EIFS Substrate Preparation & Surface Compatibility 1 — Questions and Answers
Question 1: What is the maximum allowable moisture content of a wood sheathing substrate before EIFS application, according to industry standards?
- 10%
- 19% (Correct answer)
- 25%
- 30%
Correct answer: 19%
Wood sheathing must have a moisture content of 19% or less before EIFS installation to prevent adhesion failure and moisture-related damage.
Question 2: Which of the following substrate defects MUST be corrected before applying EIFS adhesive?
- Minor surface discoloration
- Efflorescence on concrete masonry (Correct answer)
- Hairline cracks less than 1/16 inch
- Slight texture variation
Correct answer: Efflorescence on concrete masonry
Efflorescence indicates ongoing moisture migration and must be removed and the source corrected before EIFS application to ensure proper adhesion.
Question 3: When inspecting a concrete masonry unit (CMU) substrate for EIFS compatibility, what is the primary concern regarding form release agents?
- They improve adhesion to the substrate
- They can prevent proper bonding of EIFS adhesive (Correct answer)
- They reduce the wall's R-value
- They are required for smooth surface preparation
Correct answer: They can prevent proper bonding of EIFS adhesive
Form release agents leave a chemical residue on concrete surfaces that inhibits adhesion of EIFS components and must be removed before application.
Question 4: What is the minimum compressive strength of concrete required as an acceptable EIFS substrate?
- 1,000 psi
- 2,000 psi (Correct answer)
- 3,000 psi
- 5,000 psi
Correct answer: 2,000 psi
A minimum compressive strength of 2,000 psi is generally required for concrete to provide adequate structural support for EIFS without pullout failure.
Question 5: Which type of sheathing is INCOMPATIBLE with certain EIFS adhesives due to its glass mat facing?
- Exterior gypsum sheathing (DensGlass) (Correct answer)
- OSB (Oriented Strand Board)
- Plywood
- Exterior fiber cement board
Correct answer: Exterior gypsum sheathing (DensGlass)
Some EIFS adhesives are not compatible with glass mat-faced gypsum sheathing and require a specific compatible adhesive or primer per the manufacturer's specifications.
Question 6: Before applying EIFS to a previously painted concrete surface, an inspector should verify that the existing paint is:
- At least 10 years old
- Well-bonded and not peeling (Correct answer)
- Oil-based rather than latex
- Applied in multiple coats
Correct answer: Well-bonded and not peeling
Existing paint must be well-bonded to the substrate; peeling or delaminating paint will cause EIFS failure since it cannot bond through a weak intermediate layer.
Question 7: What test is commonly used in the field to assess the bond strength of an existing coating or substrate before EIFS installation?
- Schmidt hammer test
- Pull-off adhesion test (Correct answer)
- Moisture probe test
- Core compressive test
Correct answer: Pull-off adhesion test
A pull-off adhesion test measures the tensile bond strength of an existing surface coating or substrate to determine if it can support EIFS installation.
EIFS Substrate Preparation & Surface Compatibility 1
What is the maximum allowable moisture content of a wood sheathing substrate before EIFS application, according to industry standards?