As a long-time supplier of corrugated metal roofing panels, we know contractors and roofers are often asked, “Can you install a metal roof over a traditional shingled roof?”
In most cases, the answer is yes. You can usually put a new corrugated metal roof over an existing shingled roof. This is one of the many reasons metal roofs keep growing in popularity – their installation doesn’t require completely tearing off the existing roof. By installing a corrugated metal roof over shingles — often referred to as a “roof-over”— your crew saves both time and money while also using an attractive, more energy-efficient, durable, and sustainable roofing material that requires minimal maintenance over its lengthy lifetime.
The upside of metal roofing
Particularly when compared to traditional shingles, corrugated metal roofing has many advantages that make it a smart choice. Those include:
Durability & Longevity: Corrugated metal roofing is renowned for its exceptional durability and longevity, making it a popular choice for various construction applications. Composed of galvanized steel, aluminum, or other metal alloys, corrugated roofing exhibits remarkable resistance to harsh weather conditions, including heavy rain, snow, hail, and intense sunlight. The corrugated design enhances structural integrity by providing additional strength and rigidity, preventing sagging or damage under the weight of accumulated precipitation.
Also, the materials used in corrugated metal roofing are typically resistant to corrosion and rust, ensuring a prolonged lifespan with minimal maintenance requirements. The robust nature of this roofing solution makes it well-suited for both residential and industrial structures, offering long-term protection and cost-effectiveness. With proper installation and periodic maintenance, corrugated metal roofing can endure for several decades, making it a sustainable and reliable choice for those seeking a durable roofing solution.
Improved Energy Efficiency: Corrugated metal roofs significantly enhance energy efficiency in residential settings. The reflective properties of metal, particularly when coated with reflective finishes, enable corrugated roofs to deflect sunlight and reduce heat absorption effectively. This, in turn, helps maintain lower temperatures within the living space, reducing the need for extensive air conditioning during hot weather.
Further, the design of corrugated roofing often includes an air gap between the metal sheets and the underlying structure. This ventilation space acts as a thermal barrier, preventing the transfer of heat into the building.
Metal roofs are also known for their ability to shed snow easily, preventing the formation of ice dams that can compromise insulation and increase heating costs. By promoting a more stable indoor climate and decreasing reliance on heating and cooling systems, corrugated metal roofs contribute to energy conservation and result in long-term cost savings.
Aesthetics: Corrugated metal roofing not only provides a practical solution for roofing upgrades but can also be a solution for clients wanting a modern and stylish appearance. The unique texture and sleek lines of corrugated metal create a contemporary look that complements various architectural styles, from traditional to industrial-inspired designs. This versatile roofing option offers a fresh and distinctive visual appeal, enhancing the overall curb appeal of a home.
Moreover, the durability and resilience of metal roofing panels contribute to their long-lasting attractiveness. Unlike traditional roofing materials that may degrade over time, metal panels maintain their original appearance for years, resisting weathering, fading, and damage from the elements.However, there are several factors to consider if you are considering putting a metal roof over shingles:
Structural Soundness: First and foremost, check the structural integrity of the current roof. You must assess whether the existing structure can support the added weight. While metal roofing is lightweight compared to traditional roofing materials, it’s still necessary to evaluate the load-bearing capacity of the current roof framework to be sure it can bear the additional weight without compromising its integrity. Reinforcements or modifications may be necessary to ensure that the transition to metal roofing is seamless and safe.
Compatibility and Building Codes: Understanding local building codes and regulations is equally vital, and this is particularly important if you work in several jurisdictions. Certain municipalities have specific guidelines regarding roofing materials and installations. Ensuring compliance with these codes not only guarantees the homeowners’ safety but also avoids potential legal issues down the line.
By prioritizing structural soundness and adhering to local building codes, you can guide your clients through a roofing transformation that not only enhances aesthetics but also ensures the long-term stability and durability of their homes.
Installing the New Roof, Step-by-Step
Once you’ve determined the current roof can support it, installing corrugated metal roofing over an existing shingled roof involves a systematic process to ensure a secure and durable outcome. Whether you’re a seasoned pro at roof-overs or never done one, review the proper procedure. Here’s an overview of the key steps involved in the installation:
- Cleaning and Repairs: Clean the shingles to remove debris and inspect for any loose or damaged shingles. Make necessary repairs to ensure a smooth and even surface for the metal roofing installation. Any underlying issues, such as leaks or rot, should be addressed at this stage.
- Installation of Underlayment: Apply a high-quality roofing underlayment over the existing shingles. The underlayment serves as an added barrier against moisture and helps prevent leaks. It also provides a smooth surface for installing the corrugated metal panels.
- Installation of Battens or Purlins: To create an air gap between the metal panels and the shingles, install horizontal battens or purlins over the underlayment. This gap promotes ventilation and prevents moisture buildup, increasing the longevity of the roofing system.
- Metal Roofing Panel Installation: Begin installing the corrugated metal panels, starting from the bottom edge, and working upwards. Fasten the panels to the battens using appropriate screws or nails, ensuring that they are securely anchored to the roof structure. Pay attention to the manufacturer’s guidelines for panel overlap and fastening methods.
- Flashing and Trim Installation: Install metal flashing around roof penetrations, edges, and intersections to prevent water infiltration. Use specialized trim pieces to finish the edges of the roof and create a clean, polished appearance. Properly sealed and secured flashing is crucial for maintaining the weather resistance of the roof.
- Sealing and Weatherproofing: Seal all seams, joints, and fastener points with proper sealants to enhance the weatherproofing of the roof. This step is crucial for preventing water intrusion and ensuring the long-term durability of the metal roofing system.
- Final Inspection: Conduct a thorough inspection of the entire roofing installation to make certain all panels are securely fastened, seams are properly sealed, and flashing is correctly installed. Address any issues immediately to guarantee the effectiveness of the metal roofing system.
By following these steps with precision and attention to detail, roofers can avoid mistakes and successfully install corrugated metal roofing over existing shingles.
It’s also important to consider your crew’s safety, and working with metal panels is quite different than traditional shingles. Here are some tips to keep in mind during the installation process, especially if you’re new to using metal roofing:
- Be Weather Wary: Avoid working on a wet or windy day, as wet surfaces can be slippery, and wind can make handling large metal panels a challenge.
- Mindful Walking on Roof Surface: When walking on the roof, step on the lower portion of the corrugated panels where they are supported by the underlying structure. Avoid stepping on the raised portions, as this can lead to damage or bending of the panels.
- Beware of Sharp Edges: Corrugated metal panels can have sharp edges, especially during cutting and handling. Use caution to avoid cuts or abrasions. Wear appropriate protective gear, and handle metal panels carefully to minimize the risk of injury.
- By prioritizing safety throughout the corrugated metal roof installation process, you can significantly reduce the risk of accidents and injuries, ensuring a secure and successful project.
Choosing the right type and gauge of metal is also important when delving into a corrugated metal roofing installation. Along with the type of metal that is best suited for each project, you’ll want to consider several other factors to decide what product is ideal for your application:
Coating and Finish: Consider the coating and finish options available for the metal. Coatings like Kynar 500 or Hylar 5000 provide excellent weather resistance and color retention. Keep these in mind when guiding homeowners toward a finish that complements the architectural style of their home.
Also, if going green is part of the motivation for using a metal roof, some come with reflective coatings that can contribute to energy efficiency by reducing heat absorption. This can be particularly beneficial in hot climates, helping to lower cooling costs.
- Gauge Thickness: The gauge of the metal determines its thickness. A lower gauge number indicates a thicker material. The appropriate gauge depends on factors such as the expected snow load, wind conditions, and the structural capacity of the roof. Thicker gauges offer more durability but may be heavier.
- Consider Your Climate: Different types of metal are better suited for certain climates. For example, if you’re in an area with heavy snowfall, you may need a thicker gauge to withstand the weight. For a beach house on the ocean, corrosion-resistant metals like aluminum or galvalume may be preferable.
- Investment: Budget plays a significant role in the type and gauge of metal used, and it’s important your clients understand exactly what materials they are getting. While some metals may be more expensive upfront, they may offer long-term cost savings due to their durability and minimal maintenance requirements.
- Architectural Style: Different metals and finishes can complement various architectural designs. For instance, copper may be well-suited for traditional or historic homes, while steel or aluminum might be preferable for modern designs.
- Manufacturer’s Warranty: Check the warranty offered by the manufacturer. A comprehensive warranty shows the confidence the manufacturer has in the product’s durability and performance.
Work with the Weather
The best time to install a new corrugated metal roof, weatherwise, is during dry and mild weather conditions. Ideally, schedule your installations when there is the least risk of precipitation, extreme temperatures, or high winds, as these factors can affect the installation process and the performance of the roofing material. For example, high temperatures can make the metal panels hot to handle. Cold weather can make materials less pliable, potentially complicating the job.
Regular maintenance tasks such as cleaning debris from the roof surface and gutters, inspecting for signs of corrosion or damage, and addressing any potential issues promptly, contribute to the roof’s resilience against the elements.y staying proactive with maintenance, homeowners can prevent small problems from escalating into larger, more costly issues. Additionally, supporting the integrity of sealants, fasteners, and flashing helps uphold the roof’s weather-resistant properties, safeguarding the home itself from leaks and water damage. A thorough and consistent maintenance plan not only keeps metal roofs looking good but is also a savvy investment in long-term durability and protection.
Opting for a roof-over presents a practical and cost-effective solution that can result in considerable time and cost savings for contractors and homeowners alike. The versatility of corrugated metal, coupled with a range of material options, finishes, and profiles, allows for customization that enhances curb appeal – a win for you and your customer.
However, it is important to approach this choice with careful consideration of the existing roof’s condition, structural integrity, and local building codes. This innovative approach combines practicality and style while offering a sustainable roofing solution for homeowners seeking both durability and a modern aesthetic.
In addition, you need quality metal roofing panels. If you’re ready to learn how CMI’s products, experience, and innovation will enhance your next roofing project, get in touch today