GlasRoc® Interior Drywall is a high-performance interior gypsum panel with a special formulation, treated core, and fiberglass mat facer technology, designed to provide exceptional moisture and mold protection for interior applications and exterior soffits. Its innovative, off-white face panel and tapered edges allow for superior indoor finishing and decorating results. GlasRoc Interior is GREENGUARD Gold certified. Also available in 5/8” Type X, which is reinforced with fiberglass for increased strength and fire resistance. 

GlasRoc Interior offers superior resistance to incidental moisture and can provide protection in most applications from exposure to indirect environmental elements. It scores, cuts, and fastens easily, and has a specially coated front facer to provide irritation-resistant handling. It is designed for use in applications that require direct mechanical attachment to wood or metal framing. 

The 5/8” Type X offering is designed as a component of fire-rated assemblies. To ensure optimum Type X fire resistance performance, follow recommended installation procedures for fire-rated assemblies. When used in a certified sound-rated assembly, GlasRoc Interior Type X will also contribute to required sound transmission classification (STC) values. 

Technical Information

Surface Burning Characteristics: UL classified for surface burning (File No. R3660) (per ASTM E84 and CAN/ULC-S102) Flame spread = 0; Smoke developed = 0; Meeting Class A Ratings. Core combustibility (per ASTM E136 and CAN/ULC-S114) Non-combustible.  

5/8" Type X is UL classified for fire resistance per ASTM E119 and CAN/ULC-S101. File No. R3660, Type GlasRoc.  

Applicable Standards and References: Manufactured to meet ASTM C1658/ C1658M, Section 7, Type X (for 5/8") and ASTM D3273 for mold resistance. Meets properties of ASTM C1396/C1396M. Install according to ASTM C840 and Gypsum Association GA-216. 


Limitations: GlasRoc Interior should not be used where temperatures exceed 125°F for extended periods or in areas of extreme humidity.

GlasRoc Interior is not for use as a tile backer in shower, tub and other wet areas. It may be used as a tile backer in dry areas. 

GlasRoc Interior is not designed as a nailing base. Mechanical fastening should pass through GlasRoc and fasten to the framing members. Do not immerse GlasRoc in water or subject to cascading water. 

*GlasRoc Interior provides extra resistance against the formation of mold, but no product may be considered “mold proof.” The most effective way to avoid the formation of mold and mildew in drywall products is to limit or avoid water exposure during storage and construction, and after construction is complete. Used in combination with appropriate design, handling, construction and installation practices, GlasRoc drywall can provide increased mold and mildew resistance on its surface. ASTM D3273 is the “Standard Test Method for Resistance to Growth of Mold on the Surface of Interior Coatings in an Environmental Chamber” and is performed under controlled laboratory conditions. Actual storage, handling, construction and installation conditions may vary from the environment created in the independent lab, and the use of the product in actual conditions may not replicate the ASTM results.

Stack flat, keep dry and lift (do not drag) to avoid scuffing. Avoid damage to edges. For detailed recommendations, refer to GA-216 and GA-801. 

Interior Walls and Ceilings: Treat joints with either paper joint tape and ready mix compound or fiberglass mesh tape and setting compound. Skim entire panel with compound to achieve a smooth finish. Overpaint with an interior-grade primer and two coats of interior-grade paint applied to manufacturer’s recommendations. 

Exterior Soffits: (Method 1) Treat joints with fiberglass-mesh tape and setting compound, overpaint with an exterior-grade primer and two coats of exterior-grade paint. (Method 2) When used as part of an EIFS system, treat and finish joints as recommended by the EIFS manufacturer. 

Safety Precautions: Wear safety glasses and NIOSH-approved respirators during cutting, breaking, rasping or other dust-producing activities. Safety Data Sheets (SDS) are available for all CertainTeed products.

Warranty Details

Please see the attached document 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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