Metal Roofing Over Asphalt Shingles: A Comprehensive Guide
Considering a new roof? Metal roofing is gaining popularity for its durability, longevity, and energy efficiency. But what if you already have an asphalt shingle roof? Can you install metal roofing over asphalt shingles? The answer is often yes, but it’s a decision that requires careful consideration. This comprehensive guide will walk you through the pros and cons, preparation steps, cost factors, and everything else you need to know before deciding whether to install a metal roof over your existing asphalt shingles.
The Allure of Metal Roofing
Before diving into the specifics of installing metal over asphalt, let’s understand why metal roofing is such an appealing option. Metal roofs offer a range of advantages that make them a worthwhile investment for many homeowners.
Durability and Longevity
One of the primary reasons homeowners choose metal roofing is its exceptional durability. Unlike asphalt shingles, which can deteriorate quickly under harsh weather conditions, metal roofs are built to last. They can withstand strong winds, heavy snow, hail, and even fire. A properly installed metal roof can last 50 years or more, significantly longer than the 15-20 year lifespan of a typical asphalt shingle roof.
Energy Efficiency
Metal roofs are highly reflective, meaning they reflect a significant amount of sunlight away from your home. This reduces the amount of heat absorbed by your roof, keeping your home cooler in the summer and lowering your energy bills. Some metal roofs also incorporate specialized coatings that further enhance their reflectivity.
Aesthetic Appeal
Metal roofing is available in a wide variety of styles, colors, and finishes. Whether you prefer the traditional look of shingles, the sleek lines of standing seam, or the rustic charm of metal tile, there’s a metal roofing option to suit your taste. Metal roofs can also enhance the curb appeal of your home, potentially increasing its value.
Environmental Benefits
Metal roofing is an environmentally friendly choice. Many metal roofs are made from recycled materials, and at the end of their lifespan, they can be recycled again. This reduces waste and conserves resources. Additionally, the energy efficiency of metal roofs contributes to lower greenhouse gas emissions.
Can You Install Metal Roofing Over Asphalt Shingles?
The question on many homeowners’ minds is: can you install metal roofing directly over existing asphalt shingles? In many cases, the answer is yes. However, it’s not always the best option, and there are several factors to consider.
Advantages of Installing Metal Over Asphalt
Installing metal roofing over asphalt shingles offers several potential benefits:
Cost Savings: One of the most significant advantages is the potential cost savings. Removing an existing asphalt shingle roof can be a labor-intensive and expensive process. By installing metal roofing directly over the shingles, you can avoid these removal costs.
Reduced Landfill Waste: Tearing off an old roof generates a significant amount of waste that ends up in landfills. Installing metal over asphalt eliminates this waste, making it a more environmentally responsible option.
Additional Insulation: The existing asphalt shingles can provide an extra layer of insulation, potentially improving your home’s energy efficiency.
Simplified Installation: In some cases, installing metal over asphalt can be a simpler and faster process than tearing off the old roof and starting from scratch.
Disadvantages of Installing Metal Over Asphalt
While installing metal over asphalt offers several benefits, there are also some potential drawbacks to consider:
Hidden Problems: Covering up existing asphalt shingles can hide underlying problems, such as rot, mold, or water damage. These problems could worsen over time and eventually compromise the integrity of your new metal roof.
Reduced Lifespan: If the existing asphalt shingles are in poor condition, they could negatively impact the lifespan of your new metal roof. Uneven surfaces or trapped moisture can cause the metal to corrode or deteriorate prematurely.
Increased Weight: Adding a metal roof on top of asphalt shingles increases the overall weight load on your roof structure. It’s essential to ensure that your roof can support the added weight.
Warranty Issues: Some metal roofing manufacturers may void their warranties if their products are installed over existing asphalt shingles. Be sure to check the warranty terms before proceeding.
Potential for Overheating: Dark colored asphalt shingles can absorb heat and transfer it to the underside of the metal roof, potentially reducing the energy efficiency benefits of the metal.
Factors to Consider Before Installing Metal Over Asphalt
Before making a decision, carefully evaluate the following factors:
Condition of the Existing Asphalt Shingles
The condition of your existing asphalt shingles is the most crucial factor to consider. If the shingles are old, brittle, cracked, or severely damaged, installing metal roofing over them is generally not recommended. A sound, relatively flat surface is essential for a successful metal roof installation.
Number of Existing Layers
Most building codes allow for a maximum of two layers of roofing. If you already have two layers of asphalt shingles, you’ll need to remove them before installing metal roofing. Adding a third layer would likely exceed the weight limits of your roof structure and violate local building codes.
Roof Deck Integrity
The roof deck, which is the underlying structure that supports the roofing materials, must be in good condition. Check for signs of rot, water damage, or sagging. If the roof deck is compromised, it needs to be repaired or replaced before installing any new roofing, regardless of whether it’s metal or asphalt.
Local Building Codes
Always check with your local building department to ensure that installing metal roofing over asphalt shingles is permitted in your area. Some municipalities have specific regulations regarding roofing materials and installation methods.
Professional Inspection
It’s highly recommended to have a professional roofing contractor inspect your roof before making any decisions. A qualified contractor can assess the condition of your existing shingles, roof deck, and overall roof structure. They can also advise you on the best course of action and provide an accurate estimate for the project.
Preparation Steps for Installing Metal Over Asphalt
If you decide to proceed with installing metal roofing over asphalt shingles, proper preparation is essential to ensure a successful and long-lasting installation. Here are the key steps involved:
Thorough Inspection and Repairs
Begin with a thorough inspection of the existing asphalt shingles. Identify and repair any minor damage, such as loose or missing shingles. Address any potential problem areas, such as leaks or soft spots. If there are significant problems, it’s best to remove the asphalt shingles and start with a clean slate.
Cleaning the Surface
Clean the surface of the asphalt shingles to remove any dirt, debris, moss, or algae. This will help ensure that the metal roofing materials adhere properly and prevent moisture buildup.
Installing Underlayment
While some argue it’s not necessary, many professionals recommend installing an underlayment over the asphalt shingles before installing the metal roofing. This provides an extra layer of protection against water infiltration and helps create a smoother surface for the metal panels. A synthetic underlayment is generally preferred over traditional felt paper, as it’s more durable and water-resistant.
Installing Furring Strips or Battens (Optional)
In some cases, furring strips or battens may be installed over the underlayment. These are wooden strips that create an air gap between the metal roofing and the asphalt shingles. This air gap can help improve ventilation, reduce heat transfer, and prevent moisture buildup. However, this method is generally used when addressing uneven surfaces or specific drainage concerns.
Cost Considerations
The cost of installing metal roofing over asphalt shingles can vary depending on several factors, including the size and complexity of your roof, the type of metal roofing material you choose, and the labor rates in your area. However, it’s generally less expensive than tearing off the old roof and starting from scratch.
Material Costs
Metal roofing materials come in a wide range of prices, depending on the type of metal, gauge (thickness), and finish. Aluminum is generally the most expensive, followed by copper, steel, and zinc. Steel is a popular choice for its affordability and durability. The gauge of the metal also affects the price, with thicker gauges being more expensive but also more durable.
Labor Costs
Labor costs can vary depending on the complexity of the installation and the experience of the roofing contractor. Installing metal roofing requires specialized skills and equipment, so it’s essential to hire a qualified contractor with experience in metal roofing installations. The amount of preparation needed also influences labor costs. More extensive repairs to the existing asphalt shingles or roof deck will increase the labor costs.
Overall Project Cost
To get an accurate estimate of the overall project cost, it’s best to get quotes from several reputable roofing contractors. Be sure to ask for a detailed breakdown of the costs, including materials, labor, and any other fees. Compare the quotes carefully and choose a contractor who offers a fair price and a solid warranty.
Long-Term Savings
While the initial cost of metal roofing may be higher than asphalt shingles, it’s important to consider the long-term savings. Metal roofs last much longer, require less maintenance, and can lower your energy bills. Over the lifespan of your roof, you may actually save money by choosing metal roofing.
Types of Metal Roofing Suitable for Over-Asphalt Installation
Not all types of metal roofing are equally suitable for installation over existing asphalt shingles. Some styles are better suited than others due to their design, weight, and installation methods. Here are some of the most common types of metal roofing that can be installed over asphalt shingles:
Standing Seam Metal Roofing
Standing seam metal roofing is a popular choice for its sleek, modern appearance and excellent weather resistance. It consists of interlocking metal panels that run vertically along the roof, with raised seams that create a watertight seal. Standing seam is relatively lightweight and can be installed over asphalt shingles with proper preparation.
Metal Shingles or Shakes
Metal shingles or shakes are designed to mimic the look of traditional asphalt shingles or wood shakes, but with the added durability and longevity of metal. They are available in a wide variety of styles and colors. Metal shingles are generally lightweight and can be installed over asphalt shingles, but it’s essential to ensure that the surface is smooth and even.
Metal Tile Roofing
Metal tile roofing is designed to replicate the look of traditional clay or concrete tiles. It’s a durable and attractive option that can add a touch of elegance to your home. Metal tile is heavier than other types of metal roofing, so it’s crucial to ensure that your roof structure can support the added weight before installing it over asphalt shingles.
Corrugated Metal Roofing
Corrugated metal roofing is a cost-effective and versatile option that’s often used on agricultural and commercial buildings. It consists of metal sheets with a wavy or ribbed pattern that provides strength and rigidity. Corrugated metal is lightweight and relatively easy to install, making it a suitable option for installation over asphalt shingles. However, its aesthetic may not appeal to all homeowners.
The Importance of Ventilation
Proper roof ventilation is essential for maintaining the health and longevity of your roof, regardless of whether it’s metal or asphalt. Ventilation helps to regulate temperature and humidity levels in your attic, preventing moisture buildup and reducing the risk of rot, mold, and ice dams. When installing metal roofing over asphalt shingles, it’s crucial to ensure that your existing ventilation system is adequate and functioning properly.
Types of Roof Ventilation
There are several types of roof ventilation systems, including:
Soffit Vents: Soffit vents are located under the eaves of your roof and allow air to enter the attic.
Ridge Vents: Ridge vents are located along the peak of your roof and allow warm, moist air to escape from the attic.
Gable Vents: Gable vents are located on the sides of your house and provide ventilation for the attic.
Turbine Vents: Turbine vents are rotating vents that use wind power to exhaust air from the attic.
Ensuring Adequate Ventilation
When installing metal roofing over asphalt shingles, it’s essential to ensure that your existing ventilation system is adequate to handle the increased moisture levels. The asphalt shingles can trap moisture, so it’s crucial to have enough ventilation to remove it. In some cases, you may need to add additional vents to improve ventilation. A roofing contractor can assess your ventilation needs and recommend the best solution.
Finding a Qualified Roofing Contractor
Installing metal roofing is a complex project that requires specialized skills and equipment. It’s essential to hire a qualified roofing contractor with experience in metal roofing installations. A reputable contractor will have the knowledge, expertise, and equipment to ensure that your metal roof is installed properly and will last for many years to come.
Tips for Finding a Roofing Contractor
Here are some tips for finding a qualified roofing contractor:
Get Referrals: Ask friends, family, and neighbors for referrals to reputable roofing contractors.
Check Online Reviews: Read online reviews on sites like Yelp, Google, and the Better Business Bureau to get an idea of the contractor’s reputation.
Verify Licensing and Insurance: Make sure the contractor is properly licensed and insured in your state.
Get Multiple Quotes: Get quotes from several contractors and compare them carefully. Be sure to ask for a detailed breakdown of the costs, including materials, labor, and any other fees.
Check References: Ask the contractor for references from past clients and contact them to get feedback on their experience.
Read the Contract Carefully: Before signing a contract, read it carefully to make sure you understand all the terms and conditions. Pay attention to the warranty, payment schedule, and cancellation policy.
Metal Roofing Over Asphalt Shingles: The Final Verdict
Installing metal roofing over asphalt shingles can be a viable option for some homeowners, but it’s not a one-size-fits-all solution. It’s crucial to carefully consider the condition of your existing asphalt shingles, the integrity of your roof deck, local building codes, and the potential drawbacks before making a decision. If your existing asphalt shingles are in good condition and your roof deck is sound, installing metal roofing over them can save you money and reduce landfill waste. However, if there are underlying problems, it’s best to remove the asphalt shingles and start with a clean slate.
Ultimately, the best way to determine whether installing metal roofing over asphalt shingles is right for you is to consult with a qualified roofing contractor. A professional contractor can assess your specific situation and provide you with the best advice based on your needs and budget.
Maintenance and Care for Your New Metal Roof
Once your metal roof is installed, proper maintenance and care are essential to ensure its longevity and performance. Metal roofs are relatively low-maintenance, but there are a few things you can do to keep them in good condition.
Regular Inspections
Inspect your roof regularly, especially after severe weather events, such as strong winds, heavy snow, or hail. Look for any signs of damage, such as dents, scratches, or loose panels. Address any minor issues promptly to prevent them from becoming major problems.
Cleaning
Clean your roof periodically to remove any dirt, debris, moss, or algae. Use a soft brush or broom and a mild detergent solution. Avoid using harsh chemicals or pressure washers, as they can damage the metal finish.
Gutter Maintenance
Keep your gutters clean and free of debris to prevent water from backing up onto your roof. Clogged gutters can cause water damage and promote the growth of moss and algae.
Tree Trimming
Trim any trees that overhang your roof to prevent branches from falling on it and causing damage. Tree branches can also trap moisture and debris, which can lead to the growth of moss and algae.
Professional Maintenance
Consider having your roof professionally inspected and maintained every few years. A roofing contractor can identify and address any potential problems before they become serious.
Conclusion
Metal roofing offers numerous benefits, including durability, longevity, energy efficiency, and aesthetic appeal. Installing metal roofing over asphalt shingles can be a cost-effective and environmentally friendly option, but it’s essential to carefully consider all the factors involved and consult with a qualified roofing contractor. With proper preparation, installation, and maintenance, a metal roof can provide decades of reliable protection for your home.