Should I add fiberglass or cellulose to my attic insulation?


Should I add fiberglass or cellulose to my attic insulation?

Asked by Marsha

This is in addition to whatever is up there now.

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Edward Wright's picture


Yes! Unlike mechanical systems, insulation, provided it's kept dry by maintaining your roof and its flashing, will not wear out. It's a great long term investment.

Take several measurements to get an average depth of your current attic insulation and compare that to the EPA insulation level recommendations here. For example, adding R38 to an existing 3-4 inches is the baseline recommendation for your climate zone.

Also, do not forget to check insulation under your floors that are over unheated or poorly heated areas. The EPA recommends they should be at least R25.

  • The key to installing batt insulation is a tight full thickness fit, not 'crammed' in and compressed.
  • Check out the EPA's DIY Guide (here) for more information.

These areas are two of the easier retrofits and can be good Do-It-Yourself projects to see an even greater return on your investment in the materials.

Best of luck with your project, Edward

For more information:

Read "Is three inches of batt insulation enough for my attic?" a Q&A answered by Steve Saunders.