Asphalt shingles remain one of the most popular roofing materials in the United States due to their durability, cost-effectiveness, and aesthetic versatility. Whether installing a new roof or replacing an existing one, following proper installation techniques is essential to ensure long-term performance and resistance to weather-related damage. This guide provides a detailed and structured overview of asphalt shingle installation, drawing from authoritative resources including manufacturer recommendations, technical specifications, and best practices for various environmental conditions.
Key Considerations for Asphalt Shingle Installation
Before beginning the installation process, it is important to understand the key factors that influence the performance and longevity of asphalt shingles. These include:
- Shingle Type and Quality: Asphalt shingles are categorized into three main types—strip shingles, dimensional shingles, and luxury shingles. Each type varies in cost, durability, and aesthetic appeal. Dimensional and luxury shingles often offer enhanced wind resistance and longer warranties.
- Climate and Weather Conditions: Cold weather, high winds, and wildfire-prone areas require specific installation techniques to ensure the roof remains secure and functional.
- Roof Deck Preparation: A properly sealed and reinforced roof deck is critical to preventing water intrusion and ensuring the structural integrity of the roof.
- Underlayment and Flashing: Underlayment provides an additional layer of waterproofing, while proper flashing around roof penetrations and intersections ensures no water pathways exist.
- Nailing and Fastening Techniques: Correct nailing patterns, nail placement, and the use of appropriate fasteners (e.g., galvanized or stainless steel) are essential for wind resistance and long-term durability.
Tools and Materials Required
A successful asphalt shingle installation requires the following tools and materials:
- Shingles: Choose a type and grade appropriate for the climate and expected wind loads.
- Roofing Nails: Use high-quality, corrosion-resistant nails as specified by the shingle manufacturer.
- Hammer or Nail Gun: A framing hammer or pneumatic nail gun is suitable for securing shingles.
- Roofing Felt or Synthetic Underlayment: This layer provides a waterproof barrier beneath the shingles.
- Roofing Tape: Used for sealing seams and joints.
- Utility Knife and Chalk Line: For cutting and aligning shingles.
- Ladder and Safety Harness: Essential for safe access and fall protection.
- Pry Bar: Required for removing old shingles during a roof replacement project.
Safety equipment such as gloves, goggles, and non-slip shoes should be worn at all times to protect the installer from injury.
Preparing the Roof Surface
A clean, dry, and properly sealed roof deck is the foundation of a successful shingle installation. The following steps are recommended:
- Remove Old Shingles: If replacing an existing roof, use a pry bar to strip off old shingles and nails. Ensure all debris is removed and disposed of properly.
- Inspect and Repair the Roof Deck: Check for damaged or rotting wood and replace any compromised sections to ensure a stable and level surface.
- Install Underlayment: Apply roofing felt or synthetic underlayment over the entire roof deck. This provides an additional waterproofing layer and helps prevent moisture intrusion.
- Seal Roof Deck Seams: Use tape, a self-adhered membrane, or synthetic underlayment to seal all seams in the roof sheathing. For cold climates, consider using a self-adhered membrane with a #15 felt bond break.
- Install Drip Edge and Flashing: Secure drip edge at eaves and rakes to prevent water from seeping under the shingles. Proper flashing should be installed at all roof penetrations, such as vents, chimneys, and skylights, and at roof-wall intersections.
Installing the Starter Strip
The starter strip is a critical first step in the shingle installation process, as it ensures proper alignment and securement of the first layer of shingles.
- Starter Strip Installation: Install the starter strip at the eaves and rakes using nails or by embedding it in roofing cement. A self-adhered starter strip is often recommended for ease of application and improved sealing.
- Separation of Starter Strips: Starter strips are typically packaged as two pieces per shingle and must be separated in the middle before installation.
- Secure Fastening: Ensure the starter strip is fastened properly according to the manufacturer's specifications, and avoid overdriving or underdriving the nails.
Laying and Nailing the Shingles
Once the starter strip is in place, the main shingle installation can proceed. Proper alignment, nailing, and spacing are essential for both appearance and durability.
- Start at the Eaves: Begin laying shingles at the bottom edge of the roof and work upward. Ensure each shingle is aligned with the starter strip.
- Use the Correct Nailing Pattern: Most asphalt shingles require four nails per shingle, with two nails placed in the nailing zone near each end. High-wind-rated shingles may require six nails per shingle.
- Avoid Staples: Staples should never be used for securing asphalt shingles. They are not strong enough and can lead to shingle loosening or failure.
- Drive Nails Properly: Nails should be driven flush with the shingle surface without over-driving, which can cause cracking or damage. Ensure nails are positioned within the designated nailing zones.
- Apply Roof Cement for Additional Securement: In high-wind areas or for enhanced protection, apply continuous bands of asphalt roof cement along the eaves, rakes, hips, ridges, and open valleys.
Special Considerations for Different Climates
Asphalt shingles can be installed in a variety of climates, but special precautions are necessary for certain conditions.
Cold Weather Installation
- Temperature Considerations: Asphalt shingles become less flexible in cold weather, which can increase the risk of cracking or breakage. Follow manufacturer guidelines regarding installation temperatures and storage recommendations.
- Handling and Storage: Store shingles in a warm, dry location before installation to maintain flexibility. Avoid bending, throwing, or dropping bundles in cold conditions.
- Nailing Techniques: Ensure shingles are flat before nailing to prevent nail breakage. Extra care should be taken when installing shingles in areas that require lifting or bending, such as hips, ridges, and valleys.
- Surface Safety: In winter, roofs can have nearly invisible ice or frost buildup, making installation hazardous. Work only when the surface is free of ice and frost.
High-Wind and Hurricane-Prone Areas
- High-Wind-Rated Shingles: Install shingles rated for high winds, following the IBHS Fortified Home standards for design wind speeds.
- Enhanced Securement: Use six nails per shingle and apply roof cement along key areas such as eaves, rakes, and valleys.
- Fastener Quality: In homes located within 3,000 feet of salt or brackish water, use hot-dip galvanized or stainless steel fasteners to prevent corrosion.
Wildfire-Prone Areas
- Fire-Resistant Materials: Choose Class A-rated fire-resistant materials such as fiberglass-reinforced asphalt shingles, fiber-cement shingles, or slate.
- Roof Design: Opt for a simple roof design with minimal overhangs or features that can trap embers. Ensure proper underlayment and flashing are in place to prevent fire spread.
High-Snow-Load Regions
- Ice Dam Prevention: Install self-adhering bituminous membrane along eaves and ensure proper attic insulation and ventilation to reduce the risk of ice dams.
- Drip Edge and Flashing: Ensure drip edge and flashing are properly installed to manage snow melt and prevent water intrusion.
Advanced Installation Techniques
Certain roof features require specific installation methods to ensure proper coverage and securement.
Rake Installation
- Flashing Cement Application: Shingles at rakes should be set in a minimum 8-inch-wide strip of compatible flashing cement, with a maximum thickness of 1/8 inch.
- Starter Strip Option: An optional manufacturer-approved starter strip can be set in a similar strip of flashing cement, ensuring it does not extend beyond the drip edge.
Valley Installation
- Flashing Cement and Cut Edges: Shingles installed at open valleys must be set in a minimum 8-inch-wide strip of flashing cement. Closed valley cut edges require a minimum 2-inch-wide strip.
- Manufacturer Specifications: Always follow the manufacturer's specifications for valley installation, as techniques may vary depending on the shingle type.
Ridge and Hip Installation
- Hip and Ridge Shingles: These are specially shaped to cover the peaks and intersections of the roof. Install them using the same nailing and cement application techniques as standard shingles.
- Overlap and Securement: Ensure proper overlap and securement to prevent wind uplift and water intrusion.
Maintenance and Inspection
After installation, regular inspection and maintenance are important to ensure the roof remains in optimal condition.
- Annual Inspection: Inspect the roof annually for signs of damage, such as missing shingles, curling edges, or leaks.
- Clean Gutters and Drainage Areas: Ensure gutters and downspouts are free of debris to prevent water accumulation.
- Repair Promptly: Address any issues immediately to prevent further damage and extend the roof's lifespan.
Conclusion
Asphalt shingle installation is a complex and critical process that requires attention to detail, adherence to manufacturer guidelines, and awareness of environmental factors. By following the outlined steps and recommendations, homeowners and contractors can achieve a durable, weather-resistant roof that provides long-term protection and aesthetic value. Proper preparation, correct nailing techniques, and special considerations for extreme weather conditions are essential to maximizing the performance and longevity of an asphalt shingle roof.