CFI Adhesive & Underlayment Selection 3 — Questions and Answers
Question 1: What trowel notch size is typically recommended when applying urethane adhesive for engineered hardwood flooring?
- 1/16" V-notch
- 3/32" x 3/32" square notch
- 1/4" x 3/16" V-notch (Correct answer)
- 1/2" x 1/2" square notch
Correct answer: 1/4" x 3/16" V-notch
A 1/4" x 3/16" V-notch trowel is the common manufacturer specification for urethane adhesive for engineered hardwood, providing the correct spread rate and coverage.
Question 2: When is a moisture barrier underlayment required under a floating laminate floor installed over concrete?
- Only when the concrete was poured within the last year
- Whenever the concrete subfloor is at or below grade (Correct answer)
- Only in coastal climates
- Never; laminate flooring resists moisture without a barrier
Correct answer: Whenever the concrete subfloor is at or below grade
A moisture barrier is required whenever laminate is installed over concrete at or below grade because ground moisture vapor can penetrate the slab and damage moisture-sensitive laminate cores.
Question 3: Which adhesive is best suited for bonding rubber sheet flooring in a commercial kitchen?
- Pressure-sensitive acrylic adhesive
- Epoxy adhesive rated for grease and chemical resistance (Correct answer)
- Water-based contact cement
- Standard floor leveling compound
Correct answer: Epoxy adhesive rated for grease and chemical resistance
Epoxy adhesive rated for grease and chemical resistance is required in commercial kitchens where constant exposure to cooking oils, cleaners, and heavy traffic would degrade less resistant adhesives.
Question 4: What is 'flash time' in the context of contact cement adhesives?
- The time required for the cement to fully cure after bonding
- The time allowed for the solvent to evaporate before mating the two surfaces (Correct answer)
- The maximum working time after mixing two components
- The time the installer has before the cement skins over on the trowel
Correct answer: The time allowed for the solvent to evaporate before mating the two surfaces
Flash time is the period required after applying contact cement to both surfaces during which the solvent evaporates, making the adhesive ready for the bond to occur on contact.
Question 5: A substrate has a moisture vapor emission rate (MVER) of 8 lbs per 1,000 sq ft per 24 hours. What action must the installer take before installing flooring with standard adhesive?
- Proceed normally; 8 lbs is within acceptable range for all adhesives
- Apply a moisture-mitigation coating or use an adhesive rated for high MVER (Correct answer)
- Install a floating floor system and skip adhesive entirely
- Sand the concrete surface to improve adhesion
Correct answer: Apply a moisture-mitigation coating or use an adhesive rated for high MVER
An MVER of 8 lbs exceeds the 3–5 lb threshold acceptable for most standard adhesives, requiring either a moisture-mitigation coating or a specifically rated adhesive system.
Question 6: When installing carpet over a concrete slab, which type of underlayment provides the best combination of cushioning and moisture protection?
- Bonded polyurethane foam without a film barrier
- Prime polyurethane foam without backing
- Rebond foam with an attached moisture-barrier film (Correct answer)
- Felt pad only
Correct answer: Rebond foam with an attached moisture-barrier film
Rebond foam with an attached moisture-barrier film provides cushioning for comfort and protects the carpet and foam from concrete moisture vapor transmission.
Question 7: Which factor most directly affects adhesive spread rate and coverage per gallon?
- Ambient temperature at time of installation
- Trowel notch size and shape (Correct answer)
- Brand of adhesive manufacturer
- Color of the adhesive
Correct answer: Trowel notch size and shape
Trowel notch size and shape directly control how much adhesive is deposited per square foot, determining coverage rate and ensuring the correct adhesive film thickness.
CFI Adhesive & Underlayment Selection 3
What trowel notch size is typically recommended when applying urethane adhesive for engineered hardwood flooring?