Spray Foam vs Cellulose Insulation: What’s Better for Your Home?

Are you looking to insulate your home but unsure of which insulation material you should choose?

Your home’s insulation helps lower your heating and cooling costs by keeping your heat from escaping outside during the winter and slowing down heat from entering during the summer.

Minnick’s helps homeowners maintain comfortable indoor temperatures with a combination of air sealing and insulation work. In this article, we compare the difference between Spray Foam Insulation and Cellulose Insulation in thermal resistance, sound insulation, safety, and cost to help you make an informed decision on what’s best for your home.

R-Value (Thermal Resistance)

Insulation materials slow down the flow of heat. During winter, heat flows through your ceilings, floors, walls, and eventually ends up outside. During summer, heat moves in the opposite direction, from outside to inside your home. The heat will always flow from warmer to cooler areas until the temperature evens out.

An insulation’s ability to slow down this heat flow is defined as its R-value or thermal resistance. R-value is a measurement of how resistant insulation material is to temperature differences. Insulation with a higher R-value will perform better than insulation with a lower rating.

Spray Foam Insulation

Spray foam insulation is sprayed into the walls of your home until it completely fills the entire space, no matter the shape of the area. Spray foam comes in two varieties; open-cell which has an R-value of 3.2 per inch and closed-cell which has an R-value of 6 per inch. The ability for spray foam to fill into any space or shape allows it to offer a high R-value per inch.

Cellulose Insulation

Cellulose insulation comes in two varieties: dry fiber that is blown into open attics and enclosed cavities and damp fiber that is sprayed into open wall cavities. Both varieties are composed of recycled newsprint with chemical additives. The difference is that sprayed cellulose is dampened with water and sometimes a little adhesive is blended into the mix. No matter which option you choose, cellulose insulation offers an R-value of 3.5 per inch.

Conclusion

When comparing just R-value, there is little difference between insulation materials. The R-value of cellulose insulation ranges from 3.6-3.8 per inch and spray foam insulation ranges from 3.5-3.7 per inch of insulation. Given that both insulators are equal in R-value, the difference in thermal resistance relies heavily on proper installation and air sealing. Since spray foam has the ability to form its own air seal due to the way the mixture is applied, it offers slightly better thermal resistance. Winner: Spray Foam Insulation

Sound Insulation

Insulating your home has the added benefit of making your home more soundproof. Not only does insulation help control your energy costs and indoor climate but it also improves the level of sound control between your interior rooms. Due to the density of insulation, it can help diminish noises from other rooms and even outside. An insulation’s ability to deafen noises is often measured in STC (Sound Transmission Class). STC measures the decibel (dB) decrease as sound passes through a material. 

Spray Foam Insulation

Spray foam is polyurethane foam that can block or resist sound waves or vibration. It’s great for deflecting noise, but not as efficient at absorbing it. Spray foam helps to muffle or reduce sounds from moving between floors and rooms due to the dense nature of the material. Spray foam has an STC of 39 for open cell and 37 for closed-cell. 

Cellulose Insulation

Cellulose insulation is composed of 75-85% recycled paper fiber with the remainder being made up of fire-retardant matter. It reduces vibrations within a wall or ceiling to absorb sound and reduce echo feedback. The more loosely packed the fibers, the better their ability to absorb and dampen sound. Cellulose insulation has an STC range from 44 to 68 depending on its density.

Conclusion

When comparing the ability to control sound, cellulose insulation offers superior soundproofing compared to spray foam insulation. Using cellulose insulation can absorb sound from outside your home and between rooms when added to your interior walls. Winner: Cellulose Insulation

Spray Foam v Cellulose CTA

Safety

When deciding on the material to fill your home’s walls with, safety is an important overlooked factor. Some insulation materials are treated with hazardous chemicals while others are eco-friendly. In fact, there are no insulation materials that are 100% safe, so understanding the difference in this category is important for the safety of you and your family.

Spray Foam Insulation

Spray-foam insulation has become a popular choice for many homeowners because it fills spaces completely, creating an effective air seal in addition to insulating.

Spray foam is often promoted as a green building material for its ability to improve energy efficiency. However, spray foam insulation is composed of a hazardous chemical called isocyanates.

This chemical has been linked to causing asthma and other respiratory issues. This is a notable concern if you or your family have asthma. The toxic chemicals in spray foam insulation also pose another great safety concern. In the event of a fire, spray foam is easily flammable and will release toxic fumes once it ignites. For this reason, foam insulation installed in attics and walls must be covered by a fire ignition or fire-resistant thermal barrier.

Cellulose Insulation

Since cellulose insulation is mostly made from recycled newspapers, it is considered to be among the safest materials for home insulation and considered a green product. Due to cellulose’s organic material, it can be eaten by insects, fungi, and used as nesting material for rodents. To repel pests and reduce flammability, cellulose manufacturers chemically treat the material with a fire retardant such as borate. This results in approximately 20% of the cellulose consisting of chemicals. These added chemicals add fire-resistance but does not completely eliminate the fire hazard. If cellulose insulation absorbs water, the chemical fire treatment will be destroyed.

Conclusion

When weighing safety, cellulose insulation is a much safer option for you and your home compared to spray foam. Cellulose is made of 80% recycled paper, while spray foam is made from petroleum distillates. Cellulose has more recycled material than any other insulation material and it doesn’t require the emission of any greenhouses to install like spray foam. Furthermore, cellulose is approved as both a fire block and an ignition barrier. Winner: Cellulose Insulation

Cost

Like with any home improvement project, the cost is always an important factor in the decision-making process. The cost of insulation materials is measured by the amount of square footage used.

Spray Foam Insulation

Spray foam insulation is a premium material compared to cellulose. In most cases, the cost of spray foam can range from two to three times higher than the cost of cellulose. One big reason for this stark price difference is that most spray foams have to be purchased directly from the manufacturer, unlike cellulose which you could find at your local Home Depot. Another price factor to consider is that spray foam requires a professional and special machinery to install. If considering spray foam, be sure to factor in labor cost into the final cost of your project. On average, the cost to insulate an attic in a 1,500-square-foot house with spray foam can range between $5,000 – $10,000.

Cellulose Insulation

Cellulose is a very inexpensive insulation material in comparison to spray foam. The fact this insulator is made up of recycled materials is a big reason behind its economical price-point. The install of cellulose does require the use of a large motorized blower, which is usually best left to a professional. Depending on if you are the DIY type, you’ll need to either factor in labor cost or rental cost for a blower. Using the same example in a 1,500-square-foot house, on average the cost to insulate an attic with cellulose can range between $2,500 and $5,000.

Conclusion

One final thing to keep in mind when it comes to the cost of insulation material is the money you will save from the added energy efficiency. Even though spray foam has a higher upfront cost, the lifetime costs are actually much lower in comparison. Cellulose will eventually sag, shift, and settle over time, which means you’ll need to regularly maintain it and eventually replace it. You won’t have that worry with spray foam insulation, as it stays right where it is applied for the life of the house unless someone removes it. Spray foam insulation also has the ability to form an air seal that will keep the outside temperatures and lower your utility cost as a result.

Depending on your specific goals, you may prefer the smaller upfront cost of cellulose insulation, but we’d encourage you to weigh the long-term cost-savings of spray foam insulation. Overall, we’ll call spray foam the winner in terms of cost due to it having lower maintenance cost and it’s cost savings from improved energy efficiency. Winner: Spray Foam Insulation

Spray Foam v Cellulose Chart

Is Spray Foam or Cellulose Insulation Best For You?

The four most important factors when choosing an insulation material for your home are R-value, soundproofing, safety, and cost. Regardless of which material you choose to insulate your home with, any form of insulation is better than no insulation.

Spray foam is the better choice when it comes to long-term cost and thermal resistance.

If you prefer using safer and eco-friendly materials that offer good sound control at an affordable price point, then you may prefer cellulose insulation.  Minnick’s is Maryland’s leading home performance contractor with over 65 years of experience. We conduct whole-home energy audits to identify air leaks, cracks, and other sources of energy loss. If you’re interested in learning more about your options for insulating your home, check out the Minnick’s Learning Center for additional articles on improving your home’s comfort.