Cellulose Insulation Pros and Cons

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R-values of loose-fill insulationThere are three main types of conventional loose-fill insulation used in the walls and ceiling of residential and commercial buildings: fiberglass, cellulose and mineral wool . Each has certain advantages and disadvantages. This article looks at the second of the three – cellulose insulation.

What is it?

Cellulose is a loose-fill insulation that comes in two types: dry and wet. It is made of recycled paper , consisting primarily of newspaper but also including some cardboard and other appropriate papers. It is the best environmentally-conscious option because it is sourced in the recycling arena, though it is treated before use as insulation. The "wet" option is exactly as it sounds – slightly damp when it is sprayed into the cavity.


  • Cellulose insulation helps reduce the mountains of discarded paper and cardboard created by a paper-hungry society.
  • Cellulose is treated with boric acid, which increases fire resistance, resists mold and makes it unpalatable to insects.
  • Some cellulose insulations are treated with an acrylic binder which ensures it settles when installed, thus reducing the long-term decrease in R-value.
  • Cellulose is generally cheaper than fiberglass insulation (up to 25% cheaper, in some cases).
  • The R-value of cellulose (roughly R-3.2 per inch) is higher than that of standard fiberglass (R-2.2 per inch).
  • The health risks from cellulose are far fewer than those from fiberglass.



  • Installation costs for cellulose can be higher than for fiberglass.
  • Cellulose insulation creates an enormous amount of dust when it is installed, so a certified breathing mask is absolutely essential.
  • Dry-blown cellulose sags and settles, reducing its R-value over time.
  • Cellulose insulation absorbs moisture easily, which not only reduces long-term efficiency but can cause the insulation to mold and rot. Even wet-blown cellulose can suffer from these effects.
  • Both dry- and wet-blown cellulose need a vapor barrier.