In most cases, yes. While it is technically possible to install a metal roof over existing shingles, doing so prevents proper underlayment installation and voids most manufacturer warranties. A full tear-off gives your new metal roof the clean, stable foundation it needs to perform correctly for decades.
A homeowner in the Champaign County area recently called us to explore roof replacement options, including both asphalt shingles and metal roofing. One of the first questions that came up was whether the old shingles had to come off first. It is one of the most common questions we hear, and the answer matters a lot more than most people realize.
At White Roofing and Contracting, we have been installing roofs in central Illinois for a long time. Here is what we tell every homeowner who asks this question.
Can You Install a Metal Roof Over Existing Shingles?
Technically, yes, but we do not recommend it and we will not warranty a roof installed that way. Some contractors will lay metal directly over old shingles to save time and labor costs. The problem is that this traps moisture, creates an uneven surface, and prevents the specialized underlayment that metal roofing systems require.
Metal roofing is not like asphalt. It expands and contracts with temperature changes. Without the right underlayment installed over a clean deck, that movement can cause problems over time including leaks, fastener failure, and premature wear.
Why Does the Underlayment Matter So Much for Metal Roofing?
Metal roofing systems require a specific underlayment designed to handle thermal movement, moisture, and noise, and you simply cannot install it correctly over a layer of old shingles. This is especially true for standing seam metal roofs, which use hidden fasteners and rely on a smooth, even surface beneath them.
The standing seam system is the approach we use on residential homes. Unlike exposed fastener metal panels, which screw directly through the metal surface, standing seam panels lock together and hide the fasteners completely. That means no exposed penetrations that can work loose or let water in over time. But that system only works the way it is supposed to when it is installed on a properly prepared deck.
Thinking about a full roof replacement? This is exactly the kind of detail that separates a roof that lasts from one that causes headaches down the road.
What Happens During a Proper Metal Roof Tear-Off?
The process starts with stripping everything down to the decking so we can inspect the plywood or OSB underneath before anything new goes on. Here is what that typically involves:
- Removing all existing shingles and underlayment
- Inspecting the roof deck for soft spots, rot, or damaged plywood
- Making any necessary deck repairs before proceeding
- Installing the appropriate underlayment for the metal system being used
- Installing the metal panels with proper fastening and sealing
Older homes, especially farmhouses common across central Illinois, often have plywood decking installed during a previous re-roof. That is actually a good foundation, but it still needs to be inspected and properly prepped before a metal roof goes on top.
Does This Apply to Asphalt Shingle Replacements Too?
For asphalt shingles, there is more flexibility, but a tear-off is still the right call if you want a warranty-backed installation. Most manufacturers allow one layer of shingles over an existing layer, but we will not warranty a layover installation either. The reason is the same: we cannot fully inspect the deck, and we cannot guarantee what is underneath.
If your home already has two layers of shingles, a full tear-off is required by code before adding another layer.
Is a metal roof more expensive than asphalt shingles?
Yes, metal roofing, particularly standing seam with hidden fasteners, carries a higher upfront cost than architectural asphalt shingles. However, metal roofs typically last significantly longer and require less maintenance over time. The right choice depends on your budget, your timeline, and how long you plan to stay in the home.
Can I get estimates for both metal and asphalt shingles at the same time?
Absolutely. We regularly put together estimates for both options so homeowners can compare them side by side. Even if you are not ready to replace your roof for a year or two, having those numbers helps you plan and budget with confidence.
Will my estimate still be accurate if I wait a year or two before doing the project?
Material and labor costs can shift over time, so we always update estimates before a project moves forward. We keep records on file and will refresh the numbers when you are ready. That way you are always working from current pricing.
Our team has decades of experience with both metal and asphalt roofing across central Illinois, and we are happy to walk you through every option without any pressure.
Ready to Get a Roof Estimate Near Sidney, IL?
Whether you are leaning toward a standing seam metal roof or a traditional architectural shingle replacement, we will give you a straight answer on what your project actually involves and what it will cost. No guesswork, no shortcuts.
Contact White Roofing and Contracting to request your estimate. We serve homeowners throughout the Sidney, IL area and the surrounding Champaign County region, and we are glad to help you plan ahead so there are no surprises when you are ready to move forward.