Metal Roofing Over Asphalt Shingles

Initial Assessment

Deciding whether to install a metal roof over existing asphalt shingles requires careful consideration of several factors. A thorough assessment ensures the project’s success and prevents unforeseen complications. This involves evaluating the structural integrity of the existing roof, the condition of the asphalt shingles, and the overall suitability of the house for the added weight and potential changes in ventilation.

The added weight of a metal roof presents a significant consideration. Metal roofing, while durable, is heavier than asphalt shingles. This increased weight needs to be evaluated against the structural capacity of the existing roof trusses, rafters, and supporting walls. An older home, for example, may not be able to support the additional load without reinforcement or modifications. The potential need for structural reinforcement should be assessed by a qualified structural engineer before proceeding with the installation. This assessment may involve calculations based on the existing roof structure’s load-bearing capacity and the weight of the new metal roofing system, including any added underlayment. A visual inspection may also reveal signs of existing structural weaknesses such as sagging rafters or damaged sheathing.

Existing Asphalt Shingle Roof Evaluation

Evaluating the condition of the existing asphalt shingle roof is crucial. A compromised underlayment or significant shingle damage can lead to problems after the metal roof installation. The assessment should focus on several key areas. First, a thorough inspection should be conducted to identify any signs of damage or deterioration to the existing asphalt shingles, including missing or damaged shingles, curling, blistering, or excessive granule loss. Next, the condition of the underlying sheathing should be examined for rot, damage, or inadequate support. This often involves removing a few shingles in inconspicuous areas to inspect the sheathing. Finally, the condition of the underlayment should be assessed for tears, punctures, or deterioration. If significant damage is found in any of these areas, repairs or replacements should be undertaken before installing the metal roof to ensure a long-lasting and reliable roofing system. Ignoring these issues could lead to moisture penetration, resulting in damage to the new metal roof and the underlying structure.

Removal of Asphalt Shingles

Removing asphalt shingles is a crucial first step in installing a metal roof. This process requires careful attention to safety and efficient waste management to ensure a smooth and successful project. Proper technique minimizes the risk of injury and environmental impact.

Metal roofing over asphalt shingles – The removal process itself involves several key steps, each requiring specific tools and techniques. Understanding these steps will help you complete the project safely and efficiently, regardless of the size of the roof.

Step-by-Step Shingle Removal Process

The following steps Artikel a safe and effective method for removing asphalt shingles. Remember to always prioritize safety and follow local regulations regarding waste disposal.

Preparation: Begin by inspecting the roof for any loose or damaged areas. Clear the area around the house of any debris or obstacles that could cause tripping hazards. Secure the work area with caution tape and ensure proper fall protection is in place, such as a safety harness and lifeline anchored to a secure point. Inform your neighbors of the work being done.
Start at the Eaves: Begin removing shingles from the lowest row (eaves) of the roof, working your way up. This prevents shingles from falling onto lower sections and causing damage or injury.
Careful Removal: Use a pry bar or roofing shovel to carefully loosen and remove shingles. Avoid excessive force to prevent damage to the underlying sheathing. Work in sections, removing shingles in neat piles.
Nail Removal: Once the shingles are removed, carefully remove any remaining nails using a nail puller or hammer. Be mindful of the underlying sheathing to avoid damage.
Waste Disposal: Dispose of removed shingles and nails responsibly. Many municipalities have specific regulations for construction waste disposal. Consider renting a dumpster to efficiently manage waste. Recycling options may also be available.
Inspection: Once all shingles are removed, carefully inspect the roof deck for any damage. Repair or replace any damaged or rotten sheathing before proceeding with the metal roof installation.

Methods for Asphalt Shingle Removal

There are several methods for removing asphalt shingles, each with its own advantages and disadvantages. The choice depends on factors like roof size, budget, and available resources.

Manual Removal: This method involves using hand tools like pry bars and roofing shovels to remove shingles individually. It is labor-intensive but allows for careful removal and minimizes damage to the underlying sheathing. It’s best suited for smaller roofs or when preserving the underlying structure is paramount.
Mechanical Removal: This method utilizes power tools, such as shingle removers or specialized attachments for skid steers, to speed up the process. This is significantly faster but carries a higher risk of damaging the underlying sheathing if not used carefully. It’s ideal for larger roofs where efficiency is prioritized.

Tools and Materials Checklist

Having the right tools and materials readily available is essential for efficient and safe shingle removal. This checklist ensures you are well-prepared for the task.

Pry bar or roofing shovel
Hammer and nail puller
Safety harness and lifeline
Work gloves
Safety glasses
Dust mask
Dumpster or disposal bags
Tarps to protect the ground
Ladder (if necessary)

Roof Deck Inspection and Repair

A thorough inspection of the roof deck is crucial before installing a new metal roof. Ignoring underlying issues can lead to premature failure of the new roofing system, resulting in costly repairs and potential structural damage to the building. This step ensures a long-lasting and effective metal roof installation. Identifying and addressing problems such as rot, warping, and nail pops is essential for a successful project.

Roof Deck Inspection Methods

A comprehensive inspection involves a visual assessment of the entire roof deck, paying close attention to areas prone to damage, such as valleys, ridges, and around chimneys or vents. Inspectors should look for signs of rot, warping, loose or missing sheathing, and any evidence of pest infestation. Using a moisture meter can help detect hidden moisture damage within the wood sheathing. In areas with difficult access, the use of drones equipped with high-resolution cameras can provide a detailed overview of the roof deck’s condition. Furthermore, a detailed photographic record should be maintained to document the findings and aid in the repair process.

Repairing Common Roof Deck Issues

Several methods exist for repairing common roof deck problems. Rotted areas should be cut out completely, ensuring all affected wood is removed. The exposed area is then replaced with new, pressure-treated lumber, ensuring proper fastening and sealing to prevent future moisture penetration. Warping can sometimes be addressed by strategically placing additional support beams or by using shims to level the deck. Nail pops, where nails have worked their way loose, can be fixed by driving the nails back in place or replacing them with longer, stronger nails. For extensive damage, complete roof deck replacement may be necessary. This ensures a stable and secure base for the new metal roofing system.

Roof Deck Repair Materials

The choice of repair material depends on the extent of the damage and the specific needs of the project. Below is a comparison of common materials:

Material	Properties	Applications	Considerations
Pressure-Treated Lumber	Durable, resists rot and insect damage	Replacing rotted sections, adding support	Requires proper sealing to prevent leaching
Plywood (Exterior Grade)	Strong, relatively inexpensive	Replacing large areas of damaged sheathing	Susceptible to moisture damage if not properly sealed
Oriented Strand Board (OSB)	Strong, cost-effective	Replacing damaged sheathing	Can be less durable than plywood in wet climates
Composite Lumber	Rot and insect resistant, low maintenance	Repairing small areas, adding support	More expensive than traditional lumber

Metal Roofing Installation

Installing a metal roof over existing asphalt shingles requires careful planning and execution to ensure a long-lasting, weather-resistant roof. This process involves several key steps, from material selection to final fastening, all of which must be performed correctly to achieve optimal results. Proper installation techniques are crucial for preventing leaks, maximizing the lifespan of the roofing system, and maintaining the structural integrity of the building.

Metal Roofing Materials

Several types of metal roofing are suitable for installation over asphalt shingles. The choice depends on factors such as budget, aesthetic preferences, and the specific climate. Each material offers unique advantages and disadvantages that should be carefully considered.

Aluminum: Lightweight, corrosion-resistant, and relatively inexpensive, aluminum is a popular choice. However, it can dent more easily than steel.
Steel: Stronger and more durable than aluminum, steel offers excellent protection against harsh weather conditions. It’s available in various finishes, including painted and galvanized options. Galvanized steel offers superior corrosion resistance.
Copper: A premium option known for its longevity and aesthetic appeal. Copper develops a distinctive patina over time, enhancing its visual charm. However, it is significantly more expensive than aluminum or steel.
Zinc: Similar to copper in terms of longevity and corrosion resistance, zinc also develops a unique patina. It’s a more sustainable option, as it’s highly recyclable.

Installation Steps, Metal roofing over asphalt shingles

The installation process begins with preparing the roof deck, ensuring it’s clean, dry, and free of debris. The following steps Artikel the typical installation procedure:

Underlayment Installation: A layer of underlayment is installed over the existing roof deck to provide an additional layer of protection against moisture.
Flashing Installation: Proper flashing is crucial around chimneys, vents, and other penetrations to prevent water leakage. Flashing should be installed before the metal panels are applied.
Metal Panel Installation: Metal panels are typically installed starting at the lowest point of the roof and working upwards. Panels are overlapped to ensure a watertight seal.
Fastening: Self-tapping screws are commonly used to fasten the metal panels to the roof deck. These screws should be long enough to penetrate the underlayment and securely attach to the decking, but not so long as to penetrate the outer layer of the metal panel.
Ridge Cap Installation: The ridge cap is the final piece installed, covering the peak of the roof and providing a finished look.

Ventilation and Water Drainage

Proper ventilation and water drainage are critical for preventing moisture buildup and extending the lifespan of the metal roof. Adequate ventilation helps to prevent condensation and heat buildup within the attic space. Water drainage is facilitated by the slope of the roof and the proper installation of gutters and downspouts. The design should incorporate sufficient ventilation at the soffit and ridge to ensure proper airflow. For optimal drainage, it’s important to maintain the correct slope and ensure gutters are free of debris. Consider adding drip edges to help direct water away from the fascia board and prevent water damage. Regular gutter cleaning is essential for maintaining efficient water drainage.

Flashing and Sealing

Proper flashing and sealing are critical components of a long-lasting and leak-free metal roof. These measures prevent water intrusion, which can lead to significant structural damage, mold growth, and costly repairs. Neglecting this crucial step can undermine the entire investment in a new metal roof. This section details the importance of flashing, various flashing materials, and a step-by-step installation guide.

Flashing is essential for creating a watertight seal around any area where the roof plane is interrupted. This includes chimneys, vents, skylights, valleys, and the intersections of different roof sections. Without proper flashing, water can easily penetrate these vulnerable points, leading to leaks and potentially extensive damage. The selection of appropriate flashing materials is vital to ensure durability and compatibility with the metal roofing system.

Flashing Materials and Applications

Several materials are commonly used for flashing, each with its own strengths and weaknesses. The choice depends on the specific application and the overall roofing system.

Galvanized Steel: A cost-effective and durable option, often used for general flashing applications. Its zinc coating provides excellent corrosion resistance.
Aluminum: Lighter than steel and highly resistant to corrosion, making it a good choice for areas prone to moisture. It’s often preferred for its flexibility and ease of shaping.
Copper: A highly durable and aesthetically pleasing material with excellent corrosion resistance. It’s often used for high-end applications or in areas where longevity is paramount, though it’s more expensive than steel or aluminum.
Lead-coated Copper: Offers superior corrosion resistance compared to standard copper, especially beneficial in harsh environments.
Synthetic Flashing: These are rubber or polymer-based materials that offer excellent flexibility and water resistance. They are often used for smaller penetrations or as a secondary sealant.

Installing Flashing Around Roof Penetrations

The installation process for flashing varies slightly depending on the specific penetration and materials used, but the general principles remain consistent. Careful attention to detail is crucial to ensure a watertight seal.

Preparation: Clean the area around the penetration thoroughly. Remove any loose debris or old sealant. Ensure the surface is dry before starting.
Base Flashing Installation: Install the base flashing, ensuring it extends several inches up and down the penetration and overlaps the roofing material. Use appropriate fasteners for the chosen flashing material. For chimneys, the base flashing should extend several inches up the sides and be properly sealed.
Counter Flashing Installation: For penetrations like chimneys, install counter flashing, which overlaps the base flashing and is secured into the masonry. This creates a double layer of protection. This step is crucial to prevent water from traveling down behind the base flashing.
Caulk Application: Apply a high-quality sealant around the edges of the flashing to further seal any gaps and prevent water intrusion. Ensure the sealant is compatible with both the flashing material and the roofing material.
Cap Flashing Installation (if applicable): Install cap flashing to cover the top of the penetration, ensuring it overlaps the counter flashing and sheds water away from the penetration.
Inspection: Thoroughly inspect the completed flashing installation for any gaps or imperfections. Address any issues immediately to prevent future leaks.

Underlayment Considerations

Protecting your roof deck with appropriate underlayment is a crucial step in ensuring the longevity and performance of your new metal roof. Underlayment acts as a secondary barrier against moisture, providing an extra layer of defense should any water penetrate the metal roofing system. This is particularly important in areas with heavy rainfall or snowfall, or where the roof’s design might present challenges for complete water shedding. A properly installed underlayment significantly reduces the risk of costly water damage to the roof deck and the interior of your building.

Underlayment provides several key benefits beyond simple moisture protection. It acts as a buffer against wind uplift, which can be particularly damaging to metal roofing systems. It also aids in preventing the potential for damage during the installation process, protecting the roof deck from accidental scratches or punctures. Finally, a good quality underlayment will contribute to a quieter living space by helping to dampen the sound of rain and hail impacting the metal roof.

Types of Underlayment for Metal Roofing

Several types of underlayment are suitable for use beneath metal roofing, each with its own advantages and disadvantages. The choice of underlayment often depends on factors such as climate, budget, and the specific requirements of the roofing project.

Felt Underlayment: This traditional option, typically asphalt-saturated felt, is relatively inexpensive and readily available. However, it offers less protection against moisture than other types and is more susceptible to tearing. It’s generally considered a less durable option for long-term protection compared to synthetic underlayments.
Synthetic Underlayment: These are typically made from polypropylene or polyethylene and offer superior protection against moisture, wind uplift, and punctures compared to felt. They are more durable and longer-lasting, often coming with warranties that extend beyond those offered with felt underlayment. Different synthetic underlayments offer varying degrees of water resistance and UV protection. Examples include rubberized asphalt underlayments which provide greater flexibility and tear resistance.
Rubberized Asphalt Underlayment: This type combines the flexibility of synthetic underlayments with the water-resistance properties of asphalt. They are typically more expensive than standard felt but offer a good balance of cost and performance.

Underlayment Installation Process

Correct installation of underlayment is critical to maximizing its effectiveness. Improper installation can negate the benefits of using a high-quality product.

The process generally involves starting at the lowest point of the roof and working upwards, overlapping each layer according to the manufacturer’s instructions. Seams should be sealed with appropriate tape or sealant to prevent water penetration. Special attention should be paid to areas around chimneys, vents, and other penetrations where flashing is required, ensuring complete coverage and a watertight seal. The underlayment should be laid smoothly and taut to avoid wrinkles or sagging which could compromise its performance. Fasteners should be used to secure the underlayment to the roof deck, especially in windy areas. For example, using roofing nails or staples at appropriate intervals ensures the underlayment remains securely in place. The number and spacing of fasteners will vary depending on the underlayment material and local building codes.

Cost Analysis

Understanding the cost of installing a metal roof over existing asphalt shingles is crucial for budgeting and planning. Several factors contribute to the final price, making it essential to obtain detailed quotes from reputable contractors. This analysis breaks down the typical expenses and explores the long-term cost-effectiveness of this roofing upgrade.

Typical Cost Breakdown

The total cost of installing a metal roof over asphalt shingles is comprised of several key components. Labor costs, material expenses (including the metal roofing panels, underlayment, fasteners, and flashing), and permit fees all contribute to the overall project expense. Additional costs may include debris removal, roof deck repairs, and the disposal of the old asphalt shingles. The price per square foot can vary significantly depending on the chosen metal roofing material (e.g., steel, aluminum, copper), its gauge (thickness), and the complexity of the roof’s design. For example, a simple gable roof will generally cost less than a complex hip roof with many valleys and dormers.

Factors Influencing Overall Cost

Several factors significantly influence the overall project cost. The size and complexity of the roof are primary determinants. Larger, more intricate roofs naturally require more materials and labor, driving up the cost. The chosen metal roofing material also plays a crucial role; copper, for instance, is considerably more expensive than steel. The location of the project can affect labor costs, as well as the availability and price of materials. Regional variations in labor rates and material costs should be anticipated. Finally, the need for extensive roof deck repairs or the presence of unexpected issues during the shingle removal process can add to the overall expense. For example, discovering significant rot or damage to the sheathing may necessitate additional time and materials for repairs.

Long-Term Cost Savings Comparison

The higher initial investment in a metal roof is often offset by its significantly longer lifespan and lower maintenance requirements compared to asphalt shingles.

Feature	Metal Roofing	Asphalt Shingles	Notes
Initial Cost	Higher	Lower	Significant variation based on metal type and roof complexity.
Lifespan	50-75 years	15-30 years	Metal roofs significantly outlast asphalt shingles.
Maintenance	Low	Moderate to High	Metal roofs require minimal maintenance, while asphalt shingles may need repairs and replacements.
Insurance Costs	Potentially Lower	Potentially Higher	Some insurance companies offer discounts for fire-resistant metal roofing.
Resale Value	Increases	Decreases	A durable metal roof can significantly enhance a home’s resale value.

Permits and Regulations: Metal Roofing Over Asphalt Shingles

Replacing your asphalt shingle roof with a metal roof is a significant home improvement project, and navigating the local regulations is a crucial step to ensure a smooth and legal process. Understanding and complying with building codes and obtaining the necessary permits protects you from potential fines, delays, and even the need to undo completed work. This section Artikels the typical process and considerations.

Before starting any work, it is essential to contact your local building department. They are the primary source of information regarding specific requirements for your area. Requirements can vary significantly depending on factors such as your location, the type of metal roofing material chosen, the size and complexity of your roof, and even the age of your home.

Obtaining Necessary Permits

The permit application process generally involves submitting detailed plans of your proposed roof replacement, including specifications of the metal roofing materials, underlayment, and any structural modifications. You’ll likely need to provide documentation demonstrating that the chosen materials meet local building codes regarding fire resistance, wind resistance, and other relevant safety standards. The plans should clearly show the dimensions of your roof, the type of fastening system to be used, and details of any necessary flashing or penetrations. The building department will review your application and plans, and if everything is in order, they will issue a permit. This permit is legal proof that your project complies with local regulations and allows you to proceed with the installation. Failure to obtain a permit before starting work can result in significant penalties.

Local Building Codes and Regulations

Local building codes often dictate specific requirements for roofing materials, including minimum wind load resistance, fire ratings, and installation methods. For example, some areas may require specific types of underlayment or fasteners to ensure the longevity and safety of the roof. Other regulations may pertain to the color or reflectivity of the roofing material, especially in areas with strict aesthetic guidelines or those focused on energy efficiency. Furthermore, some jurisdictions might have specific requirements for the disposal of old roofing materials, including the proper handling and removal of asbestos if present in older asphalt shingles. It is vital to check your local building codes thoroughly before beginning the project. These codes can usually be found online through your local government’s website or at the building department’s office.

Importance of Compliance

Compliance with all relevant building codes and regulations is paramount. Non-compliance can lead to several serious consequences. This includes the potential for fines, stop-work orders, and even the requirement to remove the new roof and redo the installation to meet the standards. More importantly, failing to meet building codes can compromise the safety and structural integrity of your home, potentially leading to significant damage or even injury in severe weather conditions. By ensuring full compliance, you protect your investment and ensure the long-term safety and value of your property.

Visual Representation

Visual aids are crucial for understanding the complex layering of a roof system and the intricacies of installation. Detailed illustrations help clarify the process, ensuring proper execution and preventing potential issues. The following sections provide descriptive representations of key aspects of metal roofing over asphalt shingles.

Roof Layers with Metal Roofing Over Asphalt Shingles

Imagine a cross-section of the roof. The lowest layer is the roof deck, typically plywood or OSB, providing the structural base. Above this is the existing asphalt shingle layer, showing its overlapping pattern. Next, a layer of underlayment—likely a synthetic material like felt or rubber—is added for extra waterproofing. Finally, the metal roofing panels are installed, overlapping to create a weathertight seal. Each layer is clearly labeled in the illustration, highlighting the order and function of each component. The illustration emphasizes the complete coverage of the asphalt shingles by the underlayment and metal roofing, ensuring a robust and durable roof system.

Flashing Installation Around a Chimney

This illustration depicts a chimney penetrating the roof, showcasing the critical flashing system. The base flashing, a continuous piece of metal, is installed under the shingles and up against the chimney, creating a watertight seal at the base. The step flashing, individual pieces of metal, are installed in overlapping layers, each shingle course, up the chimney. The counter flashing, a metal piece embedded into the mortar of the chimney, overlaps the step flashing, preventing water from seeping behind it. Finally, cap flashing covers the top of the chimney, diverting water away from the intersection. The illustration uses different colors and labels to clearly distinguish each component and their respective positions. The importance of proper overlapping and sealing between each flashing piece is clearly highlighted.

Metal Roofing Panels and Fastening Methods

This visual representation shows three common types of metal roofing panels: standing seam, corrugated, and ribbed. Each panel type has a unique profile and fastening method. Standing seam panels are characterized by a raised seam that creates a channel for water runoff, and they are typically fastened using concealed clips, creating a clean and seamless look. Corrugated panels have a wavy profile and are usually fastened with screws through the panel crests. Ribbed panels, featuring parallel raised ribs, are often secured with screws, though hidden fastening systems are also available. The illustration shows the panels themselves, highlighting their distinct profiles. It also clearly depicts the fastening methods, including the location of screws or clips, emphasizing the importance of proper spacing and sealing to prevent leaks. The illustration clearly shows how the panel’s profile affects the installation method and overall appearance.

Questions and Answers

Can I install metal roofing over damaged asphalt shingles?

No. Damaged shingles must be removed before installing metal roofing. The underlying roof deck needs to be inspected and repaired as necessary for a secure and long-lasting installation.

How long does it take to install metal roofing over asphalt shingles?

The installation time varies depending on the roof size and complexity, but it generally takes longer than a new asphalt shingle installation. Expect several days to a couple of weeks for a typical-sized house.

What is the warranty on metal roofing?

Metal roofing warranties vary by manufacturer and type of metal. They typically range from 20 to 50 years, often covering material defects and sometimes workmanship.

Is metal roofing noisy during rain?

While some noise is possible, modern metal roofing systems are designed to minimize rain noise. The level of noise can also depend on the type of underlayment and insulation used.