceeds 16 inches OC
- Only if the homeowner requests it
Correct answer: Whenever the crawl space is unconditioned or has exposed soil
Exposed soil in an unconditioned crawl space is a major moisture source; a polyethylene vapor retarder is required to protect the wood subfloor above.
Question 4: A plywood subfloor panel has face checking (surface cracks). What is the appropriate action before installing hardwood over it?
- Sand the checks smooth and proceed
- Fill the checks with floor patching compound and allow to cure (Correct answer)
- Replace the panel
- Install a 1/4-inch lauan underlayment over it
Correct answer: Fill the checks with floor patching compound and allow to cure
Surface checks must be filled and flattened so they don't telegraph through or create weak points in the finished floor.
Question 5: What is the primary reason for staggering end joints of subfloor panels by at least 4 feet?
- To reduce the number of panels needed
- To prevent a continuous joint line that creates a weak point or ridge (Correct answer)
- To make cutting easier on site
- To comply with fire code requirements
Correct answer: To prevent a continuous joint line that creates a weak point or ridge
Staggering end joints distributes stress and prevents a continuous weak line that could crack finishes or create a noticeable ridge.
Question 6: Which type of concrete slab condition would require mechanical scarification rather than chemical etching before adhesive application?
- A slab with hairline cracks
- A slab with an existing sealer or curing compound on the surface (Correct answer)
- A slab with high alkalinity readings
- A slab with minor surface dusting
Correct answer: A slab with an existing sealer or curing compound on the surface
Surface sealers and curing compounds create a bond-breaking film that chemical etching cannot fully remove, requiring scarification to achieve a clean, porous surface.
Question 7: Subfloor squeaks in a wood-framed floor are MOST commonly caused by what condition?
- Panels with too high a moisture content at installation
- Movement between the subfloor panel and the joist due to inadequate fastening or gaps (Correct answer)
- Using OSB instead of plywood
- Joists that are over-spanned
Correct answer: Movement between the subfloor panel and the joist due to inadequate fastening or gaps
Squeaks result from panels rubbing against joist tops or fasteners loosening over time, causing friction noise with foot traffic.
CFI Subfloor Assessment & Preparation 4
Which condition in an existing vinyl composition tile (VCT) floor may indicate the presence of asbestos?