Insulation. It’s what makes a house feel cozy. A well-insulated house shuts out even the most brutal South Dakota winter chill. If you’re considering improving your home’s coziness factor, reach out to SoDak Insulation for an inspection today.

You know that your attic needs insulation. But what is attic insulation? Let’s take a closer look at your house’s blanket.

The Language of Insulation

What is insulation? Insulation creates a barrier to keep heat in place. Just as a blanket on your bed keeps your body heat close to you, insulation in your attic keeps your house’s temperature warm in the living space of the home. Adding more blankets to your bed keeps your body warmer by containing more of your heat. Adding more insulation to your attic will help your home hold in heat as well.

Heat flowing from warmer spaces to colder spaces is called heat transfer. Insulation reduces heat transfer.

R-value is an abbreviation for resistance value. The term “R-value” describes how well a product contains heat. Insulation with an R-value of 5 will block more heat transfer than the same amount of insulation with an R-value of 2. 

Air sealing is one of the first steps when adding insulation. The installer will check your space for any drafts around windows, walls, or chimneys and seal any openings. Minimizing air movement will reduce heat transfer. It will also help to keep pests out.

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A vapor barrier keeps moisture and condensation on the warm side of insulation from moving to the cool side. In cold climates like South Dakota, the barrier should be between the living space and the attic insulation. 

Rafter vents are spacers that keep air flowing around the underside of the roof. They help keep your attic cooler in the summer. More importantly, they help prevent ice dams on your roof in the winter. 

Batts are single, solid pieces of insulation that are laid in place. Think of this like a long, skinny blanket roll. They are usually sold in rolls either 16 or 24 inches wide to fit perfectly between your rafters with no cutting. 

Loose-fill insulation consists of lots of small pieces that fill in gaps and irregular spaces. Installers apply this insulation by blowing it in with a machine. While it technically can be installed by hand, coverage is not as good, and the end result will be disappointing. 

Loose-fill is an excellent choice for filling in tight, hard to reach places. It’s an ideal choice for adding insulation to an existing structure. It can also be blown into walls through an access hole that can be patched after application.

How Does Attic Insulation Work?

Insulation works by holding air in place. Tiny pockets of air are held in place by the fluffy material. Because they aren’t mixing around, heat is not quickly jumping from one molecule to another, so it stays put longer. That’s why your big, puffy coat is so cozy in the winter. It’s also why the January wind on your face makes cold temps feel so much worse. All of that air rushing by moves more heat than you would lose otherwise.

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What Is Attic Insulation Made of?

Insulation can be made from lots of products. Here’s a rundown of the most common types.


Yes, it really is made of glass. Glass fibers are spun into a thick, fluffy material that looks a bit like cotton candy. Fiberglass is sometimes made of recycled glass, but not always, so check the label if that feature is a priority for you. Cover your skin thoroughly before manipulating fiberglass – any contact can irritate your skin. If you find yourself itching, taking a shower should take care of it.

Fiberglass has an R-value of 2.2 to 2.7 per inch if it’s blown in, and up to 4.3 in batts. It comes in different thicknesses, and you can layer one batt over another to reach your desired total R-value.


Cellulose is made of loose-fill, post-consumer recycled paper treated to be bug and fire retardant. Cellulose won’t irritate your skin. 

Cellulose has an R-value range of 3.2 – 3.8 per inch. This means that it doesn’t need to be as thick to achieve the total R-value you need. 

Cellulose is usually chemically treated to be waterproof. If it does get wet, water won’t absorb, but it may puddle and soak rafters. If you have prolonged moisture in your attic, mold could follow.

Mineral Wool

Mineral wool is made of rock fibers or slag from blast furnaces. It is sometimes called rock wool. 

Mineral wool comes in loose-fill or batts. Batts made from mineral wool are not very flexible and can be harder to work with. 

This material is naturally fire-resistant but more expensive than the others. It is partially made from post-consumer recycled material. Check the label for specifics. Mineral wool has an R-value of 3 to 3.3. 


Easily the most environmentally friendly option, cotton attic insulation is made from denim jeans. The manufacturer shreds industrial scrap and post-consumer denim to make batts that are as soft and skin-friendly as your own wardrobe. 

Cotton insulation is treated with a non-toxic solution to make it pest- and fire-resistant. With no chemical or respiratory contaminants, this is a health-conscious choice for anyone with chemical sensitivity. 

Cotton insulation will cost 15-20% more than fiberglass, on average. It has an R-value of 3.7-3.8 per inch.

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The More You Know

You can make your house a coziness fortress with the right insulation. Consider what kind of attic insulation is best suited to your needs and budget. If you have noticed your utility bills creeping higher and higher, or the temperature is getting harder and harder to control, you might need more attic insulation.

Contact SoDak insulation today to get a free inspection, and you’ll be as toasty as hot cocoa next winter.

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