How Long Does Blown-In Insulation Last?

Insulating a home is both a significant expense and a difficult undertaking, so it's natural to want to know how long your investment will endure before needing to be replaced. Or, you could be wondering if your old insulation is nearing the end of its usefulness. So when it comes to blown-in insulation, how long will it last? We've done the research to answer this question.

Blown-in insulation is produced with cellulose, fiberglass, or mineral wool. The life expectancy varies between these three materials.

  • Cellulose blown-in insulation may last 20-30 years.
  • Fiberglass blown-in insulation may last 80-100 years.
  • Mineral wool blown-in insulation may last 30-80 years.

Now that we've answered your initial question, you may have others. You may be wondering what the differences are between these types of insulation materials, or you could have other inquiries about your existing insulation. Keep reading to learn more!

Worker spraying blow-in insulation to the attic floor joist, How Long Does Blown-In Insulation Last?

We have done so much research on this, that we have a series of articles on the topic! If you're interested in other types of insulation too, check out this article about how long insulation can last in your home.

Types Of Blown-In Insulation And How Long They Last

Here we will discuss the different types of blown-in insulation in greater detail and add to our explanation of their lifespans. This will give you a better idea of why some of these materials last longer than others. We will also tell you what to expect from each substance in standards of performance.

A hose spraying blow-in insulation to the attic flooring


Cellulose blown-in insulation has risen in popularity in recent years due to the fact that it's sustainable. It is created from plant materials—mainly recycled newsprint and cardboard.

Cellulose was first introduced to the world in the 1700s, and it could have been a popular material among the elite of the time. Thomas Jefferson is known to have insulated his home with it in 1772.

However, it did not gain widespread approval until the 1950s. This is when fire retardant materials were added to prevent combustibility. Nowadays, homeowners invest in this material for a variety of reasons.

The greatest of these is perhaps the fact that it's environmentally friendly. It's not only produced from recycled materials but the manufacturing process also requires very little energy, few chemicals, and emits no greenhouse gases.

As for performance, cellulose is incredibly functional as an insulator. Its R-value, the measure of heat resistance, is exceptionally high. It is better at preventing the transfer of heat energy than both fiberglass and foam.

Furthermore, this material is safe and promotes health. Due to additives such as ammonium sulfate and boric acid, it is both fire resistant and unwelcoming to pests and bacteria. Homeowners don't have to worry about the buildup of mold that can make their families sick with this material.

There are some drawbacks, though. First, this material lasts far shorter a time than foam or fiberglass—only 20-30 years. This is partly due to the material being very heavy. It will begin "settling" far sooner than foam or fiberglass, as they are lighter. Over time, this will end its functionality and promote deterioration.

Cellulose is also prone to absorbing moisture. This could potentially be a huge problem for the homeowner and negate cellulose's other great qualities. The absorbed water may break down the chemical additives, rendering them useless.


Now let's move on to fiberglass blown-in insulation. Fiberglass is created from plastic reinforced by microscopic glass fibers. These fibers, though tiny, are useful at preventing the movement of heat.

Fiberglass was first invented in the late 1800s but did not come into use as an insulation material for homes until the 1930s. This is when the company Owens Corning debuted its first insulation product.

Fiberglass remains a very popular choice for homeowners, and there are a few very good reasons for this. One of these is that fiberglass is cost effective.

The price of fiberglass is solidly in the economy category, and since it is expected to last 80-100 years, this means that it will truly be a solid investment. Not to mention that the time and energy used to install the product will also not be a waste.

To continue, fiberglass resists both moisture and heat. Because the basic ingredients are plastic and glass, it is generally impermeable by water. It also will not burn.

Fiberglass is unattractive to pests, and it is light enough that it settles slowly. This contributes to its long life expectancy.

Still, there are a couple of drawbacks to consider. Even though it may happen more slowly than cellulose, fiberglass does tend to settle, so homeowners may have to reinforce it every so often for best performance.

While fiberglass will not absorb water and will quickly and easily dry out if it is exposed to a leak, if it is placed without venting, the water could make its way in between the fibers and build up. This would keep the insulation from functioning properly, as water is a conductor for heat energy.

Mineral Wool

Mineral wool is produced with plastic bound by fibers of either rock or iron ore. An American chemical engineer by the name of Charles Corydon Hall invented mineral wool in the late 1800s, but it wasn't fabricated as insulation until the 1930s.

Mineral wool has become sought after as a thermal insulator and soundproofing agent. Here are a few thoughts as to why.

One of the greatest of these is that mineral wool is impermeable to moisture and is unaffected by water leaks. It is still functional as an insulator even if it gets wet.

Another advantage to consider is that mineral wool is not only useful to prevent the movement of heat but it's also useful at soundproofing a home. Due to its porous quality, it is better than other types of insulation materials at absorbing sound.

It also acts as a fire barrier, especially when installed inside walls. Since it is created with inorganic materials, it won't burn until heated to extreme temperatures. It will prevent a house fire from moving freely about a home.

Mineral wool, however, could be on the shorter side of lifespans. This is especially true of slag wool, which is produced with fibers of iron ore. Slag wool may land on the shorter end of these lifespans, around 30 years, while rock wool will last longer.

Does Blown-In Insulation Deteriorate Over Time?

Insulation specialist spraying blow-in insulation in the floor joist

While fiberglass insulation will deteriorate in its functionality, cellulose blown-in insulation is the only type that will naturally degrade over time. This is due to the sustainability of the product since it is created with plant materials. For some, this is actually seen as an advantage.

Removing Blown-In Insulation

Knowing when and how to remove your blown-in insulation is necessary to ensure a comfortable, safe, and cost-effective home. We will answer some of the most frequently asked questions on this subject.

Should I Remove Old Blown-In Insulation?

Deciding whether blown-in insulation needs to be moved can be tricky, especially when the lifespan of a product can vary so greatly. So here are a few situations in which it would be best to remove the old insulation.

One of these is when you will be changing to a different type of insulation. It's preferable not to layer different types of insulation.

Another is if the insulation has been damaged by an infestation or water. In either of these scenarios, the insulation should always be removed.

A final question is whether the new insulation you plan to install will have room. If there is no space for the new insulation, then you should remove part or all of the existing insulation.

How Do You Remove Old Blown-In Insulation?

Blow-in insulation in the floor joist of a house

Once you've determined that the insulation does in fact need to be removed, you will surely want to get this part of your project done as soon as possible. Before beginning, you will need to ensure that you have all the supplies needed, including protective gear.

Take a look at these safety goggles on Amazon.

Suit up in a long sleeve shirt and pants to protect your skin, a mask, gloves, and goggles. As for supplies, you will need garbage bags and a wet/dry vacuum.

Suck the insulation into the vacuum, and as often as needed, stop to remove the insulation from the vacuum and place it into the garbage bags. To speed up the process, you may consider buying or renting a HEPA vacuum which will automatically transfer the insulation to the bags, saving you a step.

Take a look at this HEPA wet/dry vacuum on Amazon.

Can You Reuse Blown-In Insulation?

When it comes to fiberglass and cellulose insulation, this is a possibility. However, it should only be done when being handled by a professional to ensure that the materials are not damaged or compromised for further use.

Spraying blow-in insulation to the floor joist of the ceiling

Is It Worth Replacing Attic Insulation?

Blow-in insulation in the ceiling

Yes! There are many advantages to insulating your attic after removing old material. This can be helpful to the homeowner by:

  • Keeping energy bills low.
  • Acting as a sound barrier to outdoor noises.
  • Making the home more comfortable both in cool and hot seasons.
  • Acting as a moisture barrier in case of a roof leak.
  • Adding to the home's value.
  • Deterring pests.
  • Making the attic usable as a living space.
  • Preventing structural damage caused by ice.
  • Adding to the HVAC system's lifespan.

In Closing

Worker spraying blow-in insulation to the attic floor joist

Before reading this post, you perhaps may have been confused about how long your existing blown-in insulation was expected to last, or you may have been questioning the lifespan of blown-in products on the market.

We've concluded that cellulose insulation will last the shortest period of time, 20-30 years, while fiberglass will last the longest, even up to 100 years. We hope that this has given you a better understanding of these materials and aided you in your home project.

Want to learn more about insulation? Visit these related posts:

Is Blown-In Insulation Cheaper Than Rolls?

How Long Does Fiberglass Insulation Last?

Share this article

Leave a Reply

Your email address will not be published. Required fields are marked *