In today’s housing market, more homeowners are opting for durable, low-maintenance, and energy-efficient roofing solutions. As asphalt shingles age and wear, many homeowners are asking: Can you put a metal roof over old shingles? The answer is yes—in many cases, you can. But as with most construction-related questions, the devil is in the details.
This comprehensive guide from Litespeed Construction, a Knoxville, TN-based roofing authority, explains everything you need to know about installing a metal roof over old shingles—including building codes, pros and cons, installation methods, costs, and more.
Key Takeaways
💡Yes, You Can Install a Metal Roof Over Old Shingles
💡Installing a Metal Roof Over Shingles Is Cost-Effective and Durable
💡Proper Installation and Compliance Are Key
💡Litespeed Construction Is a Trusted Local Expert
Why Consider a Metal Roof Over Old Shingles?
According to the U.S. Census Bureau’s American Housing Survey, the average roof replacement costs $7,000 to $10,000, with many homeowners spending even more for full tear-offs. Installing a metal roof over old shingles can potentially save thousands in labor and disposal fees. Plus, metal roofs are:
- Energy-efficient: Reflective coatings help reduce cooling costs.
- Long-lasting: Many metal roofs last 40–70 years, per the Metal Roofing Alliance (MRA).
- Low maintenance: Less prone to cracking, shrinking, or eroding.
What the Building Codes Say (With Government Sources)
Before moving forward with a metal roof over old shingles, you must ensure compliance with local building codes and regulations.
International Residential Code (IRC) Guidelines
According to the International Code Council (ICC):
“A new roof covering shall not be installed without first removing existing roof coverings where any of the following conditions occur: if the existing roof has two or more layers of any type of roofing.”
— IRC R907.3
This means that in most areas:
- You can install a metal roof over one layer of shingles.
- If there are two or more layers, a tear-off is likely required.
Tennessee State Building Code
Tennessee adopts the IRC with some local amendments. In Knox County and the City of Knoxville, Litespeed Construction complies fully with the Tennessee Department of Commerce and Insurance (TDCI) codes. Always check with local permitting offices or your contractor to verify compliance.
How Is a Metal Roof Installed Over Old Shingles?
Installing a metal roof over old shingles involves either:
- Direct Installation: Metal panels are fastened directly over the existing shingle layer.
- Strapping/Batten System: Wood battens are placed over shingles, and the metal roof is installed on top.
Step-by-Step Installation (Simplified):
Step
1. Inspection
2. Underlayment
3. Battens (Optional)
4. Metal Paneling
5. Final Touches
Description
Ensure existing shingles are flat, no rot or structural damage.
Install vapor barrier or synthetic underlayment.
Wood strips may be added to promote air flow and reduce heat.
Secure panels with appropriate fasteners and flashing.
Ridge caps, trim, and sealants applied for waterproofing.
Benefits of Installing a Metal Roof Over Shingles
| Benefit | Details |
|---|---|
| 💰 Cost Savings | Saves $1,000–$2,000 in tear-off and disposal fees (NAHB data). |
| 🛠️ Faster Installation | Reduces labor hours—projects often completed in 2–3 days. |
| 🧱 Insulation Layer | Shingles act as an additional thermal and sound barrier. |
| 🌱 Eco-Friendly | Less waste goes to landfills; metal roofing is 100% recyclable. |
| 🌦️ Weather Resistance | Excellent resistance to rain, wind, and snow—ideal for East Tennessee. |
Potential Drawbacks & Considerations
Not every roof is a candidate for this method. Here’s what homeowners should consider:
| Drawback | Considerations |
|---|---|
| ⚠️ Weight Concerns | Though metal is light, adding it to shingles increases roof load. |
| 🔍 Trapped Moisture | Improper installation can trap moisture, causing rot or mold. |
| 🧱 Surface Unevenness | Old shingles may cause panels to appear wavy or uneven. |
| 📜 Warranty Limitations | Some manufacturers void warranties if installed over shingles. |
| 🏢 Resale Impacts | Buyers may prefer full replacements; appraisers might value replacements higher. |
Litespeed Construction: Knoxville's Trusted Roofing Experts
Litespeed Construction has been serving the Knoxville, TN area for over a decade. With certified installers, BBB accreditation, and hundreds of five-star reviews, we take pride in being the region’s go-to expert for metal roof over old shingles installations
Our team handles:
- Structural inspections
- Permit acquisition
- Code-compliant installations
- Post-install cleanup
FAQs: Metal Roof Over Old Shingles
Yes, in most jurisdictions including Knoxville, TN—as long as there’s only one existing shingle layer.
It depends. Some manufacturers allow it if installed properly, but always verify with your installer.
Yes. A synthetic underlayment or vapor barrier is typically required to prevent condensation issues.
Usually 2–4 days for most residential roofs, depending on size and weather.
Modern metal roofs with proper insulation are not significantly louder than shingle roofs.
Yes. In fact, standing seam metal roofs are ideal for solar panel installation.
Homeowners typically save $1,000–$3,000 by avoiding tear-off labor and dump fees.
Metal roofs are rated for high winds and have excellent hail resistance—great for East Tennessee’s weather.
Some insurers offer discounts for Class 4 impact-resistant roofs. Ask your agent.
Call us at (865) 297-3286 or visit LitespeedConstruction.com for a free estimate!
Final Thoughts: Should You Install a Metal Roof Over Old Shingles?
Installing a metal roof over old shingles is a cost-effective and durable roofing option for many homes—especially in areas like Knoxville, TN where weather and seasonal shifts can damage traditional asphalt roofing. With expert metal roof installation from Litespeed Construction, homeowners can enjoy peace of mind, enhanced energy efficiency, and long-lasting protection.
