DIY Metal Roof: Install Over Shingles (Easy Guide)

Metal roofing offers a durable, long-lasting alternative to traditional asphalt shingles, and understanding its benefits is key. The Roofing Contractors Association (RCA) provides valuable resources for homeowners considering this upgrade, emphasizing best practices for how to install metal roofing over shingles. Correct measuring tools, such as a quality laser level, are essential for proper installation to ensure a professional finish and long-term performance. Home Depot is a key supplier that offers many metal roofing options and tools for the DIYer.

Metal roofing is no longer reserved for commercial buildings and barns. It's rapidly becoming a preferred choice for homeowners seeking a blend of unmatched durability, extended lifespan, and superior energy efficiency. This shift is fueled by the desire for roofing solutions that offer long-term value and resilience against the elements.

One increasingly popular method is installing metal roofing directly over existing asphalt shingles. This approach presents a viable and often cost-effective alternative to complete roof replacement.

This section serves as your gateway to understanding the advantages of this roofing strategy. We will cover from its practical application as a DIY project to the critical importance of adhering to local building codes.

The Allure of Metal: Durability, Longevity, and Efficiency

Metal roofs stand apart from conventional materials, primarily due to their exceptional durability. They can withstand extreme weather conditions, including high winds, heavy snow, and hail, far better than asphalt shingles.

Longevity is another significant advantage. A well-maintained metal roof can last two to three times longer than a traditional asphalt shingle roof, potentially exceeding 50 years or more.

Furthermore, metal roofing offers impressive energy efficiency. Its reflective properties help reduce heat absorption, keeping your home cooler in the summer and potentially lowering energy bills.

Metal Over Asphalt: A Feasible Solution

Installing metal roofing over existing asphalt shingles is more than just a theoretical possibility; it's a practical and increasingly common practice. This method avoids the labor-intensive and costly process of removing the old shingles, saving time and money.

However, feasibility hinges on the condition of the existing roof. A thorough assessment is crucial to ensure the underlying structure is sound and capable of supporting the additional weight of the metal roofing.

The DIY Advantage: Cost Savings and Empowerment

For many homeowners, the prospect of a DIY roofing project is both exciting and daunting. Installing metal roofing over shingles can be a rewarding DIY endeavor, offering significant cost savings compared to hiring professional contractors.

The savings come primarily from reduced labor expenses. However, it's essential to realistically assess your skills, physical capabilities, and comfort level with heights and power tools.

Navigating the Regulatory Landscape: Building Codes and Permits

Before embarking on any roofing project, it is imperative to understand and comply with local building codes. These regulations are in place to ensure the safety and structural integrity of your roof.

Building codes vary from one municipality to another, so thorough research is essential. This includes obtaining necessary permits and adhering to specific installation guidelines. Failure to comply with building codes can result in fines, delays, or even the need to redo the work.

Metal roofing presents a durable and efficient alternative for homeowners, and installing it over existing asphalt shingles offers a practical path forward. However, before diving into the installation process, meticulous planning and preparation are paramount. This stage sets the foundation for a successful and long-lasting roofing project.

Planning and Preparation: Setting the Stage for Success

Proper planning is not just about saving time; it's about ensuring the safety, longevity, and code compliance of your new metal roof. This phase involves a thorough assessment of your existing roof, careful material selection, and a deep dive into local building regulations. Overlooking these steps can lead to costly mistakes and potential safety hazards.

Assessing the Existing Roof: A Foundation Check

Before investing in materials or tools, a comprehensive inspection of your existing asphalt shingle roof is critical. This assessment determines whether your roof is a suitable candidate for a metal overlay.

Begin by carefully examining the asphalt shingles for signs of damage. Look for:

• Rot: Soft, decaying spots indicate moisture damage and potential structural weakness.
• Missing shingles: These expose the underlayment and can lead to leaks.
• Curling or buckling: These signs suggest that the shingles are nearing the end of their lifespan.
• Granule loss: Excessive granule loss reduces the shingle's protective capabilities.

If widespread damage is present, consider a complete roof replacement instead of an overlay.

More importantly, evaluate the structural integrity of the roof deck. Walk across the roof to identify any soft or sagging areas, indicating potential rot or weakness in the underlying plywood or OSB. A compromised roof structure cannot adequately support the added weight of a metal roof, potentially leading to structural failure. Consult a structural engineer or roofing professional if you have any doubts about the roof's load-bearing capacity.

Gathering Necessary Materials and Roofing Tools

Once you've confirmed that your existing roof is structurally sound, the next step is to gather the necessary materials and tools. Accurate measurements and careful material selection are essential to avoid waste and ensure a proper fit.

Calculating Material Needs

Begin by calculating the square footage of your roof. This measurement will determine the amount of metal roofing needed. Add extra material (approximately 10%) to account for overlaps, cuts, and potential errors.

Selecting the Right Metal Roofing

Choosing the right type of metal roofing is crucial. Common options include:

• Standing seam: Offers a sleek, modern look and excellent weather resistance.
• Corrugated metal: A more traditional and cost-effective option.

Consider factors such as aesthetics, budget, and local climate when making your selection.

Fasteners and Underlayment

• Fasteners (screws, nails): Select the correct type of fasteners specifically designed for metal roofing to ensure a secure and watertight attachment.
• Roofing underlayment: This provides an essential moisture barrier between the old shingles and the new metal roof. Choose a high-quality synthetic underlayment for optimal protection.

Essential Roofing Tools

Equip yourself with the appropriate tools:

• Measuring Tape: For accurate measurements and cuts.
• Shears/Metal Cutting Tools: For trimming the metal panels.
• Ladder: For safe access to the roof.
• Safety Glasses
• Gloves

Safety Equipment: Your Shield of Protection

Roofing work is inherently dangerous, so prioritizing safety is non-negotiable. Invest in essential safety equipment to minimize the risk of accidents.

• Gloves: Protect your hands from sharp edges and rough surfaces.
• Safety Glasses: Shield your eyes from debris and flying particles.
• Hard Hat: Protect your head from falling objects.
• Fall Protection Harness: This is crucial when working on sloped roofs. Secure the harness to a reliable anchor point to prevent falls.

Decoding Local Building Codes: Navigating the Regulatory Maze

Before starting any roofing project, it's imperative to research local building codes and permit requirements. Roofing regulations vary significantly from one municipality to another.

Contact your local building department to inquire about:

• Permit requirements: Many jurisdictions require permits for roofing work.
• Installation standards: Local codes may specify requirements for materials, fasteners, and installation techniques.

Failing to comply with building codes can result in fines, project delays, and even the need to redo the work.

When to Call the Pros: Consulting with Roofing Contractors

While installing metal roofing over asphalt shingles can be a DIY project, certain situations warrant professional assistance.

Consider consulting a roofing contractor if:

• Your roof has a complex design with multiple slopes, dormers, or chimneys.
• You have concerns about the structural integrity of your roof.
• You are unfamiliar with roofing techniques or building codes.

A professional contractor can ensure proper installation, code compliance, and long-term performance. They can also identify and address potential problems that you might overlook. While there’s an added cost, the peace of mind and assurance of a job well done are worth the investment.

Step-by-Step Installation Guide: Laying the Foundation for a Durable Roof

With the planning complete and materials in hand, the transformation truly begins. Installing a metal roof over existing asphalt shingles is a meticulous process demanding precision and adherence to best practices. This section provides a detailed, actionable guide to ensure a successful and long-lasting installation.

Preparing the Existing Roof: Setting the Stage

A clean and sound surface is essential for the new metal roof. Proper preparation ensures a smooth and secure overlay.

• Cleaning the Asphalt Shingles: Begin by thoroughly cleaning the existing asphalt shingles. Remove all loose debris, such as leaves, twigs, and dirt. A broom, leaf blower, or even a gentle pressure washer (used with caution) can be employed.

• Addressing Minor Repairs: Carefully inspect the asphalt shingles for any minor damage. Small tears or curled edges can be secured with roofing cement. However, if widespread damage is present, reconsider the overlay and opt for a complete roof replacement.

Installing Roofing Underlayment: Creating a Moisture Barrier

Underlayment serves as a critical moisture barrier, protecting the roof deck from water intrusion. Choose a high-quality synthetic underlayment designed for metal roofing.

• Applying the Underlayment: Starting at the eaves, roll out the underlayment horizontally across the roof. Ensure it is smooth and wrinkle-free.

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• Overlapping and Fastening: Overlap each subsequent layer of underlayment by the manufacturer's recommended amount (typically 6 inches). Secure the underlayment with roofing staples or nails, spacing them according to the manufacturer's instructions. Pay close attention to proper fastening, as this prevents wind uplift and water penetration.

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Cutting and Installing Metal Roofing Panels: Precision is Key

Accuracy in cutting and installing metal roofing panels is paramount for a weathertight and aesthetically pleasing roof.

• Measuring and Cutting: Using a measuring tape, accurately measure the roof and determine the required panel lengths. Employ shears or specialized metal cutting tools to cut the panels to the desired size. Always wear safety glasses when cutting metal to protect your eyes.

• Installing the Panels: Begin installing the panels at one edge of the roof, following the manufacturer's instructions. Ensure proper alignment and overlap between panels, creating a weathertight seal. Different types of metal roofing (standing seam, corrugated) will have specific installation techniques.

• Ensuring Proper Alignment and Overlap: Proper alignment and overlap are critical to preventing water intrusion. Check the manufacturers installation guide on the recommended dimensions for overlapping and spacing.

Securing the Metal Roofing with Fasteners: Locking in Longevity

The choice and placement of fasteners directly impact the longevity and structural integrity of the metal roof.

• Selecting the Right Fasteners: Use screws or nails specifically designed for metal roofing. Ensure they are compatible with the type of metal and the roof deck material.

• Proper Spacing: Space the fasteners according to the manufacturer's instructions, typically every 12-24 inches. Over- or under-tightening can compromise the seal and lead to leaks.

Navigating Roof Penetrations: Sealing for a Watertight Fit

Roof penetrations, such as chimneys and vents, require careful flashing to prevent water intrusion.

• Flashing Techniques: Use appropriate flashing materials (metal or rubber) to seal around chimneys, vents, and other penetrations. Cut and shape the flashing to fit snugly against the penetration and the roofing panels.

• Ensuring a Watertight Seal: Apply roofing sealant liberally around the flashing to create a watertight seal. Regularly inspect these areas for any signs of leaks, especially after heavy rain or snow.

Installing Flashing: Guarding Against the Elements

Flashing is the unsung hero of any roofing system. Installing it correctly can make all the difference between a dry, secure roof and a leaky one.

• Valley Flashing: Valleys are prime locations for water accumulation. Install wide valley flashing beneath the metal panels, ensuring it extends far enough to direct water away from the roof structure.

• Step Flashing: Where the roof meets a wall, use step flashing interweaving it with the metal panels and the wall siding to create a watertight barrier.

Capping the Ridge: The Crowning Touch

The ridge, the highest point of the roof, requires a special cap to protect it from the elements.

• Ridge Cap Installation: Install the ridge cap according to the manufacturer’s instructions. Overlap each piece of the cap properly, and use appropriate fasteners with sealant washers.

• Preventing Leaks: Apply a bead of sealant along the edges of the ridge cap to ensure a watertight seal. This final step protects the entire roofing system and adds a polished, professional look.

Finishing Touches and Inspection: The Path to Perfection

With the metal roofing panels securely in place, the bulk of the installation is complete. However, achieving a truly weather-resistant and aesthetically pleasing roof requires careful attention to the final details. These finishing steps and a thorough inspection are crucial for maximizing the longevity and performance of your new metal roof.

Sealing Gaps and Seams: Fortifying Against the Elements

Even with meticulous installation, small gaps and seams can exist, particularly around roof penetrations, flashing, and panel overlaps. These vulnerabilities can allow water to infiltrate, leading to leaks, corrosion, and ultimately, roof failure.

Therefore, sealing these potential entry points with a high-quality, weather-resistant sealant is paramount.

Choose a sealant specifically designed for metal roofing applications. Polyurethane or silicone-based sealants are generally recommended due to their flexibility, durability, and adhesion properties.

Carefully apply the sealant to all identified gaps and seams, ensuring a complete and watertight seal. Pay particular attention to areas around chimneys, vents, skylights, and any other roof penetrations. These are common trouble spots prone to leaks if not properly sealed.

The Importance of Choosing the Right Sealant

Selecting the right sealant involves considering several factors. First, ensure compatibility with the specific type of metal roofing you've installed. Some sealants can react negatively with certain metals, causing corrosion or discoloration.

Second, consider the sealant's flexibility and ability to withstand temperature fluctuations. Metal expands and contracts with temperature changes, so the sealant must be able to accommodate this movement without cracking or losing its seal.

Finally, opt for a sealant with a long lifespan and resistance to UV degradation. This will ensure that your seals remain effective for years to come, protecting your roof from water damage.

Inspecting for Loose Fasteners and Potential Leaks: A Meticulous Approach

A comprehensive inspection is essential to identify any potential weaknesses in the installation. Begin by systematically examining every fastener (screws or nails) used to secure the metal roofing panels.

Ensure that all fasteners are properly seated and tightened. Loose fasteners can create pathways for water intrusion and compromise the structural integrity of the roof.

Carefully inspect the areas around fasteners for any signs of damage or distortion to the metal panels. This could indicate over-tightening or incorrect fastener placement.

In addition to fasteners, meticulously inspect all seams, overlaps, and flashing details for any signs of gaps, damage, or improper installation. Use a flashlight to illuminate hard-to-see areas and identify potential leak points.

Consider performing a water test to simulate rainfall and identify any leaks. This involves carefully spraying water over the roof surface and observing for any water intrusion inside the building.

Addressing any identified issues promptly is crucial to prevent further damage and ensure the long-term performance of your metal roof.

Removing Debris and Cleaning the Work Area: Leaving a Pristine Finish

The final step in the process is to thoroughly clean the work area and remove any debris generated during the installation. This not only improves the aesthetic appearance of the roof but also prevents potential hazards and ensures proper drainage.

Carefully remove all scrap metal, discarded fasteners, and other construction debris from the roof surface. Use a broom or leaf blower to clear away any loose dirt, dust, or leaves.

Inspect the gutters and downspouts for any obstructions and clear them as needed. Proper drainage is essential to prevent water from pooling on the roof and causing damage.

Finally, clean up any spilled sealant or other materials from the surrounding area. Leaving a clean and tidy work area demonstrates professionalism and respect for your property.

By meticulously completing these finishing touches and conducting a thorough inspection, you can ensure that your new metal roof provides years of reliable protection and enhances the value of your home.