How Long Does Insulation Last And When To Replace It

When energy bills are rising, you feel it's getting harder to maintain temperatures in your home. It's time to consider replacing your insulation. One aspect that many would look for is longevity. How long does insulation last? And, when should you consider replacing it? If that's what you're wondering, let's find out!

Depending on the type of insulation, it can last anywhere between 20-100 years. Some will require inspection sooner. Others will only need replacement if there are signs of damage or leaks. Here's a list of how long each type of insulation will last:

  • Spray foam insulation: the lifetime of your home
  • Mineral wool: lasts the lifetime of your home
  • Fiberglass: 80 years
  • Cellulose: 20-30 years

The list above is a general idea of how long insulation should last in perfect conditions. This is great if you're carrying out a home energy audit inspecting existing insulation or planning new insulation for your home.

Of course, it's nearly impossible to keep things consistent. Some accidents out of your control can happen. In these situations, it might cause a need for a replacement sooner! If you'd like to learn more, keep reading ahead.

A fully suited Hvac personnel spraying foam insulation on the walls, How Long Does Insulation Last And When To Replace It

The Types Of Insulation and Lifespan

As mentioned above, how long your home insulation lasts depends on the type or types you choose to install. Some instances can shorten the lifespan. The issues can come from installation or other factors out of your control - like a water leak.

Let's go over the four main types of insulation.

Spray Foam Insulation

Spraying foam insulation in the between the wooden framing of the house

Spray foam insulation is rated to last as long as your home stands. But why does it last that long? It's made of an inert polymer that does not rot. Additionally, it's also mold and water-resistant. Some claim it can prevent the future growth of mold because it creates airtight seals.

Since spray foam covers areas well, it cuts off the air and water supply that mold needs to grow. It has resistance to many factors that would typically reduce the lifespan of other insulation types. Still, some situations will warrant the reinstallation of spray foam.

How well spray foam holds up will depend on the quality of the job from installers. There are a few noticeable signs of poor application. The most notable one would be a foul odor. Some would describe the smell as fishy.

If you notice this odor, it means the foam ratio is off-balance. Consequently, an off-balance ratio will not allow the foam to cure correctly. Along with these issues, the spray foam will allow air leaks - resulting in inadequate insulation.

Thus, spray foam should last the lifetime of your home if you have reputable spray foam installers do the job correctly. If you'd like to learn more about the odor spray foam can emit, check out our post, " How Long Does Spray Foam Insulation Smell?"

Mineral Wool

Installing the fiberglass insulation in the roof attic

Mineral wool is another insulation material that should last as long as your home stands. It is made of basalt and recycled slag. These two materials are melted and then spun into fiber batts.

The reason mineral wool insulation lasts a long while is because of the many beneficial properties it holds. It's hydrophobic, meaning it's water-resistant. Additionally, it has a high melting point, making it a highly fire-resistant material.

Basalt and steel slag are inorganic materials. Given its water-resistant qualities, it does not promote mold growth. So, it gives mold no sources of food.

While it might seem nearly indestructible, some situations will cut its lifespan. Mineral wool will only work well if there's no physical damage present. So, if your area has a critter problem, you might have to replace mineral wool sooner than expected.


Pink fiberglass insulation in the attic


Like the two previous insulation materials, fiberglass can last anywhere between 80 years to your home's lifetime. However, this timeframe only applies if you can consistently provide the perfect conditions for the material to excel.

Whether in batt insulation or rolls, fiberglass insulation has a similar lifespan.

Issues like water damage and mold growth are some factors that can cut fiberglass insulation's lifespan. If it is wet for too long, you won't prevent mold growth on the surrounding area and the inside of the fiberglass.

Additionally, fiberglass allows high amounts of air to pass through. Under the right conditions, it might even filter out food sources for mold. As a result, you get mold growth within the insulation material. Thus, you'll need to replace it sooner.

Lastly, physical damage will also shorten its lifespan. Whether accidental damage or damage from critters, fiberglass will lose its insulation properties.

If you have a rodent/pest problem - and it's getting harder to maintain temperatures - you might want to make sure there aren't any critters using the insulation as nesting material.

Cellulose (Blown Insulation)

Cellulose insulation photographed up close

The insulation material with the shortest lifespan is cellulose. It will last around 20-30 years under ideal conditions.

Cellulose doesn't last as long because it lacks the many properties that the others offer. Cellulose isn't as water-resistant as the previous three insulation materials. Since it's made of recycled paper products, it will not handle water damage well.

Additionally, some suggest 90% of the insulation material will not survive a mold infestation. Lastly, cellulose does settle over time. It can settle as much as 20%. Of course, you can solve this problem by having more cellulose blown in.

Nevertheless, things don't always go as planned. If you face a water leak near your cellulose insulation, it can settle faster. Meaning you're more likely to consider replacing it after 10-15 years.

When To Replace Insulation

Now we know the lifespan of multiple insulation materials. Of course, many factors can shorten that period. Still, accidents aren't a daily occurrence. So, if your insulation has worked well for decades, there are still some signs that can indicate it's time to look for replacements.

Always consider both walls and roof insulation.

The first sign to consider is temperature. How well is your home maintaining a comfortable level? In addition, are there areas in your home that seem colder or hotter than others?

Humidity is another factor to keep in mind. Excess moisture can sometimes affect how long insulation lasts. This is especially true if your home suffered water damage.

Another factor to take into consideration is the performance of your HVAC system. If it's working harder to maintain temperatures, it will show up with higher energy bills.

People with allergies or respiratory problems might also suffer from frequent allergy problems and illnesses. If you suspect you're suffering from temperature loss, get an energy audit.

How Do You Tell if Your House Is Well Insulated?

There are a few easy ways to tell if your home is well insulated. The first would be temperature drops. If you turn off your heater and your home manages to retain the same temperature, it means the insulation is keeping warm air.

On the other hand, if your home quickly gets cold after turning off the heat, it indicates you're losing heat quickly. Thus, your home is not well insulated.

One test you can apply to your home is a touch test. On a cold day, touch the walls and floors. If it's warm and dry, your insulation is not allowing air to escape quickly.

The other test you can perform is a room check. If some rooms are colder/hotter than others, your home isn't well insulated. However, if you're comfortable in any room, the insulation did its job.

Where Is Most Heat Lost From a House?

Since not all houses are the same, the area that loses the most heat will depend on the construction of your home. You'll need an energy audit to identify your most problematic areas.

If you still want a general idea of where the most heat loss occurs during the winter, the most problematic areas will be windows, doors, and walls. As some suggest, they account for 38% of heat loss during the winters.

Roof insulation is the next suspect, especially during summer when roofs and attics accumulate heat from the sun. Old attic insulation and even loft insulation may need replacing if your top house level gets too hot during summertime.

How Much Does It Cost To Remove and Replace Insulation?

A fully suited insulation specialist spraying foam insulation of the ceiling

Check locally for the costs of insulation replacement. Whatever insulation product you're using, replacing a foam board or even loose-fill fiberglass could still be cheaper when you consider energy saving.

The size of your home and the type of insulation you choose to replace your current material will influence how much you pay out of pocket. Here's a list of prices between the three insulation types:

  • Spray foam - $2-$5 per square foot
  • Batt (fiberglass/mineral wool) - $2-$4 per square foot
  • Loose-fill (cellulose) - $2-$5 per square foot
  • Blown-in (cellulose) - $1-$4 per square foot

As some suggest, the average cost of insulation removal is $305 or $1 per square foot.

Is It Worth Replacing Old Insulation?

Replacing old insulation will depend on your tolerance. If you're still comfortable in your home, there's no need to replace it just yet. However, if some areas feel unbearable to stay in, replacing insulation could be worthwhile.

The same could be said for energy bills. If you're not comfortable with the rising costs, new insulation will help put an end to it. Though, one aspect you want to avoid is condensation.

Improving air quality in your home is always a worthwhile investment! Frequent problems with condensation will be a strong indicator for replacing your old insulation material. In this sense, it's worth the cost to get new insulation installed. This way, you can prevent mold problems that come along with condensation.

Final Takeaway

A fully suited Hvac personnel spraying foam insulation on the walls

We hope you found the information above helpful! When it's time to make changes in your home, it's not going to be easy. You have to make decisions that will require some research to ensure you get the results you want.

Before you go, do you need more information on the insulation types? If you're considering going with polyurethane insulation, you might be curious to know if it degrades. Check out our post, " Does Polyurethane Insulation Degrade?"

Share this article

Leave a Reply

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