The Grace Perm-A-Barrier Wall Membrane is a critical component in air and water barrier systems designed to protect building envelopes from environmental exposure. This fully adhered membrane system is used in conjunction with other Grace products, such as the PERM-A-BARRIER® Detail Membrane and BITUTHENE® Primer B2 LVC, to ensure a durable, high-performance air barrier assembly. The installation process, material specifications, and application guidelines are outlined in detail in official documentation from GCP Applied Technologies, Inc., the manufacturer of the product.
This article provides a comprehensive overview of the installation process, technical specifications, and key considerations for using the Perm-A-Barrier Wall Membrane in U.S. construction projects. The information is derived directly from the manufacturer’s official product documentation, ensuring accuracy and relevance for contractors, building professionals, and DIY enthusiasts.
Installation Overview
The Perm-A-Barrier Wall Membrane is designed for application on primed substrates, typically gypsum sheathing or blockwork with masonry anchors. It is important to follow precise surface preparation and application techniques to ensure the membrane adheres properly and functions as intended.
Surface Preparation
Before applying the Perm-A-Barrier Wall Membrane, the substrate must meet specific conditions:
- The surface must be smooth, clean, dry, and free of voids, spalled areas, loose aggregate, loose nails, sharp protrusions, or other materials that might interfere with adhesion.
- Any loose dust or dirt should be removed by wiping the surface with a clean, dry cloth or brush.
- If the substrate is damp, it must be allowed to dry, or BITUTHENE® Primer B2 LVC should be applied to prepare the surface for membrane installation.
The surface temperature and air temperature must be at least 25°F (-4°C) and rising to ensure proper adhesion.
Cutting and Application
The membrane should be cut into manageable lengths for ease of handling. It can be applied either horizontally or vertically, depending on the construction layout and the presence of masonry anchors.
- When applying the membrane to blockwork with projecting masonry anchors (ties), the installation should begin at the base of the wall.
- Each sheet of membrane must be installed such that the upper edge runs continuously along the underside of the line of anchors.
- Subsequent sheets should overlap the sheet below by at least 2 inches (51 mm), directly below the line of anchors.
- If the membrane width of 18 inches (457 mm) is wider than the spacing between anchor lines (typically 16 inches or 406 mm), the membrane should be cut at the location of the tie wires to allow for proper placement.
Pressing and Sealing
Once applied, the membrane must be pressed firmly into place using a hand roller or the back of a utility knife. This step is critical to ensure continuous and intimate contact with the substrate, preventing water from migrating under the membrane.
All non-water-shedding edges must be sealed using PERM-A-BARRIER® Universal Flashing & Sealant, BITUTHENE® Liquid Membrane, or BITUTHENE® Mastic. Proper sealing is essential to maintain the integrity of the air and water barrier system.
Technical Specifications and Performance
The Perm-A-Barrier Wall Membrane is engineered to meet rigorous performance standards, including resistance to water vapor transmission, air permeance, and mechanical durability. These specifications are tested and verified under standardized ASTM methods and are detailed in the manufacturer’s documentation.
Key Performance Metrics
| Property | Specification | Test Method |
|---|---|---|
| Minimum elongation to failure (rubberized asphalt) | 200% | ASTM D412 die C modified |
| Pliability at 180° bend over 1 in. (25 mm) mandrel | Pass at -25°F (-32°C) | ASTM D1970 |
| Nail sealability | Pass | ASTM D1970 |
| Crack cycling, 1/8 in. (3.2 mm) at -25°F (-32°C) | Unaffected | ASTM C836 |
| Minimum puncture resistance (membrane) | 40 lbs (178 N) | ASTM E154 |
| Lap peel adhesion at minimum application temperature | 4 lbs/in. width (700 N/m) | ASTM D1876 modified |
| Maximum permeance to water vapor transmission | 0.05 perms/(Pa·s·m²) (2.9 ng) | ASTM E96 method B |
| Air permeance of in-place membrane | 0.0002 cfm/ft² (<0.001 L/s/m²) | ASTM E2178 |
| Assembly air permeance at 1.57 psf (75 Pa) pressure difference | <0.0008 cfm/ft² (<0.004 L/s/m²) | ASTM E2357 |
| Water absorption (weight gain at 24 hours) | 0.1% | ASTM D570 |
| UV exposure limit | 90 Days | N/A |
These metrics indicate that the membrane provides excellent resistance to air and water infiltration, making it suitable for use in a variety of climates and building types. The material is also designed to maintain performance in extreme temperatures, with a pliability test pass at -25°F (-32°C).
Air and Water Vapor Transmission
The Perm-A-Barrier Wall Membrane is designed to minimize air and water vapor flow, which is essential for maintaining the thermal performance of the building envelope and preventing moisture-related damage. The membrane has a maximum water vapor permeance of 0.05 perms/(Pa·s·m²), which aligns with Class III vapor barrier classifications.
The air permeance is measured at 0.0002 cfm/ft², ensuring that the membrane effectively restricts air movement through the building envelope. When tested as part of an assembly under a 1.57 psf (75 Pa) pressure differential, the air permeance remains below 0.0008 cfm/ft², demonstrating its high-performance barrier capabilities.
Safety, Storage, and Handling
Given the chemical nature of the mastic and solvent-based primer used in conjunction with the Perm-A-Barrier Wall Membrane, proper safety precautions must be followed during installation.
- Vapors from the mastic and primer are harmful and flammable, so appropriate personal protective equipment (PPE) should be worn.
- Users must familiarize themselves with the product labels and Safety Data Sheets (SDS) before use.
- SDS documents are available on the manufacturer’s website at gcpat.com or by contacting customer service at +1 (877) 423 6491.
- It is important to store the membrane and associated materials in a dry, secure location to prevent damage or degradation.
Repairs and Maintenance
In the event of damage or defects, the membrane can be repaired using a patch of Perm-A-Barrier Wall Membrane that extends 3 inches (75 mm) beyond the affected area in all directions. The patch must be pressed into place with a hand roller to ensure intimate contact with the substrate.
When sealing the repair, the following guidelines should be followed:
- If the patch is placed in a diamond pattern, both water-shedding edges must be sealed.
- If the patches are placed straight, the top edge and a minimum of 3 inches (75 mm) down each side must be sealed.
- If the sealing patch is horizontal, all edges must be sealed.
For small gaps (less than 1/8 inch or 3.2 mm in diameter), the repair should be covered with PERM-A-BARRIER® Universal Flashing & Sealant, extending 2 inches (51 mm) from the gap.
Membrane Protection During Construction
The Perm-A-Barrier Wall Membrane must be protected from damage caused by other trades or construction activities. Any physical contact with tools, equipment, or materials that could puncture or tear the membrane should be avoided. Once installed, the membrane is a critical component of the building envelope and must remain intact to function as intended.
Environmental and Compliance Considerations
The Perm-A-Barrier Wall Membrane is a rubberized asphalt-based material, which is known for its long-term durability and resistance to UV exposure (up to 90 days). However, prolonged exposure to direct sunlight without protection can degrade the material, so it is important to cover the membrane during construction if it remains exposed for extended periods.
The product is registered and compliant with U.S. building codes and standards, including those related to air and water barriers, energy efficiency, and occupant comfort. The manufacturer emphasizes that the information provided in the product documentation is based on the best available data and should be verified in conjunction with local building codes and conditions.
Conclusion
The Grace Perm-A-Barrier Wall Membrane is a high-performance air and water barrier system designed to protect building envelopes from environmental exposure. When installed correctly, it provides excellent resistance to air and water infiltration, enhancing the thermal efficiency, durability, and comfort of the structure. The product is backed by detailed technical specifications and application guidelines that ensure consistent performance across a range of construction applications.
For users, the key to success lies in strict adherence to surface preparation, application, and sealing protocols, as well as proper safety and storage practices. By following the manufacturer’s instructions and using the recommended materials, professionals can ensure that the Perm-A-Barrier Wall Membrane performs as intended for the life of the building.