Continuous Insulation for Optimal Thermal Performance

ROXUL CAVITYROCK® MD and CAVITYROCK® DD are high-density semi-rigid board insulation products designed for external cavity wall and rainscreen applications. This board insulation combined with the COMFORTBATT® thermal batt insulation in the exterior wall stud cavity offers superior long-term thermal efficiency, fire resistance, moisture control, and acoustic performance.

ROXUL CAVITYROCK® Rainscreen System

Engineered for strength, designed for efficiency, ROXUL CAVITYROCK®’s semi-rigid insulation board is built for commercial cavity wall applications. Water repellent, sound absorbent and non-combustible insulation, ROXUL stone wool provides longstanding effective thermal insulation for the building envelope.

CAVITYROCK® is widely compatible with air/vapour barriers, wall ties and fasteners.

Mono and Dual Density Insulation Boards for the Building Envelope

CAVITYROCK® MD offers powerful single-density insulation for cavity walls, available in 1 to 2 inch thicknesses to suit your specifications.

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CAVITYROCK® DD combines a high-density outer layer for increased durability and water repellence with a less dense inner layer, equipped for a flexible fit and superior thermal resistance.

Thermal Insulation

Specifically designed as a commercial cavity wall and rainscreen solution, CAVITYROCK® stone wool insulation board provides high-performance thermal insulation as well as reliable protection from the elements throughout subsequent thermal cycles.

Thermal Resistance and R-value

Dimensionally stable ROXUL delivers continuous thermal resistance and consistent R-value for your climate zone requirements. ROXUL has a lesser thermal expansion co-efficient than foam plastic alternatives, demonstrating inorganic stone wool’s resistance to shrinkage, leaks and unpredictability that can negatively affect organic material over time. ROXUL mineral wool insulation provides stability and weather resistance, combatting thermal loss and promoting optimal energy efficiency long term.

Moisture Management

CAVITYROCK® is water repellent, yet vapour permeable, promoting effective drainage and rapid drying. Low sorption stone wool insulation will not wick or retain moisture, allowing it to maintain its shape and integrity. ROXUL is a natural, chemically inert and inorganic product. It resists rot and corrosion, as well as the growth of mildew, bacteria and fungi.

Fire Protection

Fire resistant ROXUL stone wool insulation resists heat transfer and helps prevent fire damage. Classified as non-combustible insulation by ASTM E136 and CAN4-S114, the installation of a fire-stop is not required.

ROXUL’s extremely high melting point of 2150 ◦F (1170◦C) slows the spread of flame in the event of fire. And, unlike foam insulation, stone wool does not produce toxic smoke.

Acoustical Performance

The BEDR™ Wall System

Used in combination with ROXUL COMFORTBATT® thermal batt, CAVITYROCK® is part of the complete BEDR™ wall rainscreen system for long-term thermal performance, fire protection, water repellence and sound absorbency.

Sustainable Design

ROXUL is innovation for the future of sustainable development. Made from naturally occurring basalt rock and recycled slag, ROXUL stone wool insulation is the choice for environmentally-conscious architects.

ROXUL is committed to ecological manufacturing practices. Our products are third party certified allowing some of them to contain up to 40% recycled content.  Consult a ROXUL representative to find out how building projects using ROXUL products qualify for LEED® (Leadership in Energy and Environmental Design) credits.


This product is specifically designed for use in cavity  wall and rainscreen applications.

Product variations:
CavityRock MD
(mono density) delivers an R-value/inch of 4.2 and is available in thicknesses of up to 2 inches.

CavityRock DD - For assemblies requiring higher R-values, ROXUL's exclusive, dual density CavityRock DD delivers an R-value of 4.3/inch in thicknesses of 2.5 to 5 inches. This unique 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 approx. 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