CFI Adhesive & Underlayment Selection 5 — Questions and Answers
Question 1: Which standard governs moisture testing of concrete substrates before flooring installation in the US?
- ASTM F710
- ASTM F1869 (Correct answer)
- ANSI A108.02
- NFPA 13
Correct answer: ASTM F1869
ASTM F1869 is the standard test method for measuring moisture vapor emission rate (MVER) from concrete using anhydrous calcium chloride, widely used before flooring installation.
Question 2: When must a secondary moisture barrier be installed under underlayment in a crawl space application?
- Only when mold is already visible
- Always, as part of proper crawl space moisture management regardless of conditions (Correct answer)
- Only when installing ceramic tile
- Only when the soil is visibly wet
Correct answer: Always, as part of proper crawl space moisture management regardless of conditions
A ground cover moisture barrier should always be installed in crawl spaces as standard practice because soil continuously releases moisture vapor that can migrate upward into floor systems.
Question 3: An installer is bonding sheet vinyl to a wood subfloor using a full-spread adhesive. What is the correct method to ensure proper bond?
- Roll the vinyl immediately after positioning it
- Use a 100-lb floor roller to ensure full contact after positioning (Correct answer)
- Walk the vinyl into the adhesive with foot pressure only
- Lay the vinyl and allow adhesive to cure without any rolling
Correct answer: Use a 100-lb floor roller to ensure full contact after positioning
A 100-lb floor roller ensures full contact between the vinyl and adhesive, eliminating air pockets and achieving consistent bond across the entire surface.
Question 4: Which underlayment product is most appropriate to use between an old ceramic tile subfloor and a new porcelain tile installation?
- Standard foam underlayment
- Uncoupling membrane (Correct answer)
- Rosin paper
- 6-mil polyethylene sheeting
Correct answer: Uncoupling membrane
An uncoupling membrane allows the new tile layer to move independently from the old substrate, preventing crack transmission from the old grout joints or any minor substrate movement.
Question 5: What is the primary reason to back-roll adhesive after troweling when installing resilient flooring?
- To cool the adhesive for longer open time
- To flatten trowel ridges and achieve a more uniform adhesive film thickness (Correct answer)
- To activate the adhesive's bonding agents
- To remove excess adhesive before laying the floor
Correct answer: To flatten trowel ridges and achieve a more uniform adhesive film thickness
Back-rolling with a short-nap roller collapses trowel ridges to create a uniform film, preventing ridge telegraphing through thin resilient flooring materials.
Question 6: A flooring contractor selects an underlayment with an STC rating of 52. What does this rating measure?
- The underlayment's resistance to compression under static loads
- The underlayment's ability to reduce airborne sound transmission between rooms (Correct answer)
- The underlayment's impact resistance rating
- The underlayment's moisture vapor transmission rate
Correct answer: The underlayment's ability to reduce airborne sound transmission between rooms
STC (Sound Transmission Class) measures how well a building component reduces airborne sound transmission, such as voices or music, between adjacent spaces.
Question 7: When installing adhesive-backed LVT over an existing VAT (vinyl asbestos tile) floor, what is the recommended approach?
- Sand the VAT surface for better adhesion before installation
- Encapsulate the VAT with an approved embossing leveler and install over it without disturbing tiles (Correct answer)
- Remove all VAT and adhesive completely before any new installation
- Apply a moisture barrier directly over the VAT surface
Correct answer: Encapsulate the VAT with an approved embossing leveler and install over it without disturbing tiles
Intact VAT should be encapsulated with an embossing leveler rather than disturbed because sanding or removing VAT releases asbestos fibers, posing a serious health hazard.
CFI Adhesive & Underlayment Selection 5
Which standard governs moisture testing of concrete substrates before flooring installation in the US?