Can You Put a Metal Roof Over Your Old Roof? Pros and Cons

More homeowners in Michigan are starting to realize the benefits and value of metal roofing.  One common question many of them have is how to replace an existing roof that has shingles on it. Can you put a metal roof over shingles? The short answer is yes, but there are several factors to consider. The longer answer depends on your roof’s condition, local building codes, and whether the pros outweigh the cons for your specific home.

Let’s break it down in plain language so you can decide if this option makes sense for your central Michigan property.

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

Certain conditions need to exist if you want to place a metal roof over shingles. The existing roof has to be in decent condition, meaning it must be flat and structurally sound. There can be no major dips or signs, or significant rot or decay.  If your shingles are already curling, soft, or hiding leaks, covering them up will only make problems worse.

Underlying roof structure matters as well. Modern metal roofing is durable and lighter than before, but adding a new layer still increases the overall load. Your roof decking and framing must be able to support the added weight safely. It’s also imperative to understand your city’s local building codes.  In Michigan, most jurisdictions follow the Michigan Residential Code (based on the International Residential Code). Generally, these codes restrict how many layers of roofing material you can have. If your home already has multiple layers of shingles, a tear-off may be required before installing metal.

Finally, ventilation is another factor that shouldn’t be overlooked. Good ventilation allows your roof to last longer because it helps prevent moisture buildup and heat damage. Installing a metal roof over existing shingles without proper ventilation can trap heat and moisture. This can decay the underlying structure.

Advantages Of Installing A Metal Roof Over Shingles

If you’re considering putting a metal roof over your shingles, it provides several benefits.

1. Cost Savings: If you’re hiring a company to install your metal roof, it can save you money by skipping the labor to tear off the existing shingles. Even as a DIY project, it will save you money because you won’t have to pay for the disposal of old shingles. ( like hauling it away).
2. Faster installation: New roof installation can be somewhat of a hindrance for busy homeowners. Placing metal over shingles can significantly reduce installation time.
3. Added insulation: Having an additional layer of roofing material can be an excellent insulator when temperatures in Michigan plunge in the winter season.
4. Less Mess: Tearing off an existing roof can create lots of debris and chaos around the property.

This option is good if you want to save time and money while keeping your home’s exterior in check.

Drawbacks Of Installing a Metal Roof Over Shingles

While covering your existing shingles has its benefits, you should also consider the risks of not removing them first.

1. Concealed issues: There could potentially be underlying issues you’re not aware of, like structural damage, rot, and decay. Laying metal over it could make the issue much harder to repair.
2. Uneven surface:  It’s difficult to lay metal shingles perfectly over existing shingles. If done incorrectly, the metal panels can warp or ripple. This will reduce their aesthetic appearance and functionality.
3. Potential Code Violations: Depending on local ordinances and the number of existing layers, installing a new roof over the old one may violate building codes, leading to problems during resale or insurance claims.
4. No Opportunity for Deck Inspection: When a tear-off is skipped, the roof deck (the foundation under the shingles) cannot be fully inspected for damage, meaning weak or rotted sections may go unnoticed and compromise the new roof’s structural integrity.

How To Make The Best Decision For Your Michigan Property

Ultimately, making the decision to install a metal roof over shingles comes down to the current condition of your roof and considering local codes. It’s often a great choice for sound roofs with only one layer of shingles, offering significant savings and a faster installation. However, if there are existing leaks, structural damage, or multiple layers already present, a complete tear-off is the safer and smarter investment to ensure the longevity and performance of your new metal roof.

Mid-Michigan Metal Sales: Your Trusted Supplier For Metal Roofing Supplies

Whether you’re an experienced contractor or installing a metal roof yourself, we provide the highest quality metal roofing supplies throughout central Michigan and surrounding areas. Browse our online store today or contact us if you have any questions!