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How much are roofers per hour? Can I install new shingles over old?

Apr 8, 2025 | Uncategorized

Hattiesburg MS Roofers

Can I install new shingles over old?

If your roof is showing signs of wear and you’re starting to think about replacing it, you might be wondering: “Can I install new shingles over old ones?” The short answer is yes, in some cases you can. But before you decide to go this route, there are important factors to consider. In this article, we’ll explore when it’s acceptable to install new shingles over old ones, the pros and cons of doing so, and how to make the best decision for your home.

Is It Legal to Install New Shingles Over Old Ones?

Yes, installing a new layer of shingles over an existing one—also known as a re-roof or overlay—is legal and permitted by building codes in most areas, as long as:

  • Your roof has only one layer of existing shingles.

  • The structure can support the added weight.

  • The existing shingles and decking are in good condition (no major damage, rot, or soft spots).

Always check with your local building department and roofing contractor to make sure you’re in compliance with local codes.

Pros of Installing New Shingles Over Old

✅ Lower Cost
Installing new shingles over old ones can save money because it eliminates the labor and disposal costs associated with tearing off the old roof.

✅ Faster Installation
Since there’s no tear-off involved, the job can typically be completed more quickly—sometimes in just a day or two.

✅ Less Mess
A re-roof creates less debris, dust, and disruption to your yard or driveway.

Cons of Installing New Shingles Over Old

❌ Shorter Lifespan
Shingles installed over old ones may not last as long. The uneven surface can reduce the new layer’s ability to adhere properly, leading to premature wear.

❌ Hidden Damage
Covering up old shingles can hide problems like leaks, rot, or mold, which may worsen over time and result in costly repairs.

❌ Added Weight
Two layers of shingles are significantly heavier than one. If your roof structure isn’t built to handle the extra weight, it can create long-term structural issues.

❌ No Inspection Opportunity
Tearing off old shingles allows your roofer to inspect and repair the roof deck. Skipping this step means any underlying problems go unnoticed.

When It’s Okay to Install Over Old Shingles

You may consider a re-roof if:

  • There is only one existing layer of shingles.

  • The existing shingles are flat, not curled or damaged.

  • The roof deck is solid, with no water damage or sagging.

  • You’re looking for a short-term solution or are on a tight budget.

When You Should Tear Off the Old Roof

You should opt for a full roof replacement if:

  • There are two or more layers of shingles.

  • The existing shingles are cracked, curled, or missing.

  • You’ve had leaks, soft spots, or mold in your attic.

  • You want to install metal roofing or another material that requires a smooth surface.

  • You’re planning to stay in your home long-term and want the best performance.

Conclusion

While it is possible to install new shingles over old ones, it’s not always the best choice. A re-roof can save money upfront, but it may come with trade-offs in terms of longevity, performance, and the ability to detect hidden damage. Consulting a professional roofer is the best way to determine whether your roof is a good candidate for an overlay or if a full tear-off is the smarter long-term investment.

If you’re unsure which option is right for you, contact a licensed roofing contractor to inspect your roof and provide expert guidance.

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