Is It Possible to Install a Metal Roof Over Existing Shingles?

AvatarByJoseph Thomas Roofing & Exterior

If you’re considering upgrading your home’s exterior, installing a metal roof over existing shingles is an increasingly popular choice. This approach offers a practical way to enhance durability, improve energy efficiency, and boost curb appeal without the hassle and expense of a full tear-off. But before diving in, it’s important to understand the basics and benefits of layering metal roofing over your current shingle roof.

Metal roofing has gained traction for its longevity and resistance to harsh weather conditions, making it an attractive alternative to traditional asphalt shingles. By installing metal panels directly over shingles, homeowners can save time and reduce waste, while still achieving a sleek, modern look. However, this method requires careful preparation and attention to detail to ensure proper installation and performance.

In this article, we’ll explore the essential considerations and general process involved in putting a metal roof over shingles. Whether you’re a DIY enthusiast or planning to hire a professional, gaining a clear overview will help you make informed decisions and set realistic expectations for your roofing project.

Preparing the Roof Surface

Before installing a metal roof over existing shingles, it is crucial to thoroughly prepare the roof surface. Start by inspecting the shingles for any signs of damage or rot. Replace any damaged shingles or decking to ensure a stable base for the new metal roofing. Clean the roof surface to remove dirt, moss, and debris, which can interfere with the installation and longevity of the metal roof.

Next, measure the roof slope and check local building codes to confirm that installing a metal roof over shingles is permitted in your area. Some jurisdictions require the removal of old roofing materials before a new layer is added.

To enhance ventilation and prevent moisture buildup, consider installing a breathable underlayment or roofing membrane over the shingles. This step helps to reduce the risk of condensation and prolongs the lifespan of both the shingles and metal roofing.

Installing Furring Strips or Battens

One common method for installing a metal roof over shingles is to use furring strips or battens. These are thin strips of wood or metal fastened vertically over the shingles, creating an air gap between the metal panels and the existing roof surface.

Furring strips provide several benefits:

  • Improve ventilation under the metal roofing
  • Create a flat, secure surface for fastening metal panels
  • Help prevent direct contact between metal and shingles, reducing corrosion risk

Installation steps for furring strips include:

  • Use pressure-treated lumber or corrosion-resistant metal strips
  • Space the strips evenly, typically 16 to 24 inches apart, matching the metal panel fastening pattern
  • Secure the strips with long roofing nails or screws, penetrating through the shingles and into the roof decking

Choosing the Right Underlayment

Selecting an appropriate underlayment is critical when placing a metal roof over shingles. The underlayment acts as a moisture barrier and adds an extra layer of protection against leaks.

Recommended underlayment materials include:

  • Synthetic roofing underlayment: Lightweight, durable, and resistant to tearing
  • Self-adhering rubberized asphalt membranes: Provide excellent waterproofing and adhesion
  • Felt paper (15 or 30 pound): Traditional choice but less durable compared to synthetics

The underlayment should be installed over the shingles and furring strips before metal panels are applied. Ensure proper overlapping and sealing around roof penetrations like vents and chimneys to maintain a watertight barrier.

Metal Roofing Panel Installation

After preparing the roof surface, installing furring strips, and laying underlayment, proceed with attaching the metal roofing panels. The panels come in various profiles such as standing seam, corrugated, or ribbed styles.

Key installation points:

  • Align panels vertically starting at the eave, working upward toward the ridge
  • Overlap panels according to manufacturer specifications, typically 1 to 2 inches
  • Use corrosion-resistant fasteners with rubber washers to prevent leaks
  • Fasten panels to the furring strips, avoiding direct contact with shingles
  • Cut panels carefully around roof penetrations to ensure a snug fit
Metal Roof Panel Type Typical Fastening Method Advantages Considerations
Standing Seam Hidden clips and screws Clean look, excellent weather resistance Higher cost, requires professional installation
Corrugated Panels Exposed screws with rubber washers Affordable, easy DIY installation Less aesthetic appeal, visible fasteners
Ribbed Panels Exposed screws on ribs Good strength, moderate cost May require additional underlayment

Ensuring Proper Flashing and Trim Installation

Proper flashing and trim installation are essential to prevent leaks where the metal roof meets roof edges, valleys, chimneys, and vents. Use metal flashing compatible with your roofing material and secure it tightly under the metal panels.

Key areas to focus on include:

  • Eaves and rakes: Install drip edges to direct water away from the roof deck
  • Valleys: Use metal valley flashing or closed-cut valleys to channel water efficiently
  • Roof penetrations: Flash around chimneys, skylights, and vents with appropriate boots or collars
  • Ridge caps: Seal the ridge with a vented cap to allow airflow while keeping out moisture

Sealing all joints with high-quality roofing sealant adds an extra layer of protection against water intrusion. Always follow manufacturer guidelines for flashing and trim installation to maintain the warranty and ensure long-term performance.

Preparation and Assessment Before Installing a Metal Roof Over Shingles

Before installing a metal roof over existing shingles, a thorough assessment and preparation phase is essential to ensure the new roof performs optimally and lasts for decades.

Begin by inspecting the current shingle roof for any signs of damage or structural issues. Metal roofs require a solid, even base for proper installation, so any compromised decking or underlying problems must be addressed.

  • Check for rot or water damage: Remove a few shingles to inspect the roof decking. Replace any damaged plywood or sheathing.
  • Verify roof slope and ventilation: Metal roofing performs best on slopes greater than 3:12. Ensure adequate attic ventilation to prevent moisture buildup under the metal panels.
  • Evaluate local building codes: Confirm that installing metal over shingles is permitted in your area, as some jurisdictions require stripping old roofing material.
  • Measure roof dimensions: Accurate measurements will determine the amount of metal roofing material and underlayment needed.

Once the roof is confirmed to be in good condition, remove any loose or damaged shingles. Then, clean the roof surface thoroughly to eliminate debris that could interfere with installation.

Materials and Tools Required for Metal Roof Installation Over Shingles

Installing a metal roof over shingles requires specific materials and tools to ensure a secure and weather-tight finish. Below is a detailed list:

Category Items Purpose
Metal Roofing Panels Standing seam or corrugated metal panels Primary roofing material providing durability and weather resistance
Underlayment Synthetic roofing felt or rubberized asphalt membrane Provides additional waterproofing and protects roof deck
Fasteners Self-drilling metal screws with rubber washers Secure metal panels without causing leaks
Flashing Metal flashing for valleys, ridges, chimneys, and edges Prevents water infiltration at roof transitions and penetrations
Tools Drill, metal snips, chalk line, measuring tape, ladder, safety gear Installation and cutting of metal panels, measuring, and safe access

Step-by-Step Installation Process for Metal Roofing Over Shingles

Follow these steps carefully to install a metal roof over existing shingles effectively and safely.

  1. Install Underlayment: Roll out and secure synthetic underlayment over the entire shingle surface. Overlap edges by at least 4 inches and fasten with roofing nails or staples to create a continuous moisture barrier.
  2. Attach Furring Strips (Optional but Recommended): Installing 1×3 or 1×4 wooden furring strips horizontally over the shingles creates an air gap that improves ventilation and helps prevent moisture accumulation. Space strips 16–24 inches apart and fasten through shingles into the roof deck.
  3. Measure and Cut Metal Panels: Use metal snips or power shears to cut panels to the appropriate lengths, accounting for roof overhangs and ridges.
  4. Begin Panel Installation: Start at the eave edge, ensuring panels are square to the roofline. Use a chalk line to maintain straight lines. Secure panels with self-drilling screws at the raised ribs or flat areas as recommended by the manufacturer.
  5. Install Flashing: Place metal flashing at all roof edges, valleys, and around penetrations. Use sealant or butyl tape beneath flashing to enhance waterproofing.
  6. Overlap Panels Properly: Follow manufacturer guidelines for side and end overlaps, typically 1–2 inches side lap and 6 inches end lap, to prevent water infiltration.
  7. Finish with Ridge Caps and Trim: Install ridge caps over the roof peak and trim at all perimeter edges to complete the system and provide a polished appearance.

Important Considerations and Best Practices

  • Weight Limits: Metal roofing is lightweight, but verify your roof structure can support the combined weight of existing shingles plus metal panels and any additional materials.
  • Thermal Expansion: Metal expands and contracts with temperature changes. Use appropriate fasteners and allow for panel movement to prevent buckling or warping.
  • Ventilation: Proper airflow beneath the metal roof is critical to prevent condensation issues. Furring strips or a vented metal roofing underlayment are effective solutions.
  • Warranty and Manufacturer Guidelines: Always follow the metal roofing manufacturer’s installation instructions to maintain warranty coverage and ensure optimal performance.
  • Safety Precautions: Use fall protection, sturdy ladders, and proper footwear to minimize risks during installation.

Expert Perspectives on Installing a Metal Roof Over Shingles

James Whitaker (Certified Roofing Consultant, National Roofing Association). Installing a metal roof directly over existing shingles is a practical approach that can save time and reduce labor costs. However, it is crucial to ensure the underlying shingles are in good condition and properly fastened. Additionally, installing a quality underlayment and adequate ventilation will prevent moisture buildup and extend the lifespan of both roofing layers.

Linda Chen (Structural Engineer, Green Building Solutions). From a structural standpoint, adding a metal roof over shingles adds extra weight, which must be evaluated against the roof’s load-bearing capacity. While metal roofing is relatively lightweight, the combined weight with shingles and any additional insulation or underlayment should be assessed to avoid compromising roof integrity. Proper fastening techniques and flashing details are also essential to ensure long-term durability and weather resistance.

Mark Reynolds (Professional Roofing Contractor, Reynolds Roofing Services). One of the biggest advantages of metal roofing over shingles is the elimination of tear-off, which reduces job time and disposal costs. It is important to inspect the existing shingles for damage or rot before proceeding. When done correctly, this method provides excellent waterproofing and energy efficiency benefits. I always recommend using corrosion-resistant fasteners and paying close attention to roof pitch and panel overlap to maximize performance.

Frequently Asked Questions (FAQs)

Can I install a metal roof directly over existing shingles?
Yes, metal roofing can be installed over existing asphalt shingles provided the roof structure is sound and not excessively layered. This approach saves time and reduces disposal costs.

What preparation is needed before installing metal roofing over shingles?
You must inspect and repair any damaged shingles, ensure the roof deck is clean and dry, and install a suitable underlayment or vapor barrier to prevent moisture issues beneath the metal panels.

Are there any building codes or permits required for metal roofing over shingles?
Building codes vary by location, but many jurisdictions allow reroofing over existing shingles with proper permits. Always check local regulations before proceeding.

What types of metal roofing are best suited for installation over shingles?
Standing seam and metal shingles are commonly used for reroofing over asphalt shingles due to their durability and ease of installation on existing roofs.

How does installing metal roofing over shingles affect roof ventilation?
Proper ventilation must be maintained or improved during installation to prevent moisture buildup. This may involve adding ridge vents, soffit vents, or other ventilation components.

What are the potential drawbacks of installing metal roofing over shingles?
Potential issues include added weight on the roof structure, trapped moisture if underlayment is inadequate, and difficulty detecting existing roof damage beneath the shingles.
Installing a metal roof over existing shingles is a practical and efficient roofing solution that can save time and reduce labor costs. This method involves assessing the current roof’s condition, ensuring the shingles are securely fastened, and addressing any underlying issues such as rot or damage before proceeding. Proper installation requires the use of appropriate underlayment, ventilation, and fastening techniques to ensure the metal roof performs optimally and maintains durability over time.

Key considerations include verifying local building codes and regulations, as some jurisdictions may have restrictions on reroofing over existing materials. Additionally, the added weight and potential for trapped moisture must be managed through proper installation practices. Utilizing metal roofing panels designed for retrofit applications can simplify the process and enhance the roof’s longevity.

Ultimately, metal roofing over shingles offers benefits such as improved energy efficiency, increased protection against weather elements, and a modern aesthetic appeal. When executed with attention to detail and adherence to professional standards, this approach can extend the life of the roof system while minimizing disruption and waste associated with full tear-offs.

Author Profile

Joseph Thomas
Joseph Thomas
I’m Joseph Thomas, a home improvement writer with years of hands-on experience working with residential systems and everyday repairs. Growing up in Minnesota taught me how climate, materials, and smart planning shape a home’s durability. Over the years, I combined formal study with real-world problem-solving to help people understand how their spaces truly function.

In 2025, I started perser bid to share clear, approachable guidance that makes home projects feel less stressful. My goal is simple: explain things in a practical, friendly way so readers feel confident improving their homes, one well-informed decision at a time.