How Many Years Does Attic Insulation Last? Here's What You Need to Know

Attic insulation isn’t something most homeowners think about until something goes wrong. But the truth is, it's one of the unsung heroes of your home's energy efficiency. The catch? It doesn’t last forever.

So, how many years does attic insulation last? The answer depends on a few factors, like the type of insulation you have, your local climate, and how well it was installed.

Let’s break it down.

Lifespan of Different Types of Attic Insulation

1. Fiberglass Batt Insulation

   Estimated lifespan: 15 to 20 years (sometimes longer) Fiberglass is the pink fluffy stuff you’ve probably seen in attics. It’s affordable and effective, but over time, it can compress, shift, or get damaged by moisture or pests. If it stays dry and undisturbed, it can last a couple of decades — but efficiency may drop with age.

2. Cellulose Insulation

   Estimated lifespan: 20 to 30 years This type is made from recycled paper and is blown into attic spaces. It settles over time and can be vulnerable to moisture. Still, when installed properly and kept dry, cellulose can outperform fiberglass in both insulation value and longevity.

3. Spray Foam Insulation (Closed Cell)

   Estimated lifespan: 30 to 80+ years Spray foam is the heavy-duty option. It expands into cracks, seals air leaks, and resists moisture and pests. Because of its durability, spray foam can outlive most other insulation types — sometimes even outlasting the roof above it.

4. Mineral Wool (Rock Wool)

   Estimated lifespan: Around 30 years Mineral wool is fire-resistant, moisture-resistant, and more rigid than fiberglass. It holds its shape well and doesn't break down as quickly, making it a reliable long-term option for attic insulation.

Signs It's Time to Replace Your Attic Insulation

Even the best insulation wears down eventually. Here are some clear warning signs that your attic insulation might need an update:

• Higher-than-usual energy bills

• Uneven indoor temperatures or persistent drafts

• Visible mold, mildew, or damp spots

• Insulation that looks compressed or has shifted

• Pest droppings or nests in the attic

If you spot any of these, it’s worth getting a professional inspection.

Why Just Adding More Insulation Isn’t Always the Answer?

It might be tempting to pile more insulation on top of what's already there, but that can actually do more harm than good if the old insulation is damp, moldy, or infested. You could end up sealing in moisture or covering up a bigger problem.

Always get an assessment before adding anything new. In some cases, removing and replacing the old insulation is the better route.

Tips to Help Your Insulation Last Longer

• Keep your attic dry and well-ventilated

• Fix roof leaks promptly

• Seal air leaks before insulating

• Keep pests out with proper attic sealing

• Schedule regular inspections every few years

Taking care of your attic insulation isn't complicated, but it does require a bit of attention. Good insulation = lower energy bills and a more comfortable home.

Bottom Line: How Many Years Does Attic Insulation Last?

On average, attic insulation can last anywhere from 15 to 30 years, depending on the type. Spray foam can push well beyond that. But age isn't the only factor — moisture, pests, and poor ventilation can speed up the wear and tear.

If your home's insulation is more than 10–15 years old, or if your energy bills are climbing for no good reason, it might be time to take a look up there.

Need help figuring it out? American Insulation offers free attic inspections — no commitment, just peace of mind!