Blown Cellulose Insulation Vs. Foam for an Apartment

Noise Reduction

• Noisy neighbors can be a major problem in apartments. Insulation is an effective way to deaden sounds that travel between floors or through walls. The sound transmission class, or STC, rating of a material lets you know how well it reduces the transmission of sound. According to the Uniform Building Code, apartment walls should have an STC rating of 50. This rating allows occupants to hear loud speech from a nearby unit, but not understand what’s being said. Blown-in cellulose can be installed in a way that achieves a 50 STC rating. Polyurethane foam can be semi-rigid or rigid. The semi-rigid foam has an STC rating of 51, but the rigid foam only has a rating of 43.

Advantages

• Blown-in cellulose is made from recycled newspaper and cardboard, which holds an appeal for many people. It costs less than foam insulation and can reduce the flow of air by as much as 70 percent. Because it’s treated with chemicals, it’s resistant to fire, mold and insects. Spray-on foam can form a better seal than blown-in cellulose by completely filling in cracks and empty spaces. This means there’s no airflow at all, and the insulation also functions as a vapor barrier. Spray-on foam also has a higher R-value than cellulose and, because it’s rigid, it adds to the structural support of a building. It won’t deteriorate and it can’t mold.

Problems

• Loose-fill cellulose settles as much as 20 percent during the first few years after its installation. This reduces its R-value and its ability to cut down on noise. Polyurethane foam also loses some of its R-value when gases escape from the foam and are replaced by air. Polyurethane foam requires more skill to install than blown-in cellulose. Some polyurethane foam can expand so rapidly that it damages the walls.

R-Value

• Insulation is given an R-value that indicates how effective it is at resisting the flow of heat. The higher the number, the more effective the insulation is. Polyurethane spray foam is an excellent insulator with an R-value between 3.5 and 6.5, depending on the product. Blown-in cellulose has an R-value between 3.6 and 3.8 per inch.

Cost

• Blown-in cellulose insulation is less expensive than spray foam, costing under $1 per square foot at the time of publication. Polyurethane spray foam runs between $1.25 and $3.50 per square foot. The higher cost is due to the fact that it takes more skill to install. Since spray foam forms an air barrier, you may be able to save on other costs like caulking or applying a vapor barrier.