How Long Does Fiberglass Insulation Last: What to Know about the Insulation

You may rely on fiberglass as your home insulation choice, but how long does fiberglass insulation last? It’s best not to take guesses about insulation, especially for energy efficiency.

You want to protect your house while keeping the energy bills down, and understanding the longevity of your type of insulation, such as fiberglass or spray foam insulation, is crucial.

But you won’t be able to achieve energy savings if your insulation doesn’t work as expected. So, aside from paying detailed attention to your insulation, whether attic insulation or spray foam insulation, you should also understand its condition and care. Proper insulation removal and replacement are essential to maintain its effectiveness.

How Long Does Fiberglass Insulation Last?

Is fiberglass insulation durable? To answer that question, you should know that fiberglass, often used in loose fill and batt insulation, is made from fiber and glass. This kind of fiber, made from glass, is applied for many applications and usages, including in-home insulations, where it provides energy efficiency and longevity under ideal conditions.

This tough and durable material is used in home improvement projects, but you can also find it in other products, like tent poles, shower curtains, roofing products, and car parts.

how long does fiberglass insulation last

Read also: How Long Does Attic Insulation Last?

Rumor has it that fiberglass can last a lifetime. Generally, it can last at least 80 years and up to 100 years, especially under ideal conditions. However, you should know that nothing lasts forever, and it also applies to fiberglass. Over time, factors like air movement and moisture can make insulation go bad, necessitating replacement.

Fiberglass and cellulose insulation will deteriorate over time, no matter how tough and sturdy it is. The condition worsens when some elements or factors interfere with the material’s longevity, such as moisture or improper installation.

Read also: Comparison Between Fiberglass VS Cellulose Blown Insulation

When to Check the Insulation

Before you wonder how long fiberglass insulation lasts, you should also check the insulation if you spot these signs:

  • You see water damage, typically resulting from burst pipes or roof leak
  • Mold growth. It usually happens as the result of the air leaks
  • Dirt and debris
  • Puncture or damage
  • Wind washing
  • Rodent, insect, and other possible pest activities

Moreover, you should know that your utility bill is increasing significantly. This may be caused by poor insulation that has lost its effectiveness. It also means you must replace the old insulation with a new one.

In short, you should always be cautious and aware of the situation. When there is something off, immediately check for any sign of trouble. You may be able to save a lot of money if you detect the possibility of issues earlier.  

What Are the Disadvantages of Using Fiberglass Insulation?

Fiberglass does have its own perks, such as its eco-friendly nature, flexibility, and noise-canceling effectiveness. However, you should also be prepared for the downsides.

  • Coverage. Fiberglass usually comes in pre-cut panels, which can be difficult regarding coverage. You will have to struggle with crannies or odd shapes for the installation.
  • Moisture. Fiberglass has good fire retardant quality, but when it comes to moisture, it’s not impressive. Fiberglass isn’t an effective moisture-repellent material. It is prone to mildew and mold.
  • Air exchange. Fiberglass isn’t as dense as other materials, making it ineffective when dealing with air leaks. You need to figure out a way to have the airtight seal.
  • Mold. Fiberglass can soak up moisture, which creates a perfect breeding environment for spores. When it happens, you need to replace it right away because it will compromise the overall structure of the insulation.

How Often Should Insulation Be Replaced?

People may have different opinions about how often the insulation should be replaced. Some people may say a decade would be an ideal time, while others say two decades will be the right option. Generally, 15 to 20 years would be the ideal time to do the replacement.

However, this time window doesn’t apply when there is damage to the insulation. If the insulation has somewhat been compromised, you must replace it immediately.


In the end, ensure the insulation is intact and functions well. You seriously don’t want to compromise the entire structure and your family’s safety. Now that you already know the answer to how long does fiberglass insulation last, you can make the right decision.

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Insulator is a skilled author and Insulation expert with years of experience in the field. He has authored several articles and books on various aspects of insulation installation, maintenance, and repair.