FeltBuster® High-Traction Synthetic Roofing Felt: Installation Guidelines and Best Practices

Roofing underlayment plays a critical role in protecting a home’s structure from water infiltration, weather exposure, and long-term degradation. Among the many materials available, GAF’s FeltBuster® High-Traction Synthetic Roofing Felt has emerged as a durable, high-performance option. This article provides a detailed and factual overview of the installation instructions and best practices for FeltBuster® as outlined in official documentation, including manufacturer guidelines, code compliance, and ventilation considerations.

Overview of FeltBuster® High-Traction Synthetic Roofing Felt

FeltBuster® High-Traction Synthetic Roofing Felt is a synthetic underlayment designed to offer enhanced durability, tear resistance, and high traction to prevent slippage. Unlike traditional asphalt-saturated felt, it is constructed using polypropylene, which provides greater resistance to tearing and moisture compared to conventional materials. This underlayment is often used in conjunction with asphalt shingles and is recognized for its ability to maintain a Class A fire rating when installed correctly.

According to manufacturer specifications, FeltBuster® must be installed over one layer of VersaShield® Fire-Resistant Roof Deck Protection to maintain the fire rating of GAF asphalt shingles. This combination ensures both structural integrity and compliance with fire safety codes.

Proper Installation Techniques

1. Ventilation Considerations

One of the key installation prerequisites for FeltBuster® is ensuring proper under-deck ventilation. The material retards moisture vapor movement, which can lead to condensation beneath the underlayment. Prolonged moisture exposure may result in mold growth, deck deterioration, and compromised roofing performance.

A design professional must review and address the potential for moisture entrapment. This may include the use of:

A continuous vapor barrier in the ceiling
Soffit and ridge vents
Gable vents
Power vents

Local building codes should be reviewed to ensure compliance with regional ventilation requirements. Inadequate ventilation can lead to long-term roofing issues, particularly in humid or high-moisture environments.

2. Laying Out the Underlayment

The FeltBuster® High-Traction Synthetic Roofing Felt should be installed parallel to the eaves of the roof. It is important to lay the material flat without wrinkles and to cap nail it in place. The underlayment should not be stretched during installation, as this can cause tearing or improper adhesion.

According to GAF installation instructions, each course of underlayment should be laid with a minimum overlap of 2 inches on the eaves and 6 inches on the ridges and hips. This ensures proper coverage and protection against water intrusion. The material should also be applied over the valley lining and extend at least 6 inches past the edge of the valley.

For the top course, a 6-inch lap over the ridge is recommended to ensure a watertight seal. The longer the roof deck remains exposed to the elements before shingles are applied, the more critical it is to ensure the underlayment is tightly sealed and properly overlapped.

3. Nailing and Fastening

Nailing is a critical step in the installation process. The bottom and middle of each course of underlayment should be secured with corrosion-resistant nails spaced every 6 to 8 inches. It is important to avoid walking on the underlayment before it is nailed in place, as this can cause shifting or wrinkling.

The top edge of the course does not need to be completely nailed, as it will become the bottom of the next course once additional layers are applied. However, a few nails should be used to hold the top in place temporarily.

When wrinkles or cuts are made during installation, it is recommended to apply a thin coat of asphalt-based roofing cement to waterproof the affected areas. This is especially important if the deck will be exposed to the weather for an extended period before shingles are applied.

4. Laying Lines and Overlaps

Lay lines are provided on the FeltBuster® product to help guide the installation. On slopes of 4/12 or greater, a single layer of underlayment is typically sufficient. Successive sheets should overlap by a minimum of 2 inches and be offset by at least 6 feet in successive rows. This staggered pattern helps prevent water from seeping through the seams.

For high-wind areas, fasteners should be spaced no more than 36 inches on-center along overlaps to provide additional security. This is particularly important in regions prone to severe weather conditions.

Code Compliance and Manufacturer Requirements

FeltBuster® High-Traction Synthetic Roofing Felt is approved and certified for use in various regions, including Florida (approval number FL10626R19) and Miami-Dade County. It is also covered under the Florida Building Code (FBC) under approval number FL18686R4.

The installation of FeltBuster® must be in strict compliance with the roof assembly’s Notice of Acceptance and the manufacturer’s published literature. For example, GAF’s 2-Part Roofing Adhesive must be applied in accordance with the Notice of Acceptance and the manufacturer’s guidelines when used in conjunction with FeltBuster®.

Additionally, the GF RoofPro felt application instructions require double coverage in all valleys, hips, and ridges. This helps ensure that these high-risk areas are adequately protected against water intrusion.

Best Practices and Recommendations

Several best practices have been outlined in industry guides and manufacturer documents to ensure optimal performance of FeltBuster® underlayment:

Double Coverage in Critical Areas: Valleys, hips, and ridges should be lined with a full width of roofing felt or bituminous membrane. This helps prevent leaks and ensures a watertight seal.
Offset Overlaps: Successive rows of underlayment should be offset by at least 6 feet to avoid creating a continuous seam that could allow water to penetrate.
Sealing Cuts and Wrinkles: Any cuts or wrinkles in the underlayment should be sealed with asphalt-based roofing cement to prevent water infiltration.
Proper Ventilation: Ensure that the roof assembly includes adequate ventilation, including soffit, ridge, and gable vents. This helps prevent moisture buildup and condensation.
Use with Approved Materials: FeltBuster® is designed to work in conjunction with other approved materials, such as VersaShield® Fire-Resistant Roof Deck Protection. It is important to follow all manufacturer guidelines and code requirements when combining materials.

Potential Challenges and Considerations

One potential issue with FeltBuster® is the risk of moisture entrapment. Because the material retards moisture vapor movement, it can lead to condensation beneath the underlayment, particularly in humid climates or during periods of high humidity. This can result in mold growth and deterioration of the roof deck if not properly managed.

To mitigate this risk, it is recommended to use a continuous vapor barrier in the ceiling and ensure that the roof includes adequate ventilation. Power vents, ridge vents, and gable vents can help reduce moisture buildup and improve air circulation.

Another consideration is the use of FeltBuster® in conjunction with ice and water shields. In some cases, it may be necessary to install an ice and water shield along the lower edge of the roof to prevent water from backing up under the underlayment and starter shingle course. This is particularly important in regions with heavy fog or condensation issues.

Warranty and Peace of Mind

GAF offers the option to add a limited lifetime warranty when FeltBuster® is installed with other qualifying roofing products. This provides homeowners with additional peace of mind and assurance that the underlayment will perform as intended for many years.

To qualify for the warranty, it is important to follow all manufacturer installation instructions and use only approved materials. This includes ensuring that the underlayment is installed over a suitable roof deck and that all ventilation and fastening requirements are met.

Conclusion

FeltBuster® High-Traction Synthetic Roofing Felt is a durable and high-performance underlayment that offers excellent protection against water intrusion, weather exposure, and long-term degradation. When installed correctly, it can significantly enhance the longevity and performance of a roof.

Proper installation requires careful attention to ventilation, overlapping, nailing, and fastening. It is also essential to follow all manufacturer guidelines and code requirements to ensure compliance and optimal performance.

By following best practices and using approved materials, homeowners and roofing professionals can ensure that their roofing systems remain durable, watertight, and code-compliant for many years to come.