How To Install Metal Roofing Over Shingles

Installing a metal roof over shingles can be a cost-effective and efficient way to upgrade your home’s roofing system. Metal roofing offers durability, longevity, and energy efficiency benefits, making it an increasingly popular choice among homeowners. In this comprehensive guide, we will walk you through the step-by-step process of installing metal roofing over shingles, highlighting important considerations, safety measures, and tips for a successful installation.

Things You Need to Know Before Installing Metal Roofing Over Shingles

• Metal roofing can be installed over one layer of shingles, but not over multiple layers in some places.
• The roof deck must be inspected and repaired if necessary before installing metal roofing.
• The type of metal roofing and installation method will depend on the slope of the roof.
• Proper ventilation is important when installing metal roofing over shingles to prevent moisture buildup.
• Metal roofing can be noisy during rain or hail storms, but sound-deadening materials can be installed to reduce noise.
• Installing metal roofing over shingles may require additional building permits and inspections.

Pre-Installation Preparations

Before you begin the installation process, there are several crucial preparatory steps to ensure a smooth and successful project.

Roof Inspection and Repair

1. Inspect the Existing Roof: Thoroughly examine the condition of your current shingle roof. Look for signs of damage, such as cracked or missing shingles, water leaks, or structural issues. Address any problems before proceeding.
2. Repair Damages: Replace damaged or deteriorated shingles, and fix any underlying problems. A solid foundation is essential for the metal roofing installation.

Choose the Right Metal Roofing Material

1. Select Metal Type: Choose the metal material that suits your preferences and budget. Options include steel, aluminum, copper, and zinc. Consider factors like durability, weight, and aesthetic appeal.
2. Choose the Profile: Select the profile or style of metal roofing you prefer. Options range from traditional corrugated panels to more modern standing seam designs.
3. Measure and Calculate: Accurately measure your roof’s dimensions to determine the amount of metal roofing material needed. Add extra for overlaps, trim, and potential errors.

Safety Precautions

Safety should always be a top priority when working on your roof. Take these precautions to minimize risks during the installation process.

Use Appropriate Safety Gear

1. Protective Clothing: Wear long sleeves, pants, and sturdy work boots to safeguard against sharp edges and debris.
2. Headgear: A hard hat provides protection from falling objects and bumps.
3. Gloves and Eye Protection: Use gloves for handling materials and tools, and wear safety glasses to shield your eyes.

Work in Optimal Weather Conditions

1. Avoid Extreme Weather: Schedule the installation during mild weather conditions. Avoid working on rainy, windy, or excessively hot days.
2. Secure Ladders: Ensure ladders are stable and placed on a flat surface. Use ladder stabilizers if necessary.

Installation Steps

Now that you’ve completed the preparations and safety measures, let’s dive into the step-by-step installation process.

Gather Necessary Tools and Materials

1. Metal Roofing Panels: Ensure you have the correct type and amount of metal panels.
2. Fasteners: Choose appropriate screws or nails for your metal roofing material and substrate.
3. Underlayment: Install a synthetic underlayment over the shingles to provide an additional moisture barrier.
4. Trim and Flashing: Prepare trim pieces and flashing to protect roof edges, valleys, and penetrations.

Install the Underlayment

1. Clean the Roof Surface: Clear debris and ensure the roof surface is clean before laying the underlayment.
2. Roll Out the Underlayment: Start at the eaves and roll out the underlayment horizontally, overlapping each row by a few inches. Secure it with fasteners.

Attach the Metal Roofing Panels

1. Begin at the Eaves: Start installing the metal panels at the eaves, allowing a slight overhang.
2. Fasten the Panels: Secure each panel with appropriate fasteners, following the manufacturer’s guidelines. Avoid over-tightening screws to allow for expansion and contraction.
3. Overlap and Seal: Ensure each panel overlaps the previous one according to the manufacturer’s specifications. Apply sealant or tape in the overlaps to prevent water infiltration.

Install Trim and Flashing

1. Install Eave Trim: Attach eave trim along the eaves of the roof, securing it in place.
2. Add Ridge Cap: Install the ridge cap along the roof’s peak, ensuring a watertight seal.
3. Apply Flashing: Install flashing around roof penetrations, such as chimneys and vents, to prevent water leaks.

Finishing Touches

1. Check Alignment: Regularly check the alignment and positioning of the metal panels to ensure a uniform appearance.
2. Install Gable Trim: Attach gable trim to the edges of the roof for a polished look.

Benefits of Installing Metal Roofing Over Shingles

Longevity and Durability

Metal roofing offers exceptional durability, often lasting two to three times longer than traditional shingle roofs. It can withstand harsh weather conditions, including heavy snow, rain, and strong winds.

Energy Efficiency

Metal roofs reflect sunlight and heat, reducing the amount of heat transferred into your home. This can lead to lower energy consumption and reduced cooling costs.

Environmentally Friendly

Metal roofing is often made from recycled materials and can be fully recycled at the end of its life. This makes it a sustainable choice for eco-conscious homeowners.

Special Considerations for Flat or Low-Slope Roofs

While installing metal roofing over shingles offers numerous benefits, special considerations come into play when dealing with flat or low-slope roofs. These types of roofs have unique challenges that require specific techniques and precautions to ensure a successful and watertight installation.

Importance of Proper Drainage

Flat or low-slope roofs have a limited pitch, which means water drainage is slower compared to steep-slope roofs. Proper drainage is critical to prevent water pooling, which can lead to leaks and structural damage.

1. Roof Pitch Adjustment: Before installing metal roofing, evaluate the existing pitch of the roof. If feasible, consider adjusting the pitch slightly to enhance water runoff.
2. Use of Underlayment: Install a high-quality waterproof underlayment beneath the metal panels to provide an additional layer of protection against water infiltration.

Choose the Right Metal Profile

1. Standing Seam: Opt for a standing seam metal roofing profile. This design has raised seams that interlock, providing better resistance against water penetration.
2. Avoid Exposed Fasteners: Minimize the use of exposed fasteners, as they can create potential points of entry for water. Standing seam systems and concealed fasteners are preferable.

Enhanced Flashing and Sealants

1. Flashing at Transitions: Pay special attention to areas where the roof transitions, such as parapet walls and vents. Install flashing to create a watertight seal.
2. Sealant Application: Apply a high-quality sealant to all seams, joints, and penetrations. This extra layer of protection helps prevent water from seeping through.

Consider Roof Coatings

1. Reflective Coatings: Apply a reflective roof coating to the metal surface. These coatings not only enhance energy efficiency by reflecting sunlight, but also provide an added barrier against water.
2. Elastomeric Coatings: Elastomeric coatings can bridge small gaps and hairline cracks in the metal panels, further reducing the risk of water infiltration.

Professional Consultation

1. Roofing Contractor Expertise: Due to the complexity of flat or low-slope roofs, consider consulting with a professional roofing contractor experienced in metal roof installations.
2. Engineering Assessment: In some cases, it might be necessary to consult a structural engineer to ensure the roof can bear the additional weight of the metal roofing system.

Tips for Maintaining Your Metal Roof

Once you’ve successfully installed a metal roof over shingles, proper maintenance is essential to ensure the longevity, performance, and appearance of your roofing system. Here are valuable tips to help you maintain your metal roof and protect your investment.

Regular Inspections

1. Scheduled Check-ups: Perform visual inspections at least twice a year, ideally during spring and fall, to assess the condition of your metal roof.
2. Post-Weather Inspections: After severe weather events, such as storms or heavy snowfall, conduct immediate inspections to identify potential damage.

Clear Debris

1. Remove Leaves and Debris: Clear leaves, branches, and debris from your roof regularly to prevent water accumulation and potential damage to the metal surface.
2. Gutter Maintenance: Keep gutters and downspouts clear to ensure proper water drainage from the roof.

Address Rust and Corrosion

1. Surface Rust: Remove minor rust spots using a wire brush and apply a rust-inhibiting primer and paint to prevent further corrosion.
2. Metal Compatibility: Avoid combining incompatible metals, such as copper and steel, to prevent galvanic corrosion.

Maintain Sealants and Fasteners

1. Check Sealants: Inspect and replace damaged or deteriorated sealants around seams, joints, and penetrations to maintain a watertight barrier.
2. Tighten Fasteners: Regularly inspect and tighten any loose screws or fasteners to prevent panels from becoming dislodged.

Prevent Moss and Algae Growth

1. Trim Overhanging Trees: Trim tree branches to prevent excessive shade and moisture buildup, which can promote moss and algae growth.
2. Zinc Strips: Install zinc strips near the roof ridge to inhibit the growth of moss and algae.

Professional Maintenance

1. Scheduled Professional Inspections: Consider hiring a roofing professional for comprehensive inspections and maintenance, especially if you’re unsure about identifying potential issues.
2. Professional Cleaning: Schedule periodic professional cleaning to remove dirt, debris, and potential contaminants from the roof surface.

Avoid Foot Traffic

1. Minimize Walking: While metal roofs are durable, avoid unnecessary foot traffic to prevent denting or scratching the surface.
2. Use Proper Footwear: If walking on the roof is necessary, use soft-soled shoes or crawl boards to distribute your weight evenly.

Maintain Surrounding Landscape

1. Trim Overhanging Branches: Trim trees near the roof to prevent branches from scraping against the metal surface during windy conditions.
2. Clean Gutters and Downspouts: Properly functioning gutters and downspouts prevent water overflow that could potentially damage the roof.

Document Maintenance

1. Keep Records: Maintain a record of inspections, maintenance activities, and any repairs performed on the roof. This documentation can be valuable for warranty claims or future reference.
2. Warranty Compliance: Follow the manufacturer’s recommended maintenance procedures to ensure your warranty remains valid.

Conclusion

Installing metal roofing over shingles can be a rewarding project that enhances your home’s aesthetics, durability, and energy efficiency. By following the step-by-step guide and adhering to safety precautions, you can achieve a successful installation that will provide long-lasting protection and beauty for years to come. Remember, if you’re unsure about any aspect of the installation process, it’s always a good idea to consult with a professional roofing contractor for guidance.