How Long Does Attic Insulation Last? Is It Worthy to Replace It Every Few Years?

How long does attic insulation last? It depends on what material you are using as the insulation in your attic. Different insulation materials will offer you a different lifespan. So, if you are curious about it, make sure to check the lifespan insulation material you are using in this article below.

How Long Does Blown-in Attic Insulation Last?

You may wonder what blown-in attic insulation is. According to sources, blown-in attic insulation is several types of insulation which refers to any insulation type which is thick, lumpy, and dense. These types of attic insulation will include fiberglass, cellulose, and other materials with such features (thick, lumpy, and dense).

How long does attic insulation last, especially when the type of attic insulation used is blown-in? Well, the lifespan of such insulation will depend on the material itself. Let’s check the explanation for more detailed information.

how long does attic insulation last

As mentioned, blown-in insulation will include cellulose and fiberglass. Other materials of insulation that are also blown in are available, but these two are the most common ones.

What is the lifespan of cellulose insulation material? According to sources, you can expect cellulose insulation to have 20-30 years. However, this material is said to start degrading after 15 years of installation.

Note that the insulation material will also be easily worn out if faced with extreme weather conditions. With such instability, you cannot expect cellulose as the first line in terms of attic insulation. That’s why people are only expecting it to be supplementary insulation.

How Long Does Fiberglass Insulation Last in Attic?

What about fiberglass insulation? Compared to cellulose, fiberglass insulation is way better. Why so? Despite its low cost, fiberglass insulation can provide you with a long-term 80-100 years of insulation effect. Unless it’s damaged, the long-term insulating effect should persist.

Unfortunately, some fiberglass insulation may start falling in quality after it reaches 15 years post-installation. Therefore, it is advised that you inspect this once the insulation reaches 10 years of age.

Is fiberglass better?

So, does it mean fiberglass insulation is way better compared to cellulose insulation? Yes, especially in terms of its durability. Do acknowledge that cellulose is made from organic material. This, when exposed to moisture, may become an excellent energy bar for mildew, termites, or other organisms.

To make your knowledge complete, let’s learn the pros and cons of cellulose insulation and fiberglass insulation below.

Fiberglass insulation


  • It can be installed in the form of batts or blown in.
  • It’s cost-effective, especially when compared to spray foam.
  • When used as thermal insulation, fiberglass is one of the greatest options.
  • It lasts long since it isn’t made from organic products–hence it doesn’t promote mildew infestation.
  • That said, it often comes with a lifetime warranty.
  • You can choose various R-values from the ones offered in the market.
  • It’s not flammable.


  • It is still less effective in terms of thermal insulation.
  • Its particles may endanger your health as they are carcinogens–although not all fiberglass insulation has these carcinogen materials.

Cellulose insulation


  • Itch-free insulation material
  • It is made from recycled magazines, newspapers, cardboard, and other kinds of paper.
  • Fire retardant as well.
  • It is not chewable by insects, despite being a green insulation material.
  • Quite effective in insulating your attic.
  • It may also help your house to become soundproof.


  • It’s prone to sagging
  • It is added by many chemicals to promote its fire-retardant feature.
  • It makes a lot of dust during installation, which may disturb you if you are a clean geek.

Is it worth the bucks to replace insulation?

So, is replacing insulation worth it? Unless your insulation has already been damaged, then it’s a bit spendthrift to replace your insulation once every few years. Most insulation materials offer a lengthy lifespan. So, make sure to know how long does attic insulation last before setting the decision to purchase it.

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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.