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CAVITYROCK® is a semi-rigid insulation board designed for exterior cavity wall and rainscreen applications. These products offer superior long-term thermal efficiency, fire resistance, moisture control, acoustic performance and are compatible with numerous framing systems and cladding attachment systems.

CAVITYROCK® in thicknesses of up to 2 inches is mono-density and in thicknesses of 2.5 to 6 inches is dual-density. The unique dual-density insulation combines a high density outer layer and a more compliant, low density inner layer that are created simultaneously in our proprietary manufacturing process.


  • Non-combustible stone wool insulation with melting point of approximately 1177°C (2150°F)
  • Fire resistant due to its high melting temperature
  • Water and moisture resistant; does not absorb moisture to maintain insulating value Chemically inert
  • Does not rot, promote mildew, fungi, or bacteria
  • CFC- and HCFC- free product and process
  • Made from natural and recycled materials
  • ROXUL can contribute to earning LEED® points
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Technical Information

Property Test Standard Performance
Compliance ASTM C612 Mineral Fiber Block and Board Thermal Insulation - Type IVB Compliant
Compliance 236 - 05 - M MEA Approval, New York City Approval
Compliance For information on CAN/ULC S702 compliance, contact ROXUL Technical Support
Reaction to Fire ASTM E84 (UL 723) Flame spread index = 0 ; Smoke developed index = 0
Reaction to Fire CAN/ULC S102 Flame spread index = 0 ; Smoke developed index = 0
Reaction to Fire CAN/ULC S114 Determination of Non Combustibility of Building Materials - Non Combustible
Reaction to Fire ASTM E136 Behaviour of materials at 750°C - Non Combustible
Density (thickness: 1",1.5") Monolithic Density of 5.3 lbs/ft³ (85 kgs/m³) ASTM C303
Density (thickness ≤ 2") ASTM C303 Monolithic Density of 4.4 lbs/ft³ (70 kgs/m³)
Density (thickness ≥ 2.5") ASTM C303 Dual Density - 6.2 lbs/ft³ (100 kgs/m³) outer layer and 4.1 lbs/ft³ (65 kgs/m³) inner layer
Corrosion Resistance ASTM C795 Stress Corrosion Cracking Tendency of Austenitic Stainless Steel - Passed
Corrosion Resistance ASTM C665 Corrosion of Steel - Passed
Thermal Resistance ASTM C518 (C177) R-Value / inch @ 75oF 4.2 hr.ft2.F/Btu
Thermal Resistance ASTM C518 (C177) RSI value / 25.4mm @ 24oC 0.75 m2K/W
Reaction to Moisture ASTM C1104 Moisture Sorption - 0.03% by volume
Reaction to Moisture ASTM E96 Water Vapor Transmission, Desiccant Method - 1555ng/Pa.s.m2 (27 perm)
Reaction to Moisture ASTM C1338 Determination of Fungi Resistance - Passed
Thickness 1" (25.4mm) to 6" (152.4mm) offerings
Dimensions 24"x48" (610mm x 1219mm) and 16"x48" (406mm x 1219mm)
Acoustical Performance ASTM C423
Thickness 125 Hz 250 Hz 500 Hz 1000 Hz 2000Hz 4000 Hz NRC
1.5" 1.19 0.55 1.03 1.06 1.02 1.01 0.9
2" 0.26 0.71 1.14 1.09 1.04 1.03 1
3" 0.72 0.93 0.88 0.84 0.9 0.97 0.9
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