Attic Insulation Cellulose Vs Fiberglass Blown In

Cellulose is more difficult to cheat than fiberglass.

Attic insulation cellulose vs fiberglass blown in.

The two main least expensive and most commonly used residential insulation materials is cellulose and fibreglass. Unlike fiberglass batts with paper backing it doesn t burn as you might expect ground up paper to. In fact many professionals consider cellulose to be more fire safe than fiberglass. Another major weakness of fiberglass insulation which does nothing to stop air from passing through it.

Cellulose has 38 better air infiltration than fiberglass. It comes in rolls and has paper backing on one side. One key insulation difference is that cellulose settles over time potentially leaving some areas in walls particularly with little or no insulation. When comparing blown in insulation both fiberglass and cellulose are nearly identical in price both costing around 0 70 to 0 80 per square foot for 6 inches of insulation.

The r value of cellulose insulation is approximately 3 8 per inch so you need about insulation that is about 10 inches thick to reach r 38. With that said most homeowners agree that blown cellulose is slightly more efficient due to the face that it blocks more air than fiberglass. Unless you opt for spray foam then the insulation choices normally come down to cellulose and fibreglass. Cellulose forms a dense continuous mat of insulation in your attic.

Once it has settled fiberglass has an r value of 2 1 2 7 per inch while cellulose has an r value of approximately 3 0 per inch. You ve probably got batts in your attic walls and crawlspace right now. Despite competing industries stating otherwise independent testing confirms that cellulose is safe and approved in all building codes. Fiberglass batts however are less expensive costing on average 0 30 to 0 40 a square foot for 6 inches of insulation.

Fiberglass manufacturers have developed blown fiberglass insulation they claim won t settle over time. The r value of fiberglass insulation is approximately 2 2 per inch so you need much thicker insulation to achieve the same r value of 38. Fiberglass is by far the most common type of insulation sold in batt form although cellulose batts do exist. Loose fill blown fiberglass insulation has another slight problem.

Installation costs for blown in insulation costs around 2 a square foot where installation costs for batts is around 1 a square foot. This keeps the air from moving within the insulation and from penetrations between the air conditioned space and the attic. Very common very problematic. As the temperature difference between the living space and attic increases the r value of blown fiberglass diminishes.