How Long Does Insulation Last?

Insulation is an essential part of any buildingís energy program. Having adequate insulation means that you save on utility bills like heating and cooling. However, like most parts of any property, insulation is prone to damage and can degrade over time.

So, how do you know when itís time to replace your insulation?

When to Replace Insulated by Material Lifespan

In theory, insulation can last up to 100 years under ideal conditions; however, it begins to degrade in as little as 15 when you factor in things like moisture and rodents. If your insulation sustains damage to the point where it doesnít provide the insulating value it should, itís time to replace it.

There are many factors that play into deciding whether or not you need to replace your insulation, but first, itís important to understand the lifespan of the most common insulation materials.

  1. Spray Foam Insulation

Spray foam insulation is one of the most popular types of insulation in newly-constructed buildings because itís air-tight, reliable, and durable. Because itís resistant to mold and doesnít absorb any moisture, it can last a lifetime and doesnít move unless it gets cut away. 

Unless your spray foam insulation gets disturbed by a construction-related project or animals, itís more than likely that youíll never have to replace or repair it during your lifetime.

Related: Spray Foam Insulation Costs in 2021

  1. Fiberglass Insulation

Fiberglass insulation is popular in many buildings because itís easy to install and cost-effective. Unless it gets damaged by moisture or mold, fiberglass insulation can last 80-100 years before you have to replace it. However, taking mold and moisture into account, the insulation can fail in as little as 15 years.

Moisture is the number one issue for fiberglass insulation; it needs to stay fluffy and light to perform its job properly. However, once it gets wet, it will absorb the moisture and need to be replaced regardless of its age.

Because it needs to stay light and fluffy to perform well, and itís common in attics, the insulation often gets compressed, losing its effectiveness and causing it to need to be replaced frequently.

  1. Cellulose Insulation

Cellulose insulation is gaining in popularity; itís an environmentally-friendly option thatís made from recycled materials. Itís also extremely effective at blocking air movement, even more so than fiberglass insulation. However, cellulose insulation has a short lifespan of 20 to 30 years, and it naturally starts to degrade about 15 years after installation.

Itís loose-fill insulation commonly used in attics, and itís also effective as secondary insulation when blown in over longer-lasting insulation like fiberglass. While it works well and is eco-friendly, you need to replace cellulose insulation up to 75% more often than other insulation types. Also, like fiberglass, itís prone to mold growth and moisture damage and has to get replaced the moment it gets wet.

  1. Mineral Wool Insulation

Mineral wool is a type of insulation that comes in batts, rolls, and blown-in varieties. This insulation can last anywhere from 30 to 80 years, depending on the material type (rock wool, slag wool, glass wool, etc.). Like other insulation (other than spray foam), mineral wool is prone to growing mold and holding moisture, and you will need to replace the insulation if it gets wet regardless of age.

Roof Damage & When to Replace Attic Insulation

replacing old foam insulation

When it comes to replacing attic insulation, it should last for the recommended length of 80 to 100 years as long as it doesnít suffer any damage and is installed with high-quality materials. However, over its lifetime, attic insulation commonly gets exposed to moisture or rodent damage, especially when a buildingís roof suffers storm damage or leaks.

So, how often do you need to replace attic insulation? In perfect conditions, it should last upwards of 80 years; however, it can become damaged and require replacement as quickly as 17 years after installation. At this point, the insulation can degrade or become damaged due to moisture, heat, animals, or damage during construction projects.

If your roof sustained storm damage or had a leak, any attic insulation that got wet will need to get replaced. The insulation can also get wet from condensation stemming from HVAC leaks, lack of airflow, or improperly vented bathroom fans.

Other issues, like rodent infestations, can also cause damage to the insulation. Squirrels and other rodents often seek shelter in attics and use insulation as warm bedding, leading to damage from them chewing on it, ripping it, and getting urine or feces on the insulation. If your insulation gets damaged by animals, youíll need to replace it immediately.

People can also inadvertently cause damage to attic insulation. Compressed insulation, which occurs when the insulation gets pressed together and renders it useless, is often caused by people storing their things in an attic, like boxes and storage bins. Many people will also lay down wood across the insulation to create a space to walk, which also compresses the insulation and diminishes its insulating properties.

So, attic insulation can last the full 80 to 100 years if left undisturbed by people and animals, and your roof doesnít suffer any leaks or storm damage. If it does get damaged in any way, you might have to replace the insulation as early as 15 years after you get it installed.

Do You Have to Remove Old Insulation To Install New Insulation?

So, if you need to replace your attic insulation, do you need to remove the old stuff first? Well, it depends.

If youíre simply replacing old insulation thatís at the end of its lifespan, you can install new insulation over the existing pieces as long as no moisture or mold is present. Before adding new insulation, youíll have to check the old insulation for mold and water. Moldy insulation looks like black streaks or spots. The old insulation should be 100% dry, or youíll have to rip it out before installing new insulation.

installing new insulation

For other areas, like crawl space and exterior wall insulation, youíll need to remove the old insulation before installing new pieces, whether itís damaged, moldy, wet, or not.

How about a free inspection and consultation of your roof? Get in touch with Advanced Consulting, and find out if your insulation is performing properly!

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