Everything You Need to Know About Base Coat for EIFS Systems
The base coat is one of the most important components of an EIFS (Exterior Insulation and Finish System). It forms the bond between the insulation board and the finish layer, while holding fiberglass mesh in place to add strength and crack resistance. A properly applied base coat creates a smooth, reinforced surface ready for the finishing touches.
What Is EIFS Base Coat?
Base coats are typically either cementitious or acrylic-based materials that are applied over the insulation layer. They act as a bonding and leveling layer, embedding fiberglass mesh to provide structural strength and resistance to cracking, impacts, and environmental wear.
- Cementitious base coats contain Portland cement and are known for their high durability and moisture resistance.
• Acrylic base coats are premixed and more flexible, often used in areas with frequent temperature changes to reduce cracking.
How to Apply EIFS Base Coat
Proper application is key to ensuring your base coat performs as intended. Here’s a general step-by-step process:
- Ensure the insulation board is clean, dry, and securely fastened to the substrate.
- Using a stainless steel trowel, apply the base coat to the insulation board at a uniform thickness of about 1/8 inch.
- While the base coat is still wet, embed fiberglass mesh into the surface, smoothing it out to eliminate wrinkles or air pockets.
- Apply additional base coat over the mesh as needed to fully embed it and create a flat surface.
- Allow the base coat to cure completely—usually 24 to 48 hours—before applying the finish coat.
Best Practices & Common Mistakes
- Always follow manufacturer instructions regarding mix ratios and drying times.
- Avoid applying base coat in extreme temperatures (below 40°F or above 100°F).
- Do not allow the base coat to dry before embedding the mesh—it must remain wet for proper adhesion.
- Ensure even coverage and full mesh embedment to avoid weak spots or surface failures.
Why Base Coat Quality Matters
The base coat serves as the structural middle layer of your EIFS assembly. If it’s too thin, improperly cured, or contains poor materials, you risk delamination, cracking, and reduced impact resistance. A high-quality base coat not only improves performance but also makes application easier and more consistent.
Choose Rescom for Reliable EIFS Base Coat Products
At Rescom Products, we offer EIFS base coats designed for superior bonding strength, ease of use, and long-term durability. Our products pair perfectly with our fiberglass mesh and other EIFS accessories, helping you build systems that last. Contact us today to learn more or get expert guidance on your next project.
