GlasRoc® Sheathing is the industry standard for high-quality Type X gypsum-based exterior sheathing. 

Available in both 1/2" (12.7 mm)* and 5/8" (15.9 mm) thickness, GlasRoc Sheathing is made with cementitious glass mat facers that are embedded into a water-resistant gypsum core. This provides a surface that is ideal for long-term protection against weather exposure. 

Strong, lightweight, and flexible, GlasRoc Sheathing allows for bending to curved surfaces. It also cuts like regular gypsum board, but with minimal skin irritation due to embedded glass mat.


  • Long-term protection (12 months) to weather exposure
  • Water-resistant surface does not inhibit water vapor permeance
  • Mold- and moisture-resistant
  • Compatible with most exterior wall systems and applications
  • Excellent fire-resistance properties, and numerous fire-rated assemblies
  • Conformity to design and code requirements
  • 12-month limited warranty against exposure
  • 5-year limited product performance warranty
  • 12-year substrate limited warranty in architecturally specified EIF Systems


For more details, see the Product Data and Submittal Sheet found under the technical information tab.


*Contact your customer service representative to confirm availability in your region. 


Technical Information

Product Data

  • Thicknesses: 1/2"*, 5/8" (12.7 mm*, 15.9 mm)
  • Width: 4' (1220 mm) standard
  • Length: 8' (2440 mm) standard (custom lengths available)
  • Edges: Square
  • Packaging: Per piece

Surface Burning Characteristics

GlasRoc Sheathing panels have a Flame Spread rating of 0 and Smoke Development rating of 0, in accordance with ASTM E84 (CAN/ULC-S102)


Non-combustible when tested inaccordance with ASTM E136 (CAN/ULCS114).

Fire Resistance

Fire resistance tests are conducted in accordance with ASTM E119 (ANSI/UL 263 and CAN/ULC-S101) and no warranty is made other than conformance to the standard under which the assembly was tested. Minor discrepancies may exist in the values of ratings, attributable to changes in materials and standards, as well as differences between testing facilities. Assemblies are listed as “combustible” (wood framing) and “noncombustible” (concrete and/or steel construction). For fire resistance ratings, refer to the Gypsum Association Fire Resistance Design Manual, UL Fire Resistance Directory - Vol. 1, and ULC Fire Resistance Directory (List of Equipment and Materials).

UL/ULC Type Designations

Applicable Standards and References

  • Manufactured to meet ASTM C1177 and applicable sections of ASTM C1396.
  • ASTM E2178 (CAN/ULC-S741) Air Barrier Materials.
  • Component of ASTM E2357 (CAN/ ULC-S742) Air Barrier Assemblies.
  • UL Evaluation Report UL ER3660-01.


Store materials protected against damage from weather, direct sunlight, surface contamination, construction traffic, or other causes. Stack sheathing flat on level supports off the ground, under cover and fully protected from weather. Store and support panels in flat stacks to prevent sagging. Protect materials to keep them dry. Protect panels to prevent damage to edges and surfaces. Comply with Gypsum Association GA-801.

*Contact your customer service representative to confirm availability in your region. 



Comply with Gypsum Association GA-253, ASTM C1280, manufacturer’s written instructions and local building codes. Cut panels at penetrations, edges and other obstructions; fit tightly against abutting constructions, unless otherwise indicated. Install panels with a 3/8" (9 mm) setback where nonload-bearing constructions abuts structural elements. Install panels with a 1/4" (6 mm) setback where they abut masonry or similar materials that might retain moisture, to prevent wicking. Coordinate GlasRoc Sheathing installation with flashing and joint sealant installation so these materials are installed in
sequence and in a manner that prevents exterior moisture from passing through the completed exterior wall assembly. Apply fasteners so heads bear tightly against face of the GlasRoc Sheathing panels but do not cut into the facers.

Do not bridge building expansion joints with GlasRoc Sheathing; cut and space edges to match spacing of structural support elements. GlasRoc Sheathing is not intended for water immersion. Any cascading water should be directed away from the GlasRoc Sheathing until the appropriate drainage is in place. The use of forced air heaters creates water vapor. Proper venting is necessary to reduce potential condensation of this water vapor on building materials. CertainTeed is not responsible for damage resulting from use of these types of heaters. The heater manufacturer should be consulted for proper use and ventilation procedures. Other conditions that may create moisture in the air, reduce drying potential or cause condensation on GlasRoc Sheathing should be avoided. Do not allow water to pond or settle on GlasRoc Sheathing. Exposed wall ends should be covered to prevent water infiltration.

Horizontal Installation

Install GlasRoc Sheathing with long edges in contact without forcing. Abut ends of panels over centers of stud flanges, and stagger end joints of adjacent panels not less than one stud spacing. Attach panels at perimeter and within field of panel to each stud. Space fasteners a maximum of 8" (200 mm) o.c. (tighter spacing if recommended by manufacturer for specific application or UL/ULC fire-rated assembly details) and a minimum of 3/8" (9 mm) from edges and ends of panels. Treat panel joints, when required by local building code or exterior finish system, per manufacturer’s written instructions. No joint treatment or weather-resistant barrier is required for the applicability of the GlasRoc product exposure warranty.

Warranty Details

CertainTeed provides a 12 month limited warranty against exposure and a 5 year limited warranty assuring product performance.

Please see the attached documents for complete warranty details.

Sustainability Information

CertainTeed takes pride in providing the best solutions to make the spaces where we work, live, and play healthier and safer. This means offering high-performing products that create better living environments.

Our products improve building energy efficiency and reduce building energy consumption for the life of the structure. As a result, they help conserve nonrenewable energy sources, decrease dependence on hydrocarbons and lower greenhouse gas emissions.

CertainTeed’s ongoing commitment to sustainability in our manufacturing operations incorporates the principles of industrial ecology, managing energy and water, and reducing waste.


Our ecomedes Sustainable Product Platform allows you to quickly access the product information and certifications you need, calculate contributions to LEED and other green building rating systems and create and save a group of products using the project feature. The information is free to access and always up to date.

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