Spray Foam Insulation vs. Blown-In Cellulose

If you're considering an insulation upgrade, you may be weighing your options. You've heard good things about both spray foam and cellulose insulation. But which type of insulation will work best for you, your home, and your budget?

South Central Services has insulated hundreds of new and existing homes around Mechanicsburg, Pennsylvania. Our team uses both spray foam and blown-in cellulose for different insulation projects. Which insulation is best for your home will depend on several factors, but this article will make your decision easier.

By the time you’ve finished reading, you’ll understand:

• How versatile spray foam and blown-in cellulose are
• How well spray foam and blown-in cellulose can perform
• How long spray foam and blown-in cellulose last
• How expensive spray foam and blown-in cellulose are

Don't have time to read right now? Check out everything you need to know at a glance.

Spray Foam vs. Blown-In Cellulose: Insulation Versatility

One of the biggest factors in choosing an insulation is whether or not that product can be used for your project. Some insulations are incredibly versatile, while others are best suited for specific applications.

Let's examine the versatility of spray foam and blown-in cellulose insulation.

Spray Foam Can Be Used Anywhere In A Home.

Spray foam insulation is one of the most versatile materials on the market. Between the two types of spray foam insulation, open cell and closed cell, spray foam can be installed safely in any area of a home.

For basements, crawl spaces, and underslab foundations, closed cell spray foam insulation is the best version to choose. Places above ground in your home, like your exterior walls and attic, could have either closed or open cell spray foam.

No matter where you need insulation, spray foam is usually a reasonable solution. The only exception to this statement would be insulating existing exterior walls without removing drywall. Spray foam is meant for accessible applications.

Blown-In Cellulose Is Only Used In Attic Applications.

Compared to spray foam, blown-in cellulose is significantly less versatile. As a loose-fill product, blown-in cellulose can only be installed on the attic floor.

Despite not being used in walls, basements, or crawl spaces, cellulose is still popular for attics. Additionally, a different application of blown-in cellulose, called dense pack, is used to densely pack walls and rafters with the same product.

When we're talking about the blown-in application of cellulose, it is restricted to attic floors.

If your project is for somewhere other than your attic, you may want to consider dense pack cellulose. However, if you plan to reinsulate your attic, blown-in is a reasonable option.

Spray Foam vs. Blown-In Cellulose: Insulation Performance

It's good to know where insulation can be installed, but it's also essential to know how well it will perform. If you're investing in an insulation upgrade, you want to know that you're getting your money's worth.

So, how do the performance of spray foam and blown-in cellulose compare? Let's look in more detail.

Spray Foam Offers A High R-Value And An Airtight Seal.

Spray foam insulation is considered a premium product. Not only does spray foam deliver a high R-value, but it also offers an air-seal.

R-values vary by manufacturer. As a general rule, closed cell has an R-value of R-7 per inch and open cell has an R-value of 3.7 per inch. Depending on the application, spray foam can reach the necessary R-values for building codes with very little product.

For example, basement walls usually need no more than 2 inches of closed cell spray foam.

Spray foam creates an air barrier at approximately 1 inch of closed cell and 3.5 inches of open cell. This means that air cannot leak where the foam insulation has adhered. Traditional measures of insulation performance do not account for air-sealing. However, more modern building science has found that air-sealing makes homes more energy efficient.

Blown-In Cellulose Offers A High R-Value.

Blown-in cellulose insulation has a similar R-value efficiency to open cell spray foam. Blown-in cellulose should have an R-value of R-3.7 per inch when installed correctly.

Attics usually have higher R-value needs than walls, basements, and crawl spaces. No matter which insulation you choose for your attic, you'll need more inches to stop heat transfer effectively.

One feature that blown-in cellulose does not offer is an air-seal. Unlike spray foam, which adheres to the surface it is installed against, blown-in cellulose is simply loose particles. Air can easily pass through blown-in cellulose.

If you want to stop air leakage and the heat transfer that goes along with air leaks, you'll need to pair blown-in cellulose with a separate air-seal. There are lots of products available to provide an air-seal.

At South Central Services, we always pair cellulose with an air-seal. This maximizes the performance of the insulation. Without an air-seal, cellulose can only stop conductive heat transfer. While it does have a good R-value, modern building science indicates that homes need to be more airtight to be more energy efficient.

Spray Foam vs. Blown-In Cellulose: Insulation Longevity

If you're spending money on anything, you want to know how long your purchase will last. Some purchases aren't meant to last long, but insulation is expensive. No one wants their home to be constantly under construction.

So, how long can spray foam and blown-in cellulose last in your home?

Spray Foam Is A Permanent Insulation Solution.

Spray foam is meant to last for the lifetime of a structure. Since spray foam is spray-applied and adheres directly to the surrounding surfaces, spray foam shouldn't budge.

It takes a good amount of effort to disturb spray foam insulation. Left undisturbed and covered with appropriate coatings, spray foam should last indefinitely. Spray foam will not sag, settle, or gap.

Blown-In Cellulose Is A Long-Lasting Insulation Solution.

Blown-in cellulose does not adhere in place, but when installed correctly, it will last for an extended period of time. It is important not to disturb blown-in insulation to extend its longevity.

Left undisturbed, blown-in cellulose should last for 15 to 20 years. After a few decades, blown-in cellulose will start to settle. Settling will compromise R-value. The good news about blown-in insulation is that you can simply top it off to regain that R-value.

If not installed correctly, blown-in cellulose may never reach its expected R-value and will not deliver that R-value for 15 to 20 years.

Spray Foam vs. Blown-In Cellulose: Insulation Cost

One of the most critical factors in your insulation choice is what you can afford. Knowing how well different options perform is great, but ultimately, you have a budget to stick to.

How much do spray foam and blown-in cellulose cost? Let's look at the price tags associated with these insulation options.

Spray Foam Is A Premium Insulation With A High Investment Cost.

As we established earlier, spray foam is a premium insulation product. It delivers a high R-value and an airtight seal. It's meant to last as long as your home and can be installed anywhere.

All of these benefits and features come along with a higher price tag. Spray foam is one of the more expensive insulations on the market.

The cost of spray foam depends on several factors, but you can calculate a rough estimate using board feet.

A board foot is a three-dimensional measurement of a square foot: one foot high, one foot wide, and one inch deep. To find board feet from square footage, you multiply your square feet by the number of inches of spray foam you need.

At South Central Services, open cell costs between $0.25 and $0.75 per board foot, and closed cell costs between $1.15 and $1.75 per board foot. You can see sample calculations for attics, basements, crawl spaces, and pole buildings on our website.

It is a safe assumption that your project will cost several thousand dollars if you opt for spray foam.

Blown-In Cellulose Is A Budget-Friendly Insulation.

Compared to spray foam, blown-in cellulose is much more affordable. At South Central Services, blown-in costs anywhere between $1.50 to $4.00 per square foot. This price accounts for the separate air-seal we install on the attic floor.

The cost could be different if you work with a different company or install blown-in yourself. DIY insulation installation is less expensive up front, but there is always the risk of improper installation. If you hire a professional, discuss air-sealing with them to maximize the performance of your blown-in insulation.

The Bottom Line About Spray Foam And Blown-In Cellulose

In some ways, spray foam and blown-in cellulose are challenging to compare. Unless specifically examining insulation for the attic floor, spray foam and blown-in are like apples and oranges.

Generally speaking, blown-in cellulose is ideal for homeowners on a budget who want to upgrade their attic insulation. For anyone who wants insulation for their basement, crawl space, exterior walls, or pole building, another insulation may be better suited for you.

Now that you understand the differences between blown-in cellulose and spray foam, your next step is to:

• Discover if spray foam insulation can save money over time
• Estimate the cost of blown-in cellulose for your attic floor
• Compare blown-in cellulose to fiberglass batt insulation