Fiberglass insulation emerged as a competitor to cellulose insulation some time ago, but has been refined over the years to the point where it is the preferred choice for many blown-in attic insulation installers.
Fiberglass insulation is made from small chunks of recycled glass mixed with sand, which gives it superior properties in both sound deafening and water resistance. Over time, the product has been improved significantly to increase energy performance and eco-friendliness. Fiberglass insulation is fire, water and mould resistant, has stronger R-values over cellulose insulation, never settles, can expand up to 17x its size, and offers a virtually dust-free installation. In addition, fiberglass insulation can be blown-in right over top of an existing product without issue. The only drawback with fiberglass insulation is that it is slightly more expensive than cellulose insulation.