GBA Logo horizontal Facebook LinkedIn Email Pinterest Twitter Instagram YouTube Icon Navigation Search Icon Main Search Icon Video Play Icon Plus Icon Minus Icon Picture icon Hamburger Icon Close Icon Sorted

Community and Q&A

Is 35 year-old under-attic-floor fiberglass insulation a health issue?

greenhouse437 | Posted in Energy Efficiency and Durability on

I’m asking about the formaldehyde issue. We’ll be spray foaming the attic soon–R38 rafters and R21 gable walls. The contractor would like to remove as much of the under-floor fiberglass as possible to make it a better conditioned space. We’re not so inclined, since our attic will really only be for storage, central AC maintenance, etc. and as long as the temps up there don’t vary by more than a few degrees, the winter cold or summer heat outside shouldn’t affect us in the floors below. We also have full doorway/stairs to the attic, so we can equalize the temps anytime we want to go up there just by opening the door.

If, however, this yellow paper-backed fiberglass is likely to present a health hazard, then we might consider removing it. And if we do, we’re not sure it should be by a company that it mainly geared to spray foaming. Perhaps there are certain procedures or equipment required to ensure that removal itself doesn’t stir up the toxic materials. Our contractor has a high suction volume cleaner that sucks out the fiberglass after they break it up by hand.

Ah, every project in an old house that starts out looking simple always takes more research and time to do it right….

GBA Prime

Join the leading community of building science experts

Become a GBA Prime member and get instant access to the latest developments in green building, research, and reports from the field.


  1. GBA Editor
    Martin Holladay | | #1

    There is no reason to believe that 35-year-old fiberglass insulation is a health hazard. Most homes in the U.S. have fiberglass insulation that is about that old.

  2. greenhouse437 | | #2

    Thanks for your reply; I just found out from the prior owner the fiberglass was already there when they arrived, so it could be as new as the mid-1970s or earlier. Not sure when fiberglass use became prevalent in this country, but house is from 1924, and I'm thinking this would have been done in the 1960s. At any rate, probably doesn't change your answer. By now this stuff has likely off-gassed itself out...

  3. Anon3 | | #3

    How is the air quality in the attic? If you do not vent the attic, that air is going to go into your house. To find out, spend an hour in the attic.

  4. user-2310254 | | #4

    Are you planning to spray closed cell foam on the ceiling? Open cell may cause moisture issues in the sheathing.

Log in or create an account to post an answer.


Recent Questions and Replies

  • |
  • |
  • |
  • |