Metal roofing has become a popular choice among homeowners due to its durability, energy efficiency, and sleek appearance. For those with an existing shingle roof, you might wonder if it’s possible to install metal roofing over shingles instead of removing them. The good news? In many cases, knowing how to install a metal roof over shingles is a practical option that saves time and money.
In this blog, we’ll explore why you might want to consider covering your asphalt shingles with a metal roof, when it’s a good idea (and when it isn’t), and provide a step-by-step guide to the roof installation process. Whether you’re a DIY enthusiast or planning to hire professionals, this guide will help you understand the ins and outs of installing metal roofing over shingles.
Why Install a Metal Roof Over Shingles
Replacing a roof can be expensive and time-consuming, especially when you consider the additional labor of tearing off existing shingles. Installing a metal roof over shingles is an alternative that offers several benefits while minimizing hassle. But why would someone choose this approach? Here are just a few reasons:
- Cost Savings: Skipping the tear-off process reduces labor and disposal costs significantly. By leaving the existing shingles in place, homeowners can save on overall project expenses.
- Time Efficiency: Removing shingles can be time-intensive. By installing metal roofing directly over the old roof, the project moves faster, meaning less disruption for the homeowner.
- Environmental Impact: Tearing off shingles generates a considerable amount of waste. Keeping the shingles intact helps reduce the materials sent to landfills, making it a more eco-friendly choice.
- Extra Insulation: The existing shingles act as an additional insulating layer, which can help regulate indoor temperatures. This can enhance the energy efficiency of the metal roofing system.
- Enhanced Curb Appeal: Metal roofs provide a sleek, modern look that can increase your home’s value and aesthetic appeal. Covering an old, worn shingle roof with pristine metal panels instantly improves your home’s appearance.
While there are many reasons to consider installing a metal roof over shingles, it’s not the right solution for every home. That’s why it’s essential to evaluate your roof’s condition and suitability before proceeding.
Can You Install a Metal Roof Over Shingles?
The short answer is yes—you can install metal roofing over shingles, but there are specific factors to consider. Not every roof is a candidate for this method, and installing metal without proper preparation can lead to costly problems down the line. Here’s what you need to know about when this method works and when it doesn’t.
When You Can Install Metal Roofing
- Roof Structure is Sound: The underlying structure must be in good condition. This includes the roof deck, trusses, and framing. A solid base ensures the new roof will perform as expected.
- Shingles are in Good Shape: If the existing shingles are relatively flat and free from significant damage, they can serve as a stable foundation for the metal roof. Minor imperfections can be smoothed out with an underlayment or furring strips.
- Local Building Codes Permit It: Some areas have specific regulations about how many layers of roofing are allowed. Check with your local building authority to ensure compliance.
- Proper Ventilation: Metal roofs require adequate ventilation to prevent moisture buildup. If the current ventilation system is sufficient, it can remain in place.
When Installing Metal Roofing over Asphalt Shingles Doesn’t Work
- Severely Damaged Shingles: Shingles that are curling, cracked, or rotting are a poor base for metal roofing. Installing over-damaged shingles can compromise the integrity of the new roof.
- Structural Issues: If the roof deck or supports show signs of sagging, rot, or other damage, these issues must be addressed before installation.
- Poor Roof Design: Complex rooflines or excessive layers of shingles may make it impractical to install a metal roof over the existing one.
By evaluating your roof’s condition beforehand, you can determine if this installation method is suitable for your home. Consulting with a roofing professional is the best way to ensure your roof is ready for a metal upgrade.
How to Install a Metal Roof Over Shingles
Installing a metal roof over shingles involves several steps, each of which requires precision and careful attention to detail. Here’s a step-by-step guide to help you understand the installation method:
Inspect the Roof
Before starting, thoroughly inspect the roof. Ensure the existing shingles are in good condition and the roof structure is sound. Look for signs of damage, such as sagging or rotting wood.
Add Underlayment (if needed)
Lay a breathable underlayment over the shingles. This layer serves as a moisture barrier and helps smooth out minor imperfections in the shingles, creating a flat surface for the metal panels.
Install Furring Strips
Furring strips, or battens, are installed horizontally across the roof to create a level surface and provide ventilation beneath the metal panels. These are particularly useful if the shingles are uneven.
Prepare the Metal Panels
Measure and cut the metal panels to fit your roof’s dimensions. Pre-drill holes as needed for screws to ensure a seamless fit.
Secure the Panels
Starting from the bottom of the roof, attach the metal panels using screws and washers. Overlap each panel slightly to create a watertight seal. Be sure to follow the manufacturer’s instructions for fastening.
Install Flashing and Trim
Add flashing around roof edges, vents, and chimneys to prevent water infiltration. Finish with trim pieces to give the roof a clean, polished look.
Inspect the Completed Roof
Once the panels are in place, perform a final inspection. Check for gaps, loose fasteners, and proper alignment to ensure the roof is secure and ready to handle the elements.
Final Note
While this guide outlines the process, not every roof is suitable for covering with metal roofing. A thorough inspection by a professional is crucial to determine whether this method will work for your home.
FAQs About Installing Metal Roofing Over Shingles
1. Is it legal to install a metal roof over shingles?
Yes, in most areas, it’s legal as long as local building codes allow it. Always check with your local authority before starting a project.
2. Will a metal roof add too much weight to my house?
No, metal roofing is one of the lightest roofing materials on the market, so weight is typically not an issue.
3. Do I need an underlayment when installing metal roofing over shingles?
Yes, underlayment is essential to provide a moisture barrier and smooth surface for the metal panels.
4. Can I install metal roofing over multiple layers of shingles?
Generally, it’s not recommended to install over multiple layers of shingles. Excess layers can create an uneven surface and cause issues with the new roof.
5. How long does a metal roof last compared to shingles?
Metal roofs can last 40-70 years or more, significantly longer than the 20-30 years you can expect from an asphalt shingle roof.
Upgrading to a metal roof over your existing shingles is a great way to improve your home’s durability, energy efficiency, and curb appeal. However, not every roof is a candidate for this method, which is why a professional inspection is essential.
Contact Mountaintop Metal Roofing today for a free inspection to see if your home is suitable for installing metal roofing over shingles. If a tear-off is needed, we’ll provide a free estimate and ensure your new roof is installed with the highest quality craftsmanship. Call now to get started!