Asphalt shingles remain one of the most popular roofing materials in the United States due to their durability, cost-effectiveness, and wide range of design options. Whether you are building a new home or replacing an existing roof, understanding the proper installation techniques is essential to ensuring longevity, weather resistance, and compliance with local building codes. This guide provides a detailed, step-by-step approach to installing asphalt shingles based on verified technical instructions from official roofing standards, manufacturer recommendations, and industry best practices.
Key Considerations Before Installation
Before beginning the installation of asphalt shingles, it is crucial to assess several foundational elements to ensure the roof performs optimally and meets safety and durability requirements.
1. Roof Deck Preparation
The roof deck is the structural base that supports the roofing system. According to the documentation, the roof deck must be sealed to prevent water intrusion. Three sealing methods are recommended:
- Install a self-adhered membrane over the entire roof deck, with a #15 felt bond break between the membrane and the shingles.
- Apply 4-inch-wide roof deck flashing tape over all panel seams and cover with #30 felt or synthetic underlayment.
- Use a two-layer #30 felt underlayment system.
In all cases, the underlayment should be sealed using tape or roofing cement where necessary. This is particularly important in high-wind or hurricane-prone regions to reduce the risk of water infiltration and shingle displacement.
2. Drip Edge Installation
Drip edges are metal strips installed along the eaves and rakes of the roof. They serve to direct water away from the roof edges and prevent water from seeping into the fascia or soffit. Proper installation of drip edges is critical for drainage and to reduce the risk of water damage over time.
According to the documentation, the starter strip—a narrow strip of shingle material—should be installed at the eaves and rakes. It should extend ¼ to ¾ inches beyond the drip edge to allow for proper drainage. The starter strip also plays a key role in sealing the first layer of shingles and preventing wind uplift.
3. Flashing and Penetration Sealing
Roof penetrations, such as chimneys, vents, and skylights, must be properly flashed to prevent water from entering the roof system. Flashing involves applying metal or rubber seals around these openings to create a watertight barrier. The documentation emphasizes the importance of integrating flashing with the underlayment and roof coverings for maximum effectiveness.
Additionally, all roof-wall intersections should be flashed to prevent water from entering at the junctions between the roof and walls.
4. Shingle Selection
Asphalt shingles come in three primary types, each with distinct characteristics:
- Strip shingles (3-tab): The most basic and cost-effective option, offering minimal wind resistance and a uniform appearance.
- Architectural shingles: Heavier and more durable, with a dimensional appearance that mimics materials like wood or slate. These are often recommended for regions with high winds or extreme weather conditions.
- Luxury shingles: The most advanced type, offering enhanced aesthetics, durability, and wind resistance.
The documentation recommends using high-wind-rated shingles in areas with strong wind conditions to reduce the risk of shingle displacement. Additionally, impact-resistant and solar-reflective shingles may be considered to enhance protection against hail and heat.
Step-by-Step Asphalt Shingle Installation
Once the roof deck and underlayment are properly prepared, the actual shingle installation can begin. This process should be followed carefully to ensure uniform coverage, proper nailing, and long-term durability.
1. Install the Starter Strip
The starter strip is a critical component of the roofing system, as it prevents water from seeping underneath the first course of shingles. The starter strip should be installed along the eaves and rakes, with the self-adhesive seal strip facing upward toward the eave edge.
- The starter strip should overhang the drip edge by ¼ to ¾ inches to allow for proper drainage.
- At the rake (the upper edge of the roof), the starter strip should overlap the starter strip at the eaves by 3 inches to maintain a continuous seal.
- It should be nailed 2 to 3 inches up from the bottom of the eave, using the number and type of nails specified by the manufacturer.
Some starter strips come in two pieces per shingle and must be separated in the middle before installation.
2. Install the First Course of Shingles
After the starter strip is in place, the first course of full shingles can be installed. The shingles should be laid in the same direction as the starter strip to ensure proper alignment.
- Six nails per shingle are typically required for secure attachment, though the exact number and placement should follow the manufacturer’s instructions.
- Nails should be driven just beneath the adhesive strip, ensuring they are flush with the shingle surface without being overdriven or underdriven.
A common mistake during installation is improper nailing, such as high or low nails, angled nails, or insufficient nailing. These can compromise the integrity of the roofing system and increase the risk of wind uplift or water infiltration.
3. Continue Laying Shingles in Courses
Each subsequent course of shingles should be installed with proper overlap and alignment. A chalk line can be used to ensure straight rows, particularly when working on large or complex roof surfaces.
- Shingles should be nailed just below the adhesive strip, with each row overlapping the one below it by the recommended amount (typically 1 to 1.5 inches).
- It is important to avoid bending or throwing bundles of shingles, especially in cold weather, as this can cause cracking or breaking.
- Shingles should be installed flat and even, avoiding any warping or curling that could affect their performance.
4. Special Handling in Cold Weather
Asphalt shingles can be installed in cold weather, but special precautions are necessary to ensure proper adhesion and durability. The documentation outlines several key considerations for cold-weather installation:
- Follow the manufacturer’s cold-weather instructions, which may include specific temperature ranges and storage recommendations.
- Avoid bending or lifting shingles in cold conditions, as they become more brittle and prone to cracking.
- Store shingles indoors prior to installation to maintain flexibility and reduce the risk of damage during handling.
- If shingles need to be lifted or bent (e.g., for hip or ridge applications), extra care should be taken, and warming methods may be necessary to prevent breakage.
5. Install Ridge and Hip Shingles
The final step in the installation process involves covering the ridges and hips of the roof. These areas are particularly vulnerable to water infiltration and wind uplift, so proper sealing is essential.
- Ridge and hip shingles should be cut to fit the specific angles and contours of the roof.
- They should be installed with a self-adhesive strip that bonds to the shingle below, creating a watertight seal.
- Nailing should follow the manufacturer’s specifications, with care taken to avoid damaging the shingle surface or causing misalignment.
Safety and Compliance
Safety is a critical aspect of asphalt shingle installation, particularly when working on sloped roofs or in cold weather conditions. The following safety considerations should be observed:
- Use a roofing harness and ladder to prevent falls and ensure stable footing.
- Avoid working on icy or frost-covered surfaces, as these can create hazardous conditions and increase the risk of slips or injuries.
- Follow local building codes and HOA guidelines, as some areas may have specific requirements regarding shingle type, color, or installation methods.
Compliance with these standards not only ensures a safe working environment but also helps maintain the structural integrity and longevity of the roofing system.
Conclusion
Asphalt shingle installation is a complex process that requires careful planning, proper technique, and adherence to manufacturer and industry guidelines. From roof deck preparation to final ridge capping, each step plays a crucial role in ensuring the roof performs optimally under a variety of weather conditions. By following the detailed instructions outlined in this guide, homeowners, contractors, and DIY enthusiasts can achieve a durable, weather-resistant roofing system that enhances both the aesthetics and functionality of a home.