Attic insulation is one of the most important factor that come in play when looking at your homes overall performance.
Attic insulation is measured in R-value (R= resistance to heat flow) which is rated per inch. There are many different types of attic insulation but here in the phoenix valley area there are 2 types that are the most common.
The 2 types are cellulose and fiberglass, both of which are blown in. Cellulose was the go to for many years, this insulation is the shredded newspaper looking insulation you’ve probably seen before. Cellulose has an R-value of R-3.7 per inch.
The new most common insulation for new builds as well as retro fit jobs (retro fit is a job done to an existing home) is blown in fiberglass. This insulation is usually pink and fluffy. Fiberglass insulation has an R-value of 2.8 per inch. Although by just that information, it doesn’t really make sense for the industry to have sitched to fiberglass for cellulose, there is one major issue with cellulose that made the switch a no brainer.
Cellulose insulation is very dense and this causes the insulation to compact itself over the years, which drastically reduces its performance, in turn leaving the home with uneven temperatures and an electricity bill constantly going up. Fiberglass however is guaranteed not to loose more than 2-4% of its R-value for 100 years (manufactures use the term “life of the building” for legal reasons).