Integrating Rigid Exterior Insulation with Rock Wool

Benefits of Exterior Insulation

• Thermal Comfort: Enhances internal thermal comfort.
• Energy Efficiency: Increases energy efficiency of the building.
• Durability: Prevents condensation, reducing mold and rot issues. Keeps framing closer to interior conditions.

Wall Assembly Overview

• Insulation Layers: Two layers of rigid rock wool (Comfortboard).
• Thermal Break: Creates a complete thermal break between the framing and the exterior.
• Stable Temperature: Prevents condensation on the sheathing.
• Weather Resistive Barrier: Installed under the insulation. Self-adhered barrier offers robust water and air control by bonding to exterior sheathing.

Alternatives and Considerations

• Alternative Materials: EPS foam or polyisocyanurate can be used but requires a drainage gap.
• Rock Wool Advantage: Drains easily due to textured surface.
• Drainage for Foam: Use a drainage mesh or textured/grooved insulation to prevent water buildup.
• Gap Size: Ideal drainage gap is between 1/16th to 1/8th inch. Larger gaps reduce thermal resistance.

Fastening System

• Insulation Fastening: Use insulation screws/nails with polypropylene washers to reduce compression.
• Furring Strips: Vertical 1x4 furring strips secured to the studs provide a base for exterior cladding.
• Loading Transfer: Furring strips transfer loads to the structure.
• Cladding Orientation: Both horizontal and vertical cladding options require different setup.

Additional Considerations

• Sheathing Options: CDX plywood, OSB, or gypsum sheathing for increased fire resistance.
• Interior Insulation: Fill stud cavities with rock wool R23 comfort bat (approx. R39 total wall value).
• Effective R-Value: Inclusion of thermal bridges (wood studs) reduces effective R-value to R2.5 at those points.
• Fire Protection: Rock wool provides additional fire protection.

Base Wall Details

• Flashing: Fluid-applied or compatible flashing tape at stem wall to frame connection.
• Metal Base Flashing: Includes drip edge to direct water away.
• Bug Screen: Mesh material to prevent bugs while allowing drainage.
• Joint Orientation: Staggered and offset joints for better insulation.

Climate Considerations

• Variable Requirements: Insulation needs depend on climate zone.
• Condensation Prevention: More critical in colder climates to prevent condensation.
• Vapor Retarders: Alternative to rigid insulation in managing vapor movement.

Final Notes

• Wall Assembly Details: Available at aeri-designs.com.
• Further Resources: CAD details for various high-performance wall assemblies.

Links to resources are available in the video description.