Metal Roofing Over Asphalt Shingles

Cost Comparison

Choosing between installing a metal roof over existing asphalt shingles or opting for a complete tear-off significantly impacts the overall cost. This decision requires careful consideration of various factors, including material expenses, labor costs, permitting fees, and waste disposal. Understanding these cost differences is crucial for making an informed and financially responsible choice.

Cost Breakdown: Metal Roofing Installation

The following table provides a comparative cost analysis for installing a metal roof over existing asphalt shingles versus a complete tear-off and new installation. These figures are estimates and can vary significantly based on location, roof size and complexity, material choices, and contractor rates. It’s crucial to obtain multiple quotes from reputable contractors in your area for accurate pricing.

Scenario	Material Costs	Labor Costs	Permits	Disposal Fees
Over Existing Shingles	$8,000 – $15,000 (depending on metal type and roof size)	$4,000 – $8,000 (reduced labor due to less demolition)	$200 – $500	$100 – $300 (minimal waste)
Complete Tear-Off	$8,000 – $15,000 (same as above)	$8,000 – $15,000 (increased labor due to tear-off and disposal)	$200 – $500	$500 – $1,500 (significant waste from old shingles)

Long-Term Cost Savings of Metal Roofing

Metal roofing offers substantial long-term cost advantages compared to asphalt shingles. These savings stem from its superior durability, longevity, and low maintenance requirements.

Metal roofing over asphalt shingles – The following points illustrate the significant long-term cost benefits of investing in a metal roof:

Extended Lifespan: Metal roofs typically last 50 years or more, significantly longer than asphalt shingles (15-30 years). This reduces the frequency of costly replacements, resulting in substantial long-term savings.
Reduced Maintenance: Metal roofs require minimal maintenance. Unlike asphalt shingles, they are resistant to rot, insect infestation, and algae growth, eliminating the need for regular repairs or replacements of damaged sections.
Lower Insurance Premiums: Some insurance companies offer reduced premiums for homes with metal roofs due to their fire-resistant properties and increased longevity. This can lead to significant savings over the life of the roof.
Increased Home Value: A metal roof is considered a high-value improvement, potentially increasing your home’s resale value. This is a considerable financial benefit when you eventually sell your property.
Energy Efficiency: Certain metal roofing types can enhance energy efficiency by reflecting sunlight and reducing cooling costs. This leads to long-term savings on your energy bills.

Structural Considerations

Replacing an asphalt shingle roof with a metal roof involves a significant change in weight distribution on your home’s structure. Asphalt shingles are relatively lightweight, while metal roofing, even in its lighter forms, adds considerably more weight. It’s crucial to assess the structural integrity of your home to ensure it can safely support this increased load. Neglecting this step could lead to structural damage or even collapse.

The added weight of a metal roof necessitates a careful evaluation of your home’s existing framing, rafters, and trusses. This is particularly important for older homes or those with known structural issues. A thorough inspection by a qualified structural engineer is highly recommended before beginning any metal roofing installation. This professional assessment will determine if reinforcements are needed and specify the necessary upgrades to support the increased weight. Reinforcements may involve adding additional structural supports, such as stronger rafters or trusses, or potentially reinforcing the walls and foundation. The engineer’s report will provide a detailed plan for any required modifications, ensuring the long-term safety and stability of your home.

Roof Deck Assessment and Preparation

Before installing a metal roof over existing asphalt shingles, the existing roof deck must be thoroughly inspected for damage, rot, or any other issues that could compromise the integrity of the new roof. This process typically involves removing sections of the shingles to assess the underlying plywood or OSB sheathing. Any damaged or deteriorated sections of the decking will need to be repaired or replaced before the metal roofing can be installed. This ensures a stable and even surface for the new roof and prevents potential problems down the line.

Potential Challenges in Preparing the Existing Roof

The process of preparing an existing asphalt shingle roof for metal roofing can present several challenges. One common challenge is dealing with aged or damaged asphalt shingles. Removing these shingles carefully without damaging the underlying deck requires skill and experience. Furthermore, the presence of existing roof penetrations, such as chimneys, vents, and skylights, necessitates careful planning and execution to ensure proper sealing and flashing around these elements. Improper preparation in these areas can lead to leaks and water damage. Another significant challenge can be unexpected discoveries during the removal of the asphalt shingles. For instance, the discovery of extensive rot or damage to the underlying decking might require significant repairs or even a complete roof deck replacement, adding unforeseen time and expense to the project. Finally, the removal of the asphalt shingles themselves can generate substantial waste, requiring careful planning for disposal.

Installation Methods

Installing a metal roof over existing asphalt shingles requires careful planning and execution to ensure a long-lasting and leak-proof result. This process involves several key steps, from preparation to final securing, all of which are crucial for a successful installation. Understanding these steps will help homeowners and contractors alike achieve optimal results.

Step-by-Step Metal Roof Installation Over Asphalt Shingles

The following steps provide a comprehensive guide for installing a metal roof over existing asphalt shingles. Careful adherence to these steps will minimize risks and ensure a quality installation.

Preparation: Begin by thoroughly inspecting the existing roof for any damaged or loose shingles. Repair or replace any damaged areas. Ensure all flashing around chimneys, vents, and valleys is in good condition. This step is crucial for preventing future leaks. Imagine inspecting the roof like a doctor performing a thorough check-up, identifying and addressing any potential problems before starting the procedure.
Underlayment Installation: Install a new layer of underlayment over the existing shingles. This provides an additional layer of protection against leaks and will help to create a smoother surface for the metal roofing panels. This extra layer acts like a safety net, providing an additional barrier against moisture intrusion. Picture a waterproof blanket laid over the existing roof.
Fastener Placement: Metal roofing panels are typically fastened using screws. Pre-drill pilot holes to prevent the metal from cracking. Use screws specifically designed for metal roofing, ensuring they are long enough to penetrate the underlayment and existing roof deck. This precise fastening is key to the structural integrity of the new roof. Imagine carefully sewing together pieces of fabric, each stitch strategically placed for strength.
Panel Installation: Begin installing the metal panels from the bottom edge of the roof, working your way up. Overlap each panel according to the manufacturer’s instructions. Ensure proper alignment and secure each panel with screws. This step requires patience and precision, ensuring each panel is perfectly aligned and securely fastened. This is akin to meticulously laying bricks to build a sturdy wall.
Flashing Installation: Install flashing around all penetrations, such as chimneys, vents, and skylights. This prevents water from entering the roof system. Careful flashing installation is critical to a waterproof roof. Imagine carefully sealing the seams of a waterproof suit to ensure complete protection from the elements.
Ridge Cap Installation: Install the ridge cap to cover the top seam of the metal roofing panels. This protects the seam from the elements and enhances the roof’s aesthetic appeal. The ridge cap acts as a crown, completing the roof’s protective layer and adding a final touch of elegance.

Metal Roofing Panel Types

Several metal roofing panel types are suitable for installation over asphalt shingles. The choice depends on factors such as weight, cost, and ease of installation. The following table compares some common types.

Panel Type	Weight	Ease of Installation	Description
Standing Seam	Moderate to Heavy	Moderate	Known for its clean, sleek appearance and excellent durability. Requires specialized tools and experience for proper installation. The panels interlock to create a virtually seamless, watertight system. Imagine a series of interlocking metal tiles forming a strong, elegant roof.
Ribbed Panel	Light to Moderate	Easy	Offers a more textured appearance. Generally easier and faster to install than standing seam panels. The ribs add structural strength and aesthetic appeal. Think of corrugated metal sheets, strong and relatively simple to work with.
Corrugated Panel	Light	Easy	A cost-effective option with a rustic look. Installation is straightforward, making it a popular choice for DIY projects. These panels resemble wavy metal sheets, simple and efficient.

Potential Problems and Solutions

Installing a metal roof over existing asphalt shingles presents unique challenges. While cost-effective and offering longevity, this approach necessitates careful planning and execution to avoid potential problems. Ignoring these potential issues can lead to costly repairs and compromise the integrity of the new roof system. This section details common problems encountered and offers practical solutions for successful installation.

Leaks

Leaks are a major concern when installing a metal roof over asphalt shingles. The existing shingle layer, if not properly prepared, can create pathways for water to penetrate the new metal roofing. Furthermore, improper flashing around chimneys, vents, and other penetrations can also lead to leaks.

Thorough Shingle Inspection and Removal of Damaged Sections: Before installing the metal roofing, carefully inspect the existing asphalt shingles for damage. Remove any cracked, curled, or missing shingles. Repairing these areas before installing the metal roof prevents water from seeping through gaps. This is crucial for long-term leak prevention.
Proper Flashing Installation: Ensure that all flashing around chimneys, vents, and other roof penetrations is properly installed and sealed. Use high-quality flashing materials, such as aluminum or copper, and seal all seams with a durable sealant compatible with both the metal roofing and flashing materials. A well-sealed flashing system prevents water from entering the roof at these vulnerable points.
Careful Seam Sealing: Metal roofing panels must be properly overlapped and sealed at the seams. Use high-quality sealant designed for metal roofing to ensure a watertight seal. This is particularly important in areas prone to high winds and heavy rainfall. The sealant should be applied according to the manufacturer’s instructions.

Wind Uplift

Metal roofing, while durable, can be susceptible to wind uplift, especially in areas with high winds. The wind can get underneath the metal panels and lift them off the roof deck, causing damage to the roofing system and potentially leading to leaks.

Secure Fastening: Use the appropriate fasteners for the metal roofing material and the roof deck. Overlapping panels and using additional clips or straps will provide extra security against wind uplift. Fasteners should be spaced according to the manufacturer’s recommendations and driven straight to avoid creating weak points.
Proper Underlayment: Installing a high-quality underlayment beneath the metal roofing can provide an additional layer of protection against wind uplift. This will help to create a more secure barrier against wind penetration. Choose an underlayment designed for use with metal roofing systems.
Wind Bracing: In high-wind areas, consider adding wind bracing to the roof structure to increase its resistance to wind uplift. This may involve adding additional structural supports or strengthening existing ones. A structural engineer can assess the need for wind bracing and recommend appropriate solutions.

Inadequate Ventilation

Inadequate ventilation can lead to moisture buildup beneath the metal roofing, which can cause condensation, rust, and premature failure of the roofing system. This is especially true when installing a metal roof over existing asphalt shingles, as the existing layer can trap heat and moisture.

Ridge Vents and Soffit Vents: Ensure adequate ventilation by installing ridge vents and soffit vents. These vents allow for proper airflow, preventing moisture buildup and maintaining a healthy attic environment. Proper venting helps to regulate attic temperature and humidity.
Continuous Ventilation: Consider using continuous ventilation systems, which provide a more even distribution of airflow across the attic space. This ensures that all areas of the attic are properly ventilated. This approach is particularly beneficial for larger roofs.
Inspection and Cleaning of Vents: Regularly inspect and clean vents to ensure they are not blocked by debris or insulation. Blocked vents can significantly reduce ventilation effectiveness. This simple maintenance task prevents the accumulation of moisture and extends the lifespan of the roof system.

Insulation and Ventilation

Proper insulation and ventilation are crucial when installing a metal roof over existing asphalt shingles. These elements significantly impact the energy efficiency, longevity, and overall performance of your roofing system. Neglecting them can lead to issues such as moisture buildup, thermal bridging, ice damming, and reduced lifespan of both the roof and the underlying structure. A well-designed system prevents these problems, creating a comfortable and energy-efficient home.

Adequate insulation and ventilation work in tandem to regulate the temperature and moisture levels within the attic space. Insulation prevents heat transfer, keeping your home cool in summer and warm in winter. Ventilation, on the other hand, allows for the movement of air, removing excess moisture and preventing the buildup of heat. This combined approach is particularly important when installing a metal roof, as metal is a highly conductive material.

Attic Ventilation Strategies

Effective attic ventilation requires a balanced intake and exhaust system. Sufficient intake vents, often located in the soffits, allow cool, dry outside air to enter the attic. Exhaust vents, typically located at the ridge or gable ends, expel hot, moist air. This creates a continuous airflow, preventing moisture accumulation. The size and placement of these vents should be calculated based on the attic’s square footage, following building codes and manufacturer recommendations. For example, a 1500 square foot attic might require a combined intake and exhaust vent area of at least 1/150th of the attic floor area, or approximately 10 square feet. This ensures adequate airflow to manage moisture and prevent overheating. A common issue is insufficient exhaust ventilation, which can lead to moisture condensation and subsequent damage to insulation and roofing materials.

Underlayment and Vapor Barriers

A properly installed underlayment plays a critical role in preventing moisture intrusion. A breathable underlayment allows moisture vapor to escape from the attic while preventing liquid water from penetrating. This is particularly important in climates with high humidity or significant snowfall. The underlayment should be installed according to manufacturer’s instructions, ensuring proper overlap and sealing at seams. A vapor barrier, located beneath the insulation, can further prevent moisture migration from the living space into the attic. The choice of vapor barrier depends on the climate and building materials. In humid climates, a highly effective vapor barrier is essential. Conversely, in drier climates, a less restrictive barrier might be sufficient. Improper installation of either the underlayment or vapor barrier can compromise the overall effectiveness of the ventilation system.

Ventilation System Diagram Description

Imagine a cross-section of your attic. At the lower edge, along the soffits, you would see evenly spaced intake vents. These vents allow the entry of outside air. This cool, dry air then flows across the attic space, moving upwards and across the insulation. At the peak of the roof, ridge vents (or gable vents if ridge vents are not feasible) act as exhaust vents. These vents release the now warm, moist air that has absorbed moisture from within the attic. The continuous airflow created by this intake-exhaust system effectively removes moisture and heat, protecting the roof and the structure beneath. The insulation layer sits between the underlayment and the attic space, further preventing heat transfer and creating a more energy-efficient environment. A vapor barrier (if used) would be situated beneath the insulation layer to prevent moisture from entering the attic from the living space below. This integrated system ensures a dry, well-ventilated attic, protecting the roof and extending its lifespan.

Warranty and Permits

Installing a metal roof over existing asphalt shingles presents unique considerations regarding warranties and necessary permits. Understanding these aspects is crucial for a smooth and legally compliant project. Failure to address these issues can lead to disputes and potential legal ramifications.

The installation of a new metal roof over existing asphalt shingles will likely void any remaining warranty on the underlying asphalt shingles. Most asphalt shingle manufacturers’ warranties are contingent upon proper installation and adherence to specific guidelines, which are typically invalidated when an additional roofing layer is added. This is because the added weight and potential for moisture trapping between the layers can negatively impact the performance and lifespan of the original shingles. The manufacturer might argue that the added layer compromised the integrity of their product, releasing them from warranty obligations. Checking your specific shingle warranty documentation is essential. It’s important to note that the warranty on the *new* metal roof will typically remain unaffected by the presence of the underlying asphalt shingles, provided the installation is done correctly.

Impact on Existing Roof Warranty

The addition of a metal roof over existing asphalt shingles almost always voids the remaining warranty on the underlying asphalt shingles. This is because the extra weight and potential for moisture buildup between the layers can damage the original shingles, reducing their lifespan and potentially leading to premature failure. This is a common clause in most manufacturer warranties. The new metal roofing system, however, will typically have its own independent warranty, provided the installation meets the manufacturer’s specifications. This independent warranty is unaffected by the underlying asphalt shingles. For example, a 50-year warranty on a metal roof will still apply, even with asphalt shingles underneath, provided the installation is correct and no damage is caused to the metal roof during the installation process.

Permitting Process for Metal Roof Over Shingles, Metal roofing over asphalt shingles

The permitting process for installing a metal roof over existing asphalt shingles varies by location. It typically involves submitting an application to your local building department. This application usually requires detailed plans, specifications of the materials to be used (including the metal roofing system and any underlayment), and the contractor’s license information. Some jurisdictions might require a site inspection before issuing a permit, and others may require inspections during and after the installation process to ensure compliance with building codes and safety regulations. For example, in some areas, you might need to demonstrate that the added weight of the metal roof will not exceed the structural capacity of the existing building. Failure to obtain the necessary permits before starting the project can result in fines and even legal action. The required documentation often includes proof of insurance for the contractor and detailed specifications of the entire roofing system.

Material Selection

Choosing the right metal roofing material for your project is crucial, impacting both the longevity and aesthetic appeal of your home. This decision involves careful consideration of several factors, including durability, cost, and the desired visual effect. The following comparison of common metal roofing materials will aid in making an informed choice.

Metal Roofing Material Comparison

The selection of metal roofing material depends heavily on budget, desired lifespan, and aesthetic preferences. Steel, aluminum, and copper each offer unique properties. The table below summarizes key differences.

Material	Durability & Lifespan	Cost	Aesthetics
Steel	Highly durable; lifespan typically ranges from 50 to 75 years, sometimes longer depending on coating and environmental conditions. Prone to rust if not properly coated.	Generally the most affordable option among the three.	Available in a wide range of colors and finishes, offering versatility in design. Can mimic the appearance of other materials.
Aluminum	Excellent durability and corrosion resistance; lifespan can exceed 50 years. Lightweight, making installation easier.	More expensive than steel, but less costly than copper.	Often available in a limited range of colors compared to steel, typically in muted tones.
Copper	Exceptional durability and longevity; lifespan can exceed 100 years. Naturally resistant to corrosion and develops a distinctive patina over time.	Significantly more expensive than steel and aluminum.	Unique aesthetic appeal due to its natural color and aging process. The patina develops a rich, greenish-brown hue over time.

Metal Roofing Material Characteristics

Each metal type possesses distinct characteristics influencing its suitability for a particular application.

Steel roofing, while cost-effective, requires a high-quality coating to prevent rust. Regular inspections are recommended to identify and address any signs of damage or corrosion promptly. Aluminum, being lightweight and corrosion-resistant, requires minimal maintenance. However, it can dent more easily than steel. Copper, with its exceptional longevity and self-healing properties, demands little maintenance beyond occasional cleaning. Its inherent resistance to corrosion makes it a highly desirable, albeit expensive, option. The development of the patina on copper is a natural process and adds to its unique aesthetic value. However, some homeowners may prefer to use a protective coating to maintain a more uniform color.

Underlayment Considerations

Installing metal roofing over existing asphalt shingles requires careful consideration of underlayment. This crucial layer provides an additional barrier against moisture penetration, protecting the roof deck and ensuring the longevity of the new metal roof. Choosing the right underlayment and installing it correctly is vital for a successful and leak-free roofing system.

The selection of appropriate underlayment depends on several factors, including climate, the condition of the existing asphalt shingles, and the type of metal roofing being installed. A common choice is a synthetic underlayment, offering superior water resistance and tear strength compared to traditional felt underlayment. These synthetic options are often more durable and less susceptible to damage during installation. In areas with high rainfall or snowfall, a higher-performing underlayment with enhanced water resistance might be necessary. The existing shingle condition should also be assessed; if the shingles are brittle or damaged, a more robust underlayment might be needed to prevent debris from puncturing the new underlayment.

Underlayment Material Selection

Synthetic underlayments are generally preferred over traditional asphalt-saturated felt due to their superior strength and water resistance. These synthetic materials, often made from polypropylene or polyethylene, offer better tear resistance, preventing damage during the installation process. They also provide enhanced UV resistance, protecting the underlayment from degradation before the metal roofing is installed. The choice between different synthetic underlayments often comes down to specific performance characteristics, such as water resistance ratings and tensile strength. For example, some high-performance underlayments offer enhanced protection against wind-driven rain.

Underlayment Installation Process

Proper installation of the underlayment is critical to its effectiveness. The process typically begins with a thorough cleaning of the existing roof to remove loose debris and any damaged shingles. The underlayment rolls are then unrolled, starting at the lowest point of the roof and working upwards. Overlapping is crucial, ensuring that each subsequent layer overlaps the previous one by at least six inches to prevent water penetration. This overlap should be even and consistent across the entire roof. The underlayment is typically fastened to the roof deck using staples or roofing nails, following the manufacturer’s recommended spacing.

Sealing Underlayment Seams and Flashing

Seams between underlayment rolls must be sealed to prevent water from seeping through. A high-quality roofing sealant, specifically designed for use with the chosen underlayment, should be applied to all overlaps. This ensures a waterproof seal and helps to prevent future leaks. Flashing around chimneys, vents, and other roof penetrations is also essential. The underlayment should be carefully cut and installed around these features, creating a watertight seal to prevent water from entering the roof system. Proper flashing installation is crucial for the overall performance of the roofing system and should be done with great care. Failure to adequately seal seams and properly flash penetrations is a common cause of leaks in metal roofing systems.

Snow Load and Wind Resistance

Metal roofing offers significant advantages over asphalt shingles in terms of snow load and wind resistance. Its superior strength and lighter weight, when properly installed, contribute to a more resilient roofing system capable of withstanding extreme weather conditions. This section will detail the performance differences and highlight crucial design considerations for ensuring structural integrity in high-snow and high-wind areas.

Metal roofs, due to their smooth, non-porous surface, allow snow to slide off more easily than asphalt shingles. This reduces the accumulation of heavy snow loads on the roof, minimizing the stress on the underlying structure. Furthermore, the high tensile strength of metal panels provides superior resistance to wind uplift, preventing damage from strong gusts. Asphalt shingles, being more flexible and prone to damage from wind, are significantly more vulnerable in such conditions. The difference in performance becomes particularly critical in regions experiencing frequent heavy snowfalls or high winds.

Metal Roof Snow Load Capacity

The snow load capacity of a metal roof depends on several factors including the type of metal (steel, aluminum, copper), panel profile, gauge (thickness), and the design of the supporting structure. Properly engineered metal roofing systems can significantly exceed the snow load capacity of asphalt shingle roofs. For instance, a properly designed and installed standing seam metal roof can handle snow loads exceeding 100 pounds per square foot, whereas asphalt shingles typically have a much lower capacity, often requiring additional structural reinforcement in high-snow areas. This increased capacity translates to greater safety and reduced risk of roof collapse during heavy snowfalls. Engineers use standardized snow load maps and building codes to determine the appropriate design specifications for a given location. These calculations consider factors such as geographic location, elevation, and historical snowfall data.

Metal Roof Wind Resistance

The wind resistance of a metal roof is largely determined by the panel design, fastening method, and the overall structural integrity of the roof system. Standing seam metal roofs, with their interlocking panels and secure fastening, demonstrate exceptional wind resistance, often exceeding 150 mph. The smooth surface minimizes wind friction, further enhancing its ability to withstand strong gusts. In contrast, asphalt shingles are more susceptible to wind damage, especially during high winds or hailstorms, due to their vulnerability to lifting and tearing. Proper installation, including adequate fastening and attention to details like flashings and sealing, is critical to maximizing the wind resistance of any metal roof system. Building codes specify minimum wind load requirements, and the roofing system must be designed to meet or exceed these requirements.

Ensuring Structural Integrity for High Snow Loads and Winds

To ensure the structural integrity of a roof designed to withstand high snow loads and strong winds, several key considerations are crucial. These include:

Proper Roof Design: The roof’s structural design, including the rafters, trusses, and sheathing, must be adequately engineered to support the anticipated snow and wind loads. This requires professional engineering calculations based on local building codes and specific site conditions.
Appropriate Material Selection: Selecting metal roofing panels with sufficient gauge and strength is essential. The panel profile and fastening system should also be chosen to maximize wind resistance and minimize snow accumulation.
Secure Fastening: Proper fastening of the metal panels to the roof deck is critical. Sufficient fasteners should be used, and they should be installed according to the manufacturer’s specifications to ensure a secure connection that can withstand high winds.
Reinforced Structural Members: In areas with high snow loads, reinforcing the roof’s structural members, such as rafters or trusses, may be necessary to increase their load-bearing capacity. This can involve adding additional supports or using larger-dimension lumber.
Proper Installation: Meticulous attention to detail during installation is crucial. This includes proper flashing around chimneys, vents, and other penetrations to prevent water intrusion and maintain structural integrity.

Ignoring these critical aspects can lead to potential structural failures, resulting in significant damage and safety hazards. A qualified roofing professional should be consulted to ensure that the roof is properly designed and installed to meet or exceed the required snow load and wind resistance standards for the specific location.

Environmental Impact

Choosing between metal roofing and asphalt shingles involves considering not only cost and durability but also environmental impact. Both materials have environmental footprints stemming from manufacturing, transportation, and eventual disposal. A comprehensive comparison helps homeowners make informed decisions aligned with sustainability goals.

The environmental impact of metal roofing and asphalt shingles differs significantly across their lifecycle stages. Manufacturing processes, material longevity, and end-of-life management all contribute to their overall environmental footprint. Understanding these differences is crucial for responsible building practices.

Comparison of Environmental Impacts

The following bullet points compare the environmental impacts of metal roofing and asphalt shingles:

Manufacturing: Metal roofing generally requires less energy to produce than asphalt shingles, due to the readily available and recyclable nature of the base metals. Asphalt shingle production, however, involves significant energy consumption and the use of petroleum-based materials, contributing to greenhouse gas emissions.
Lifespan: Metal roofs typically boast a much longer lifespan (50-75 years or more) compared to asphalt shingles (15-30 years). This longer lifespan reduces the frequency of roof replacements, minimizing the environmental impact associated with material extraction, manufacturing, transportation, and disposal.
Recyclability: Metal roofing is highly recyclable, with a significant portion of the material being reclaimed and reused in new products. Asphalt shingles, while sometimes recycled, often end up in landfills, contributing to waste accumulation and environmental concerns. Recycling rates vary significantly by region and infrastructure availability.
Transportation: Metal roofing components, while heavier, are often manufactured regionally, potentially reducing transportation emissions compared to asphalt shingles, which may be shipped over longer distances due to centralized production facilities.
Embodied Carbon: While the exact embodied carbon (the total greenhouse gas emissions associated with a product’s lifecycle) varies based on specific materials and manufacturing processes, studies generally show that metal roofing has a lower embodied carbon footprint than asphalt shingles over their lifespan.

Proper Disposal of Asphalt Shingles

Proper disposal of old asphalt shingles is vital for environmental sustainability. Improper disposal leads to landfill overcrowding and potential environmental contamination from leaching of harmful substances. Sustainable disposal practices include:

Recycling: Many regions offer asphalt shingle recycling programs. These programs grind the shingles into aggregate for use in road construction or other applications, diverting waste from landfills and creating a valuable secondary product. Check with your local waste management authority to see if such a program is available in your area.
Landfill Disposal (with mitigation): If recycling isn’t an option, proper landfill disposal is crucial. This involves following local regulations and ensuring the shingles are disposed of in designated areas to minimize environmental impact. Some landfills employ methods to capture and treat leachate (liquid that percolates through the waste) to prevent ground water contamination.
Avoiding illegal dumping: Illegal dumping of asphalt shingles contaminates natural environments, harming ecosystems and wildlife. Always dispose of waste responsibly through authorized channels.

Top FAQs: Metal Roofing Over Asphalt Shingles

Can I install a metal roof over damaged asphalt shingles?

No. Damaged shingles must be repaired or replaced before installing a metal roof to prevent leaks and ensure proper adhesion of the underlayment.

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

The installation time varies depending on the roof size and complexity, but it generally takes less time than a complete tear-off and new roof installation.

Will installing a metal roof over asphalt shingles void my homeowner’s insurance?

It may or may not, depending on your policy and insurance provider. Contact your insurance company to confirm coverage before starting the project.

What is the lifespan of a metal roof installed over asphalt shingles?

The lifespan depends on the type of metal used, but metal roofs generally last much longer than asphalt shingles, often 50 years or more.