If you have been getting estimates for a roof replacement, you may have encountered one contractor who offers a significantly lower price, and when you look at the details, the difference is that they are proposing to install new shingles directly on top of your existing ones rather than tearing off the old roof first.
It sounds appealing. Less labor, less cost, and your old roof essentially becomes the underlayment for the new one. But in Michigan, and especially for a roof that needs to handle the kind of weather Greater Lansing gets, this shortcut has some real downsides worth understanding before you decide.
Why Roof-Overs Are Allowed at All
Building code in Michigan does allow a second layer of shingles to be installed over an existing layer in most cases — as long as the existing shingles are in reasonably flat condition and the roof deck is structurally sound. So it is not a scam. Some contractors do it legitimately, and in certain situations, it is a reasonable option.
The question is whether it is the right option for your specific roof, your home, and the Michigan climate.
The Problem with Hidden Damage
The most significant issue with a roof-over is that nobody really knows what the existing roof deck looks like under those old shingles. Soft spots, rot, deteriorated underlayment, improperly installed flashing, and ventilation problems; all of those get covered up rather than corrected.
When we do a full tear-off at Capital Roofing, we inspect the decking before anything goes back on. Soft spots get replaced. Damaged sections of OSB or plywood get swapped out. Everything beneath your new shingles is sound. With a layover, you are betting that the hidden layer is in good shape. That bet does not always pay off.
Weight and Structural Load
Asphalt shingles are not light. A standard layer of architectural shingles weighs roughly two to four pounds per square foot. Two layers double that load on your roof structure. For most homes built in Greater Lansing in the last several decades, this is within the design tolerance, but for older homes, homes with any structural concerns, or roofs with longer spans, the added weight is a legitimate consideration.
Michigan winters add significant snow and ice load on top of whatever is already there. Adding a permanent extra layer of shingle weight to that equation is worth factoring in.
Shortened Lifespan of the New Shingles
New shingles installed over old ones run hotter. The existing shingles trap heat, and that elevated temperature accelerates granule loss and asphalt degradation in the new layer. You may find that a 25-year shingle performs more like a 15 or 18-year shingle when it is installed over an existing layer.
There is also the issue of surface conformity. If the existing shingles have any curling, cupping, or uneven wear, the new layer conforms to those irregularities rather than lying flat. Over time, those irregularities become more visible and can create areas where wind gets under the new shingles more easily.
What to Ask Before You Decide
If a contractor is proposing a roof-over, ask them these questions directly: What condition do they believe the decking is in, and how do they know without looking at it? What warranty does the manufacturer provide on shingles installed over an existing layer — some manufacturers reduce or void warranty coverage in this scenario. And what will it cost if hidden decking damage is discovered after the new shingles are already going on?
Get the answers in writing. A lower upfront price that comes with unknown variables and a reduced warranty is not necessarily a better deal.
Our Approach
Capital Roofing does full tear-offs on our replacement jobs. It costs more upfront, but it means we know exactly what we are working with, we can address any underlying issues, and the new roof starts its life properly, with sound decking, fresh underlayment, and ice and water shield installed correctly. That is how we stand behind a 15-year workmanship warranty.
If you have gotten a roof-over proposal and want a second opinion, we are happy to come out, take a look, and give you an honest comparison of what you are being offered.
Ready to schedule your free roof inspection? Call or text Capital Roofing at (517) 896-5872 or visit capitalroofingpro.com. Serving Lansing, East Lansing, Grand Ledge, St. Johns, Okemos, and communities across Greater Lansing.