EIFS Installation Techniques & Best Practices 2 — Questions and Answers
Question 1: When installing EIFS over a wood-framed wall, what is the minimum required drainage gap behind the insulation board?
- 1/16 inch
- 1/8 inch
- 1/4 inch (Correct answer)
- 3/8 inch
Correct answer: 1/4 inch
A minimum 1/4-inch drainage gap is required behind the insulation board in drainage-type EIFS assemblies over wood framing to allow moisture to escape.
Question 2: Which type of mesh is required at re-entrant corners in an EIFS installation to prevent cracking?
- Standard fiberglass mesh only
- Diagonal corner mesh or stress-relief strips (Correct answer)
- Metal corner bead without mesh
- Heavy-duty woven mesh only
Correct answer: Diagonal corner mesh or stress-relief strips
Diagonal corner mesh or stress-relief strips are installed at re-entrant corners because stress concentrations at these points require additional reinforcement beyond standard mesh.
Question 3: What is the correct sequence for applying base coat and mesh in a standard EIFS wall assembly?
- Apply mesh first, then embed with base coat
- Apply base coat, embed mesh, then apply additional base coat over mesh (Correct answer)
- Apply base coat, let dry, then apply mesh with adhesive
- Apply mesh with adhesive, then cover with finish coat only
Correct answer: Apply base coat, embed mesh, then apply additional base coat over mesh
The correct sequence is to apply a base coat, embed the mesh into the wet base coat, then apply a second pass of base coat to fully encapsulate the mesh.
Question 4: What is the minimum distance EIFS should terminate above finished grade?
- 2 inches
- 4 inches
- 6 inches (Correct answer)
- 8 inches
Correct answer: 6 inches
EIFS must terminate a minimum of 6 inches above finished grade to prevent soil contact, moisture wicking, and insect intrusion.
Question 5: During EIFS installation, why must expansion joints be installed at floor lines in multi-story construction?
- To allow for thermal expansion of the finish coat only
- To accommodate differential movement between framing levels and prevent cracking (Correct answer)
- To provide a decorative accent at floor transitions
- To comply with energy code requirements for thermal breaks
Correct answer: To accommodate differential movement between framing levels and prevent cracking
Expansion joints at floor lines accommodate differential movement between framing levels caused by thermal cycling, moisture changes, and structural deflection.
Question 6: What is the maximum allowable time between application of adhesive and placement of insulation boards in most EIFS systems?
- 5 minutes
- 15 minutes (Correct answer)
- 30 minutes
- 60 minutes
Correct answer: 15 minutes
Most EIFS adhesives must have insulation boards placed within approximately 15 minutes to ensure adequate bond before the adhesive skins over.
Question 7: When two insulation boards meet at an outside corner, how should they be installed?
- Butted together flush at the corner with mesh lapped over
- Lapped and interlocked alternately at each course (woven corners) (Correct answer)
- Mitered at 45 degrees and joined with adhesive
- Each board stopped short of the corner with a metal bead bridging the gap
Correct answer: Lapped and interlocked alternately at each course (woven corners)
Outside corners require insulation boards to be lapped and interlocked alternately at each course (woven corners) to eliminate continuous vertical joints that could crack.
EIFS Installation Techniques & Best Practices 2
When installing EIFS over a wood-framed wall, what is the minimum required drainage gap behind the insulation board?