DensGlass is a high-performance, moisture- and mold-resistant exterior sheathing material used in a wide range of construction applications, including exterior walls, roof assemblies, and fire-rated systems. Manufactured by Georgia-Pacific, DensGlass is designed to withstand the rigors of exterior environments while maintaining structural integrity and durability. Its gold-colored surface and fiberglass-reinforced gypsum core make it a preferred choice for builders seeking a long-lasting and reliable solution for residential, commercial, and industrial projects across the United States.
This guide provides a comprehensive overview of DensGlass installation procedures, including surface preparation, cutting techniques, panel positioning, fastening methods, joint sealing, and safety considerations. The information is derived from official installation instructions and technical specifications provided by Georgia-Pacific and other relevant sources.
Overview of DensGlass Features and Benefits
DensGlass is engineered to offer superior resistance to moisture and mold, making it an ideal choice for exterior applications where traditional gypsum sheathing might be prone to damage. Its fiberglass mat face and high-density core help prevent water absorption, while its design supports long-term structural performance. In addition, DensGlass is compatible with a variety of cladding systems, including brick, stucco, fiber cement, metal panels, and wood sidings.
The material is also suitable for use in fire-rated assemblies, provided that installation follows the guidelines outlined in the UL Fire Resistance Directory or the Gypsum Association’s GA-600. Proper installation is critical to ensuring that DensGlass performs as intended and meets local building codes.
Preparing the Surface for Installation
Before installing DensGlass panels, it is essential to ensure that the framing structure is properly prepared. The framing should be level, plumb, and free from debris. Any defects in the framing materials, such as warping or misalignment, should be corrected prior to sheathing installation.
Stud spacing must adhere to local building codes, typically ranging between 16 inches and 24 inches on center. DensGlass panels should be stored off the ground and away from standing water to prevent moisture damage before installation.
Cutting DensGlass Panels
Cutting DensGlass requires precision to ensure a secure fit and to maintain the integrity of the fiberglass mat. A utility knife or gypsum board cutter should be used to score the face of the panel along the desired cut line. Once scored, the panel can be snapped along the line to create a clean break.
After snapping, any excess fiberglass edges should be trimmed using a razor blade to ensure a smooth, even surface. Overcutting should be avoided, as it can lead to a poor fit and potential gaps during installation. Careful cutting ensures that panels align properly with adjacent panels and framing members.
Positioning DensGlass Panels
DensGlass can be installed either horizontally or vertically, depending on the project specifications and the desired aesthetic or structural outcome. A 1/8-inch gap should be left between adjacent panels to allow for expansion and contraction due to temperature and humidity changes. This gap helps prevent warping or buckling over time.
When positioning panels, it is important to ensure that the edges align properly with both adjacent panels and the framing members. Panels should be installed snugly around all openings, such as windows and doors, and butted over the center of framing members for vertical installations. In non-load-bearing applications, a 3/8-inch gap should be left where the sheathing abuts structural elements.
Fastening the Sheathing
DensGlass should be fastened using approved galvanized screws, nails, or staples as recommended by Georgia-Pacific. Fasteners should be spaced at intervals of 8 inches along panel edges and 12 inches in the field. It is important to avoid overdriving fasteners, as this can damage the fiberglass surface and reduce the panel’s performance.
For horizontal applications, end joints should be staggered to enhance the structural stability of the installation. In fire-rated assemblies, the orientation of the panels should be selected based on the design requirements outlined in the UL Fire Resistance Directory or GA-600.
Sealing Joints and Penetrations
To ensure the sheathing system is weather-resistant, all panel seams should be sealed with a weather-resistant joint sealant. This helps prevent air and moisture infiltration, which can compromise the integrity of the building envelope.
In addition, self-adhesive flashing tape should be applied around windows, doors, and other penetrations. This tape provides an additional layer of protection against water intrusion and helps maintain the airtightness of the building.
For areas where DensGlass abuts masonry or other moisture-retaining materials, a 1/4-inch gap should be left to prevent wicking of moisture. Similarly, a 3/8-inch gap is recommended for non-load-bearing abutments.
Compatibility with Cladding Systems
DensGlass is compatible with a wide range of exterior cladding materials, making it a versatile solution for various construction projects. It can be used as a base for brick and stone veneer, stucco and EIFS (Exterior Insulation and Finish System), fiber cement and metal panels, and wood and composite sidings.
When installing insulation behind DensGlass, it is important to follow the recommended practices to prevent condensation. Batt or blanket ceiling insulation should be installed before the panels if a vapor retarder is being used. Loose-fill insulation should be applied immediately after panel installation.
Safety Considerations
Working with DensGlass requires the use of appropriate personal protective equipment (PPE) to ensure the safety of installers. Long pants and a long-sleeved, loose-fitting shirt should be worn to protect against skin irritation from fiberglass fibers. Protective gloves and safety goggles with side shields are also necessary to prevent eye and hand injuries.
A dust mask should be worn when sanding, and additional respiratory protection may be required in highly dusty environments. It is important to avoid direct contact with the skin and eyes and to avoid breathing in dust or fibers during installation.
Installers should also be cautious when cutting the material and should refrain from using power saws, which can release excessive amounts of dust and fibers into the air. A utility knife or gypsum board cutter is the recommended cutting method.
General Installation Guidelines
Installation of DensGlass should follow the guidelines outlined in ASTM C840 and GA-216. Panels should be applied at right angles to framing members, with the maximum number of end joints minimized by using the longest practical panel lengths. Panel edges should be brought into contact with each other but should not be forced into place.
When working with insulation, it is important to ensure that installation practices do not promote condensation behind the panels. Proper ventilation and insulation placement are essential to maintaining the performance of the sheathing system.
Conclusion
DensGlass is a high-performance exterior sheathing material that offers excellent moisture and mold resistance, making it a reliable choice for a wide range of construction projects. Proper installation is essential to ensuring the material performs as intended and meets local building codes. By following the outlined procedures for surface preparation, cutting, positioning, fastening, and sealing, builders can achieve a durable and weather-resistant sheathing system.
When installed correctly, DensGlass supports structural integrity, enhances energy efficiency, and provides long-term durability. Its compatibility with various cladding systems makes it a versatile solution for both residential and commercial construction. By adhering to the manufacturer's guidelines and best practices, installers can ensure that their projects meet the highest standards of quality and performance.