15December 2025
You get a quote for a new roof that is thousands of dollars cheaper than the others. The contractor says, “We’ll just nail the new roof right over the old one.” It sounds like a great deal, right?
This is called a “roof over” or “overlay.” While it saves money on labor and disposal fees today, it is often a financial trap waiting to spring a few years down the road.
At T.A. Hughes III Roofing, we believe in doing the job right the first time. We are pulling back the curtain on the hidden dangers of re-roofing over old shingles and why a full tear-off is the only way to truly protect your South Jersey home.
The “Roof Over” Myth: Why Is It So Tempting?
We get it. A full roof replacement is a big investment. An overlay is cheaper because the crew doesn’t have to spend a day ripping off old shingles and paying to haul them to the dump.
But think of it like painting over a rusty car. It looks shiny for a year or two, but the rust underneath is still eating away at the metal.
Is it legal? Yes. New Jersey building codes generally allow for a maximum of two layers of roofing material. But just because it’s legal doesn’t mean it’s smart. If your home already has two layers, adding a third is illegal and dangerous.
Danger #1: Trapping the “South Jersey Sweat” (Heat Damage)
Asphalt shingles are designed to absorb heat from the sun. When you install a second layer on top of the first, you create a heat trap.
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The Science: That heat gets stuck between the layers like a thick wool blanket in July.
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The Result: This excess heat “cooks” the new shingles from the bottom up. They can curl, crack, and lose their protective granules years earlier than they should.
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Local Context: In Gloucester County, our humid summers accelerate this process. A roof that should last 25 years might fail in just 15 if it’s installed over an old layer.
Do you have premature curling shingles? Learn about our Roof Repair Services.
Danger #2: The Invisible Rot (Decking Blindness)
The most critical part of your roof isn’t the shingle—it’s the wood deck underneath.
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The Risk: If your plywood decking has water damage or rot, an overlay hides it. You are essentially nailing a heavy new roof into weak, crumbling wood.
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Consequence: Leaks will return quickly because the underlying problem wasn’t fixed. Worse, nails may pop out because the rotten wood can’t hold them, leading to blown-off shingles during the next storm.
Don’t guess about your roof’s condition. Schedule a thorough roof inspection today.
Danger #3: The Weight of Winter (Structural Stress)
Asphalt shingles are heavy. A single layer weighs roughly 250–350 pounds per “square” (100 sq. ft.). Adding a second layer adds thousands of pounds of “dead load” to your home’s structure.
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The Threat: Add a heavy, wet snowstorm in Burlington County (like the ones we get in February), and that weight doubles or triples.
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The Risk: Older homes in historic towns like Collingswood often have older framing (2×4 rafters) that wasn’t built to hold this combined weight. This can lead to sagging rafters or even structural cracks.
Danger #4: The Resale & Warranty Nightmare
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Resale: Home inspectors always check for layers. When you sell your home, a roof with two layers is a major “red flag.” Buyers will demand a lower price because they know they will have to pay for a double tear-off later.
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Warranty: Most major manufacturers (like GAF) severely limit their warranty coverage on overlays. Because the surface isn’t perfectly flat, the shingles don’t seal as well, which can void your wind warranty coverage.
Learn more about protecting your investment on our Roofing Warranties page.
Why T.A. Hughes III Recommends a “Tear-Off”
We almost always recommend a complete tear-off. Here is our process:
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Strip the Roof: We remove everything down to the deck.
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Inspect the Wood: We find and replace any rotten plywood so your new roof has a solid foundation.
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Modern Protection: We install modern Ice & Water Shields directly to the deck—something you can’t do with an overlay.
A tear-off costs more upfront, but it costs less per year because the roof lasts longer and protects your home better.
Frequently Asked Questions
Q: Is it illegal to put a second layer of shingles on a roof in NJ? A: It is legal up to two layers. However, if you already have two layers, you absolutely must tear them off before installing a new roof.
Q: How much cheaper is a layover roof vs a tear off? A: You might save 20-25% initially on labor and disposal, but you face a 100% higher removal cost when the roof fails early, as you’ll have to pay to remove two layers at once.
Q: Can you put metal roofing over old shingles? A: Technically yes, using strapping to create a gap, but we still recommend removal. Leaving old shingles prevents us from inspecting the deck for rot, which can compromise the new metal roof.
Don’t Let a “Cheap” Quote Cost You a Fortune
Don’t cut corners on your home’s protection. A fresh start with a tear-off ensures your roof lasts for decades.
Get an honest assessment of your roof’s condition. Contact T.A. Hughes III for a Consultation in South Jersey