What Is The Best Insulation For Attics?

Attic insulation is responsible for keeping your house cool in the summer and warm in the winter. Simply put, attic insulation is the most significant protective layer that shields your home from the outside climate. As such, it's critical to choose the right type to have the best long term return on investment. But what is the best attic insulation? For your convenience, we did the research to bring you the answer.

There are numerous types of attic insulation, and each has its respective pros and cons. However, spray foam insulation is the best choice for attics because it can expand into small spaces providing an airtight seal, it's waterproof, and it lasts longer than other types of insulation.

If you still have some lingering questions about attic insulation, don't fret. In this guide, we'll explore the topic in greater detail, and we'll answer some additional questions you might have. Just keep reading!

An insulation specialist with PPE on spraying foam insulation on the attic of the house, What Is The Best Insulation For Attics?

Why Spray Foam Insulation Is Best For Attics

As mentioned, spray foam insulation is by far the superior option for attics. To give you a better idea of what makes foam insulation so amazing, we'll discuss its many benefits at length below.

R-Value (Insulating Efficiency)

To understand the effectiveness of different types of insulation, it's important to understand R-value. R-value is a measurement of an insulation's ability to prevent the flow of heat into and out of a house. The R-value of insulation is measured per inch of insulation. In other words, if you opt for a type of insulation with a lower R-value, you'll have to use a thicker layering of it, and vice versa. The bottom line is that a higher R-value means better insulation efficiency and thus a lower energy bill.

Foam insulation has an R-value of approximately 3.5 per inch, but this value can change depending on the specific type of foam insulation. This R-value is higher than most of the other types of insulation, making it the ideal choice for better climate control.

Airtight Sealing

One of the characteristics of spray foam insulation that makes it particularly advantageous is that it's airtight. Once foam insulation is sprayed in an attic, it creates an airtight seal that makes it an even better insulator. An airtight seal is important because it can help prevent moisture and unwanted critters from getting into the attic. Other types of insulation, like fiberglass rolls, for example, don't provide this airtight seal.


Another characteristic that makes spray foam the best choice for attic insulation is that once installed, it's waterproof. The pitfall of many types of attic insulation is that, once it's wet, it becomes significantly less effective. What's more, wet insulation will lead to mold and mildew growth which can cause more problems down the road.

Spray foam insulation is impermeable to water, so you won't have to worry about it getting moldy if it's exposed to water.


Spray foam insulation doesn't deteriorate with time (as is the case with many other types of insulation). Thus, when installed properly, you can expect spray foam insulation to last for the life of the home.

Other types of insulation might require occasional maintenance (or complete replacement for that matter), but this isn't the case with spray foam insulation. This makes spray foam insulation the ideal choice for homeowners looking for a low-maintenance insulation option that will continue to provide excellent insulation for decades.

Greater Structural Strength

In addition to providing top-notch insulation, spray foam will also give the home greater structural strength. As mentioned, spray foam is unique in that it expands to fill the surrounding nooks and crannies. This will bolster the roof and provide added strength.


At this point, you might be thinking that the cost to insulate an attic with spray foam insulation must be exorbitant. But the fact of the matter is that the cost of spray foam insulation is in the same ballpark as the other types of insulation. Thus, given all of its benefits, spray foam insulation is an excellent value.

How Much Of A Difference Does Attic Insulation Make?

If you're considering adding insulation in your attic, you might be skeptical about how big of a difference it actually makes.

In reality, attic insulation is the best protection from the harsh summer heat and bitter winter cold. Attic insulation will make a notable difference in your energy bill (more on that later), and you'll be able to feel its benefits first hand. Insulating your attic is by far the best way to make your house more energy-efficient.

How Long Does Attic Insulation Last?

The lifespan of attic insulation varies depending on the particular type of insulation in question. To keep things simple, we'll list the average life expectancy of some common types of insulation.

  • Fiberglass: 80+ years
  • Cellulose: 15 to 30 years
  • Spray foam: 80+ years
  • Mineral wool: 100+ years

The bottom line is that most types of modern insulation have a very long lifespan; some will just require maintenance and attention periodically.

There are, however, several factors that affect the lifespan of insulation. The lifespan of insulation might be adversely affected if:

  • The roof has had water damage
  • It has been damaged by rodents or other animals that have made their way into the attic
  • The home has experienced a fire or natural disaster

If any of the aforementioned scenarios apply to you, the lifespan of your insulation might have been adversely affected.

How Much Money Will Insulating My Attic Save Me?

Insulating your attic is one of the best things you can do to decrease your energy bill. The cost savings from insulating your attic will depend on a number of factors, but you can generally expect to save anywhere from $500 to $600 each year by properly insulating your attic.

Results may vary, but rest assured that properly insulating your attic will give you a long term return on investment; considering that the average insulation job costs between $1,700 and $2,100, you could start to see a return on investment in as little as three years.

Can You Put Too Much Insulation In Your Attic?

Now that we've talked at length about the benefits of attic insulation, you might be chomping at the bit to put as much as you can in your attic. But before you do, a word of caution—it is in fact possible to put too much insulation in your attic, and doing so can prevent the attic from ventilating properly.

If you get too insulation-happy you run the risk of blocking vents that are critical to your home's ventilation. To ensure that your attic doesn't have too much insulation, thoroughly inspect the area to make sure that the vents in the attic aren't obstructed by the insulation material.

As long as your vents are unobstructed, you need not worry about putting too much insulation in the attic. If the attic can still ventilate properly, there aren't necessarily any ill effects of over insulating aside from the cost to do so.

In Closing

We hope this guide has helped you better understand how spray foam insulation can save you money by making your house more energy-efficient. Before you go, be sure to check out this other post that might be of interest:

How Often Should You Air Out Your House?

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