Metal Roofing Over Shingles: What Homeowners Need to Know
One common question many homeowners ask is whether they can install metal roofing over shingles to save on labor costs and disposal fees. The answer is yes, but under specific conditions. Installing metal roofing over an existing roof can be a viable installation method that reduces tear-off labor and material waste while providing excellent protection and energy efficiency.
However, this approach isn’t suitable for every home. Success depends on factors like the underlying structure, local building codes, and the condition of your existing shingles. Understanding when this installation process works and when it doesn’t helps you make an informed decision for your roofing project and avoid costly mistakes later on.
This guide explores everything New Mexico homeowners need to know about installing metal roofing over shingles, including benefits, limitations, and code requirements.
Can You Install Metal Roofing Over Shingles?
Yes, you can install a metal roof over shingles, and it’s permitted in many areas when specific conditions are met. The existing shingles essentially serve as an additional underlayment layer, which can save significantly on labor required for tear-off and disposal.
However, several critical factors must be evaluated first. The roof structure needs to support the combined weight of metal panels over existing materials. Any moisture issues, old shingles, or structural damage must be addressed before installation. Proper ventilation also becomes crucial to prevent moisture buildup and heat accumulation between roofing layers.
New Mexico local building codes typically require a professional contractor to inspect your roof decking and ensure compliance. The roof framing must handle both the old roof and the new metal roof panels, especially considering wind uplift and regional weather conditions.
Most importantly, this approach only works for homes with one existing layer of asphalt shingles in good condition. If there are multiple layers or signs of water infiltration, a complete tear-off process is required before a new metal roof can be installed correctly.
In simple terms, this means your roof must be structurally sound, dry, and properly ventilated before adding a new layer.
Pros of Installing Metal Roofing Over Shingles
Installing metal roofing over an asphalt shingle roof offers several compelling benefits for qualified homes:
- Cost savings: Avoiding the tear-off process reduces labor costs and disposal fees.
- Faster installation: The installation process is quicker since the old roof isn’t being removed.
- Added insulation: The existing shingles and roofing layers can improve soundproofing and energy efficiency, keeping your home cooler in summer and warmer in winter.
- Environmental benefits: Covering an old roof instead of removing it reduces waste and supports sustainable building practices.
Additionally, keeping asphalt shingles in place can provide a stable base for furring strips and other materials that help ensure the metal panels are installed correctly.
For New Mexico homes with a single existing layer and proper preparation, this approach can be a smart move that saves money while maintaining durability.
Cons and Limitations
While installing metal roofing over shingles offers clear benefits, there are also important drawbacks to consider.
- Hidden damage: Leaks or structural issues beneath old shingles may go unnoticed, leading to costly repairs or water damage later.
- Added weight: The combined load of asphalt shingles and metal panels can strain older roof decking or framing not built for multiple layers.
- Ventilation concerns: Without proper airflow, trapped heat and moisture can damage both the metal panels and underlying materials. Given New Mexico’s climate, ensuring proper ventilation is non-negotiable.
- Warranty and insurance limitations: Some warranties or insurance policies require a full tear-off to maintain coverage. Always double-check with your contractor and insurer before proceeding.
- Complex future maintenance: Multiple roof layers make future repairs or replacements more complicated, as the next roof installation will require a complete tear-off.
By understanding these potential issues ahead of time and consulting an experienced roofing contractor, you can make a confident, informed decision for your home.
When Installing Metal Over Shingles Is Not Recommended
Installing metal roofing over shingles is not ideal for every home. Avoid this installation method if:
- Your old roof has more than one layer of asphalt shingles.
- The decking shows rot, sagging, or water infiltration.
- The home lacks proper ventilation or has a history of leaks.
- The underlying structure cannot support the combined weight of metal panels.
In such cases, the tear-off process ensures safety, compliance, and long-term protection. Removing old shingles allows your contractor to inspect the underlayment, fix any leaks, and reinforce the roof structure to prevent costly repairs later.
Code and Inspection Requirements in New Mexico
New Mexico local building codes (based on the International Residential Code) allow metal roofing over shingles when specific code requirements are met. The existing roof must be dry, stable, and free of damage or moisture buildup. Only one existing layer is permitted.
A professional inspection ensures the roof structure can bear the combined weight of both the shingle roof and the metal roof. Installers must also ensure the fasteners are long enough to penetrate the decking and that furring strips are used if necessary for proper ventilation.
Before you install metal, always check local building codes to ensure compliance. A qualified contractor familiar with New Mexico roofing codes will help determine whether this installation method is appropriate for your home and will minimize hidden risks.
Why Choose East Mountain Roofing for Metal Roofing Installation
At East Mountain Roofing, we understand the nuances of installing metal roofing over shingles. Our team performs a full inspection to evaluate your existing roof, verify code requirements, and assess the underlying structure before any work begins.
We use the right materials and proven installation process to ensure your metal roof panels are installed correctly. Our local expertise in New Mexico building codes helps prevent costly mistakes, water leaks, and future maintenance issues.
We offer metal roofing systems designed to handle wind uplift, intense sunlight, and other regional challenges, providing the durability and energy efficiency metal roofs are known for. Each project includes manufacturer warranties up to 30 years and our 10-year labor guarantee for lasting protection.
Upgrade Smart: Metal Roofing Over Shingles Done Right
Installing metal roofing over an asphalt shingle roof can be an excellent option when done safely and installed correctly.
The key lies in proper preparation, using the right materials, and hiring a skilled contractor who understands New Mexico’s local building codes.
By partnering with professionals like East Mountain Roofing, you can avoid costly repairs, reduce energy consumption, and enjoy a new metal roof that keeps your home cooler and better protected year-round.
Ready to get started? Contact us today to install a metal roof that adds value, beauty, and long-term protection to your home.