Types of Insulation

The main types of insulation are: fiberglass, cellulose, and foam. Each type has its pros and cons.

Fiberglass Insulation

Fiberglass has been around the longer than other modern insulation options. It's easy to work with and highly available for purchase.

Fiberglass insulation comes in three main forms:

• Rolls - These are made from a blanket of insulation, which is rolled up for easier transportation. The advantage of using a roll is customization. A contractor can cut it into any length, depending on the needs of the area.
• Batts - A "batt" is a rectangular sheet of blanket insulation. They come in pre-sized tiles so they are convenient to use when insulating standard 2x4 or 2x6 framework. They are sized just right to slip in between the studs.
• Loose Fill or Blown - This type is more like a loose stuffing that can be blown into an area that needs a lot of insulation. Loose fill insulation is mainly meant for attics, where insulation is crucial. Because deep amounts are needed, it's more effective to blow insulation into thick piles using a special machine, rather than stacking up countless layers of blanket insulation.

Fiberglass insulation is sometimes referred to as glass wool because of its fluffy consistency. Some people wonder if fiberglass is actually glass. Yes, it's definitely glass.

It's made by heating glass to extremely hot temperatures until it is melted. (Much of the glass is recycled from old bottles and windows.) Once the glass has been heated into liquid form, it is dropped into a mechanism called a "fiberizer." The fiberizer is a spinning bowl with many small holes in it. As the hot liquid glass drops into the bowl, the centrifugal forces push the glass through the tiny holes. The resulting pieces of glass are so small that they are light and fluffy. This process is basically the same thing as spinning cotton candy.

One of these is fiberglass, and the other is cotton candy. If you care about your health, don't eat either one of them.

Now we answer the burning question: Why is insulation pink? Because after the glass has been fluffed into small fibers, it is sprayed with a pink polymer glue to hold it together. The color makes it easier to gauge how much glue has been applied. It does come in a variety of colors, because companies can use whatever color of glue they'd like.

After the fiberglass is glued, it is sprayed onto a conveyor belt, where it is heated (to dry the glue) and slightly compressed into nice sheets.

Cellulose Insulation

Cellulose is made from recycled paper, which introduces 3 challenges:

• Flammability - Obviously paper is quite flammable, so modern cellulose insulation must be treated with fire retardant chemicals, like boric acid and ammonium sulfate.
• Mold - Paper has a tendency to absorb moisture, which makes it a risk for mold. A mold retardant chemical is added to prevent this.
• Pests - What's to stop insects from eating up the paper? Well, they have a chemical for that too.

Cellulose insulation was first used as far back as the 1950s. It was introduced into the US during the 1970s, but spent a couple decades struggling to gain widespread adoption due to concerns over flammability. Fortunately, years of experience has made cellulose a much more practical option. As long as proper chemical additives are used, the three main challenges of cellulose are addressed.

One of the main challenges with cellulose is that it's more of a process to install. It doesn't come in blanket style insulation, like fiberglass, so it always requires a blower machine.

The three main forms of cellulose insulation are:

• Loose Fill - This works just like blown fiberglass. The same type of machine can be used.
• Dense Pack - This involves packing insulation tightly between studs. A plastic barrier is placed over the studs, and a hole is cut near the bottom. The blower nozzle is placed in the hole, and insulation is blown in for several minutes per section. Eventually it forms a densley packed pillow of insulation, providing great R value. This can be time consuming.
• Wet Spray - The insulation is moistened first, allowing it to stick to the surface its applied to. This is very messy, but being able to insulate the ceiling from a distance can also be a time saver.

Foam Insulation

Foam insulation comes in a few different forms:

• Open Cell Spray Foam - This sprays in wet, and then hardens. It's fairly soft, and doesn't produce a perfect moisture barrier, but it costs less than closed cell spray foam.
• Closed Cell Spray Foam - This sprays in like open cell foam, but it dries into a more dense surface. This makes it a better barrier for air and water.
• Rigid Foam Board - This is just what it sounds like. It's a foam panel that can be installed over unfinished walls, like on a foundation in a basement.

Applying spray foam is a lot like painting a car. While wearing full-body protective gear, you spray it across the entire surface. After it applies, you get to watch everyone's favorite part as it then expands and fills the space. You may need to go back and fill in any low spots, but practice makes perfect.

Fiberglass vs Cellulose Vs Foam Insulation - The Showdown

Cost - Fiberglass is the most affordable. Cellulose is slightly more expensive, and foam can get pricey.

Air Penetration - Foam is the best at preventing air flow, with cellulose in a close second place, and fiberglass performing quite poorly.

R Value - Closed-cell spray foam is the clear winner in this category, with an R Value of R6+. Compare this to fiberglass batts and blown cellulose, which sit around R3 - R3.5.

Vapor Resistance - Moisture resistance is closely related to air flow resistance, because the movement of air is what carries moisture into the insulation. Because closed-cell spray foam resists air travel, it leads in the vapor resistance category. Cellulose follows right behind, and fiberglass is dead last, because it requires extra measures to block moisture from entering.

Health Risk - During installation, each kind of insulation has its own health risks. Focusing on post-installation, fiberglass is the safest, as it does not have the off-gassing issues found in cellulose or foam.

Flammability - Modern insulation is all fairly fire-resistant. Cellulose, if treated with proper fire retardants, seems to be the most resistant in tests and demonstrations. However, it's hard to name a single winner here, because there are many types of foam, some of which are quite resistant to fire, and others not as much. All types will burn to some extent, and all decent types stop burning when no longer exposed to direct flames.

Ease of Use - Usability is subjective, but given that fiberglass can be installed by any DIYer, it takes the win in this round. Rigid foam boards can also easily be applied, but they aren't able to be used in all the applications of the other types. Cellulose requires a blower, and spray foam requires a special sprayer and a lot of protective gear.