If you’re considering upgrading to a metal roof, you’ve likely wondered: can you put a metal roof over shingles? The answer is yes—in many cases, installing a metal roof over shingles is not only possible but also offers significant advantages. One of the biggest benefits of metal roofing is its lightweight construction, making it the perfect material to install over an existing asphalt shingle roof without requiring complete tear-off and removal.
However, before you proceed with installing a metal roof over your existing shingles, there are several important considerations to evaluate. Understanding local building codes, assessing your current roof’s condition, and choosing the right installation method will ensure your new metal roof performs optimally for decades to come.
Key Advantages of Installing Metal Roof Over Shingles
Installing a metal roof over shingles offers several compelling benefits that make it an attractive option for homeowners and building owners:
Cost Savings: Eliminating the tear-off process significantly reduces labor costs and disposal fees. Removing old shingles can account for a substantial portion of roofing project expenses, so keeping them in place delivers immediate savings.
Time Efficiency: Without the need to strip away existing roofing materials, installation proceeds much faster. Most shingles retrofitting projects can be completed more quickly than traditional tear-off and replacement, minimizing disruption to your daily routine.
Environmental Benefits: Keeping old shingles out of landfills reduces environmental impact. Millions of tons of asphalt shingles end up in landfills each year, so choosing to roof over existing materials represents a more sustainable approach.
Additional Insulation and Protection: The existing shingle layer provides an extra barrier that can improve insulation values and reduce energy costs. This dual-layer system offers enhanced protection against heat transfer and weather infiltration.
Can You Put a Metal Roof Over Shingles? Yes, But There are Some Essential Considerations First
Before making any decisions in answer to the pressing question, “can you put a metal roof over shingles,” consider the following closely:
Does Your Local Building Code Allow It?
Be sure to check with your local building department on what they do and do not allow when it comes to retrofitting. Building codes vary significantly by location, and some jurisdictions restrict or prohibit installing new roofing over existing materials. Your city, parish, or county building department can provide specific guidance on what’s permitted in your area.
Even if the practice is generally allowed, there may be specific requirements regarding installation methods, ventilation, or the number of roofing layers permitted. Verifying code compliance should be your first step—discovering that your local code doesn’t allow this installation method after you’ve already planned and budgeted for it can derail your entire project.
Is Your Existing Roof Structure Sound?
Your new metal roof is only as strong as the foundation supporting it. When you install a metal roof over shingles, the fasteners must penetrate through the existing shingles and into solid structural decking beneath. A compromised foundation will undermine the integrity of your entire metal roof installation.
- Inspect for structural damage: Look for signs of sagging, water damage, or rot in the roof decking. If the plywood or OSB sheathing underneath shows significant deterioration, you’ll need to address these issues before proceeding with a metal roof installation.
- Check for water damage: Water stains on ceilings, mold growth, or musty odors in your attic indicate moisture problems that must be resolved. Installing new roofing over a damaged substrate simply conceals problems rather than solving them.
- Assess shingle condition: While faded, cracked, or crumbly shingles don’t necessarily prevent metal roof installation, they can signal underlying issues. As long as the structural decking remains solid, the surface condition of existing shingles is less critical.
How Many Roofing Layers Are Currently in Place?
Most building codes limit the total number of roofing layers allowed on a structure. These restrictions exist because roof trusses and structural supports are engineered to bear specific weight loads. Exceeding these limits by adding too many roofing layers can compromise structural integrity and potentially cause truss failure.
If your current roof already has multiple layers of shingles, you may be required to remove all existing materials before installing your new metal roof. Check with your local building code enforcement office to determine the maximum number of roofing layers permitted in your area. According to the International Residential Code (IRC) many U.S. jurisdictions generally limit re-roofing to no more than two layers of roofing materials without a tear-off.
Staying informed about codes concerning roofing layers will help you understand the question “can you install a metal roof over shingles” or if complete removal may be necessary instead.
How to Install a Metal Roof Over Shingles: Two Proven Methods
But can you install a metal roof over shingles with multiple installation techniques? Good news—there are two primary approaches for successfully installing metal roof over shingles, each with distinct advantages depending on your specific situation.
Determining the Best Installation Method for Your Project
Choosing between installation methods depends on several factors specific to your building and situation:
- Roof condition: If your existing shingle roof has significant irregularities or waves, the batten method provides better results by creating a level installation plane.
- Climate considerations: In hot climates, the ventilation gap created by battens offers substantial energy efficiency benefits by preventing heat transfer to your building interior.
- Budget constraints: Direct installation over underlayment typically costs less than the batten method due to reduced materials and labor requirements.
- Long-term performance goals: If maximizing your roof’s lifespan and energy efficiency are priorities, the investment in battens often proves worthwhile through reduced cooling costs and extended roof life.
Method 1: Direct Installation with Underlayment
The first method involves installing a new synthetic underlayment that runs over and completely covers the existing shingles. This underlayment serves multiple important functions:
Water protection: The underlayment provides an additional waterproofing layer, offering extra protection against moisture that might seep under the metal roofing panels.
Buffer layer: It acts as a protective barrier between the textured shingle surface and the smooth metal panels. Since metal expands and contracts with temperature changes, and asphalt shingles have a rough, sandpaper-like texture, direct contact can cause the metal to wear over time.
Smooth surface: The underlayment creates a more uniform surface for metal panel installation, improving the finished appearance and performance.
Without this underlayment buffer, the abrasive texture of shingles could gradually wear down the underside of your metal roofing, potentially compromising its weather resistance and longevity. This protective layer ensures your metal roof maintains its integrity regardless of thermal expansion and contraction.
Method 2: Installation Using Battens or Purlins
The second method for installing a metal roof over shingles uses horizontal battens (also called purlins or strapping). These wood or metal strips are fastened directly through the existing shingles into the structural roof deck, creating an elevated framework for attaching metal panels.
This approach offers several significant advantages:
Level installation surface: Battens compensate for irregularities in the existing shingle roof, providing a flat, consistent surface for metal panel attachment. This ensures proper panel alignment and appearance.
Ventilation air gap: The space created between the old shingle roof and new metal roof allows air circulation. This ventilation gap prevents heat transfer from the metal roof to the shingles below, reducing the risk of accelerated shingle deterioration and improving overall energy efficiency.
Radiant barrier option: The air space created by battens provides an ideal location for installing radiant barrier insulation. This reflective material can dramatically reduce heat transfer into your building during hot weather, lowering cooling costs.
Enhanced drainage: The elevated installation allows any moisture that penetrates the metal roofing to drain away from the building structure rather than becoming trapped between roofing layers.
Important Steps Before Beginning Your Metal Roof Installation
So, can you put a metal roof over shingles? Absolutely—but first you’ll want to make sure you take notice of each of the following steps:
1. Verify Local Requirements and Obtain Permits
Contact your local building department to understand all applicable codes and permit requirements. Building inspectors can provide valuable guidance on approved installation methods and help you avoid costly mistakes. Most jurisdictions require permits for roofing projects, and installing work without proper permits can create problems when selling your property or filing insurance claims.
2. Conduct a Thorough Roof Inspection
Before deciding whether you can put a metal roof over shingles, have a qualified roofing professional inspect your existing roof structure. This inspection should evaluate:
- Structural decking condition and integrity
- Evidence of water damage or rot
- Adequate ventilation in the attic space
- Current roofing layer count
- Flashing condition around chimneys, vents, and other penetrations
3. Choose Quality Materials
Selecting appropriate materials ensures your metal roof installation succeeds. Consider factors such as:
Panel profile: Different metal panel styles suit various architectural designs and performance requirements.
Gauge thickness: Heavier gauge metal provides greater durability but increases cost and weight.
Coating systems: High-quality finishes protect against corrosion and fading while reflecting solar heat.
Fastener quality: Use fasteners specifically designed for metal roofing with proper sealing washers to prevent leaks.
Choosing Walker Metals for Your Next Metal Roofing Project
Every roofing project presents unique challenges and requirements, especially when it comes to installing a metal roof over shingles. Whether you’re a DIY enthusiast ready to tackle installation yourself or prefer professional installation services, Walker Metals provides the expertise, quality materials, and support you need for success.
When asking the question, “can you install a metal roof over shingles” our experienced team understands the complexities of this choice and can guide you through every decision. We offer:
- Premium metal roofing materials in various profiles and colors
- Expert technical guidance on installation methods
- Recommendations tailored to your specific building and climate
- Quality fasteners, underlayment, and accessories
- Support for both DIY and professional installations
To determine the best installation approach for your metal roof over shingles project, contact the roofing experts at Walker Metals today. Our knowledgeable staff will help you navigate local building codes, select appropriate materials, and choose the installation method that delivers optimal performance and value for your investment.
So, can you put a metal roof over shingles on your own? Absolutely, but remember we’re here to help you do it right. Get in touch with us at (225) 791-7791 to receive a free estimate and to discuss your project in depth. Discover how metal roofing can transform your building while saving you time and money throughout its entire lifespan.
