In our work with older homes, we are always surprised to see how many homes have not had additional insulation added to supplement what little may have initially been installed. This is especially evident in our valley's historic homes in that many of them were never insulated in the first place.
Homeowners have a wide selection of choices for upgrading their home's insulation. The types we recommend most often are blown cellulose and spray foam insulation. They are excellent alternatives to the much used fiberglass, and are much friendlier to the environment.
Foam insulation is the best at both insulating and air sealing. It's downside is it's initial cost to install is many times higher than blown cellulose.
Cellulose is an excellent choice because it is made from 80% post-consumer recycled newsprint.
The newsprint fiber is chemically treated with non-toxic borate compounds to resist fire, insects, and mold. The Cellulose Insulation Manufacturers Association claims that insulating a 1500 sq. ft. house with cellulose will recycle as much newspaper as an individual will consume in 40 years. Cellulose also requires less energy to manufacture than fiberglass. The Environmental Building News reports that fiberglass requires approximately eight times more energy to make when adjusted to reflect energy cost per installed R-value.
Blown cellulose can be installed in new or existing structures in attics and walls. Construction-savvy homeowners might be able to install it themselves in open attic spaces. You can use blowing machines from rental centers or building material centers to blow numerous bales of product into the attic. The process requires two people to use the equipment. A great deal of care must be taken to apply the insulation properly and protect yourself and your ceiling from damage in the process.
Our recommendation is to have the process done by professionals. This is especially true regarding insulating walls either during remodeling or retrofitting existing walls.