Cavityboard™ is a semi-rigid mineral wool insulation board built for ventilated rainscreen and exterior cavity wall assemblies.
Strengthen your building envelope with PowerWool™ Cavityboard™, a semi-rigid mineral wool insulation board engineered for airflow-friendly cavity wall performance, fire safety, and long-term thermal stability.
Designed for ventilated rainscreen and exterior cavity wall assemblies, Cavityboard™ delivers continuous insulation behind a wide range of cladding types while supporting drainage, moisture management, and energy efficiency. At a lightweight 4.5 lbs/ft³ and available in thicknesses from 1.5″ to 8″, it fits cleanly into cavity depths across residential and light-commercial designs.
PowerWool™ Cavityboard™ helps create safer, quieter, and more resilient buildings by resisting fire, repelling moisture, and maintaining stable R-4.2-per-inch thermal performance over time. It’s approved for use in Canada and the U.S., and suitable for substitution in rated NFPA 285 and ASTM E119 wall assemblies.
| CHARACTERISTIC | RESULT | TEST STANDARD | ||||||||||||||||||||||||||||||||||||||||||||||||||||||
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| Compliance | Mineral Fiber Block and Board Thermal Insulation – Compliant Mineral Fiber Thermal Insulation for Buildings – Compliant |
ASTM C612 CAN/ULC S702.1 |
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| Reaction to Fire | Flame spread index = 0; Smoke developed index = 0 Flame spread index = 0; Smoke developed index = 0 Determination of Non Combustibility of Building Materials – Non Combustible Behaviour of materials at 750°C – Non Combustible |
ASTM E84 (UL 723) CAN/ULC S102 CAN/ULC S114 ASTM E136 |
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| Density | 4.5 lbs/ft³ (72kg/m³) – Actual 6 lbs/ft³ (96 kg/m³) – Nominal |
ASTM C303 | ||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Dimensional Stability | Linear Shrinkage = Pass @1200°F (650°C) | ASTM C356 | ||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Corrosion Resistance | Corrosion of Steel – Passed | ASTM C665 | ||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Thermal Resistance | R-Value / inch @ 75°F — 4.2 hr.ft².F/Btu RSI value / 25.4 mm @ 24°C — 0.74 m²K/W |
ASTM C518 | ||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Reaction to Moisture | Moisture Sorption – Pass Water Vapor Transmission, Desiccant Method – 1670ng/Pa.s.m² (29 perm) Determination of Fungi Resistance – Passed |
ASTM C1104 ASTM E96 ASTM C1338 |
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| Dimensions | 1½” (38 mm) to 6″ (152.4 mm) in ½” increments 16″ × 48″ (406 mm × 1219 mm) 24″ × 48″ (610 mm × 1219 mm) |
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| Acoustic Performance |
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ASTM C423-23 ASTM E795-23 |
PowerWool™ CavityBoard™ is engineered for versatility in commercial, industrial, and multi-story residential construction, including:
From cavity wall assemblies to ventilated facades, PowerWool™ CavityBoard™ delivers a durable, fire-safe, and moisture-resilient solution that simplifies installation while maintaining long-term thermal and acoustic performance.
Sizes Available: All boards available in 24″x48″ and 16″ x 48″ – in sizes ranging in thickness from 1″ to 8″ thick.
Non-combustible mineral wool insulation, rated zero flame spread and zero smoke developed, for maximum safety in demanding environments.
