Exterior Insulation and Finish Systems (EIFS) require precise detailing to manage moisture, protect thermal layers, and maintain the integrity of the cladding system. This article outlines best practices for drainage EIFS, including backwrapping, base-of-wall terminations, and flashing integration.
EIFS Drainage Systems
- Use grooved foam insulation boards or drainage mats behind the base coat to promote vertical drainage
- Incorporate weep tracks or vented starter tracks at the base of the wall
- Backer board or WRB must be sealed and lapped to direct incidental moisture outward
- Do not seal bottom edges of EIFS—allow for open drainage path and ventilation
Backwrapping and Insulation Termination
Backwrapping protects insulation edges from delamination and UV exposure. Wrap reinforcing mesh around all termination edges and embed in base coat. Apply primer or adhesive to exposed insulation prior to coating. Use edge beads or PVC profiles for sharp termination lines where backwrapping is not feasible.
Flashing Integration and Openings
- Install head and sill flashings with drip edges and end dams at all penetrations
- Embed diagonal mesh (“butterfly” reinforcement) at corners of windows and doors
- Use compatible sealants and backer rod at all dissimilar material joints
- Control joints must align with insulation joints and be fully sealed
Quality Control and Best Practices
- Inspect drainage path for obstructions or sealed-off vents before finish coat
- Check mesh embedment and backwrap adhesion at all edges and joints
- Photograph termination points, especially base-of-wall, parapet, and sill locations
- Mockups should reflect full edge, joint, and flashing conditions and be approved before full installation
Maintain minimum 6-inch clearance from grade to EIFS base termination and never install below-grade.
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