Can You Install a New Roof Over an Old One? Pros, Cons & NJ Regulations

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Reroofing vs. Replacement in NJ

Can You Install a New Roof Over an Old One in NJ?

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If your roof is showing signs of age or damage, you may be wondering if you can install a new roof over the existing one instead of paying for a full tear-off.

This process, known as reroofing, is sometimes permitted in New Jersey—but it’s not always the best or legal choice.

At LGM Roofing, we believe in helping NJ homeowners make informed decisions. Here’s everything you need to know about reroofing in NJ, including the pros, cons, and state regulations you need to follow.

What Is Reroofing?

Reroofing is the process of installing new shingles over an existing layer of roofing, rather than tearing the old roof off entirely. It’s often chosen as a quicker, less expensive option to full roof replacement.

But is it right for your home?

✅ Pros of Reroofing in NJ

Lower Cost
No tear-off = lower labor and disposal fees

Faster Installation
Reroofing can often be completed in 1 day

Less Disruption
Great for occupied homes or tight schedules

Temporary Fix
Ideal for short-term homeowners or real estate investors

❌ Cons of Reroofing

Shorter Lifespan
New shingles won’t last as long if installed over old ones

Potential Hidden Damage
Moisture, mold, or rot beneath old shingles won’t be visible or fixed

Added Weight
Two layers of shingles = extra stress on the roof structure

Voided Manufacturer Warranty
Some shingle warranties require installation on a clean deck

NJ Roofing Laws & Regulations for Reroofing

New Jersey allows reroofing — but only under certain conditions.

Here’s what you need to know:

1. No More Than Two Layers of Shingles Allowed

Per NJ building code, you cannot install a third layer of shingles. If your home already has two, a full tear-off is required.

2. Roof Deck Must Be in Good Condition

Your roofer must inspect the decking (wood underneath the shingles). If it’s rotted or water-damaged, tear-off is legally required.

3. Permits Are Still Required

Most towns in NJ require a roofing permit, even for reroofing. LGM Roofing handles this for you as part of our process.

🔍 Should You Reroof or Replace?

Let’s simplify it:

ConditionRecommendation
One layer of shingles, no major damageReroofing may be OK
Two layers already on the roofFull replacement only
Decking is rotted or softFull replacement needed
You want long-term durabilityReplace the roof
You plan to sell in 1–2 yearsReroofing may suffice

Still not sure? We offer free inspections to assess your roof’s structure, layers, and lifespan.

Key Takeaways:

✔️Reroofing is legal in NJ — if you only have one layer of shingles

✔️It’s faster and cheaper, but comes with risks like hidden damage

✔️A full tear-off is required if you have two layers or decking issues

✔️Permits are required in most towns (and we handle them for you!)

Always consult with a licensed roofing contractor in NJ before making a decision

Trust LGM Roofing for Honest, Code-Compliant Advice

We don’t cut corners. If reroofing is a safe, smart option for your home, we’ll let you know. If a full replacement is needed, we’ll explain why and deliver results that protect your investment for decades.

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