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Cellulose as thermal barrier

dwilliams123 | Posted in General Questions on

Trying to clarify when cellulose is considered a thermal barrier. Is there a Code for this, or is it based just on what the maker of the cellulose says?

And only wet/damp cellulose can be a thermal barrier, correct? Blown cellulose can never be considered a barrier?


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  1. Expert Member
    Dana Dorsett | | #1

    As a timed thermal barrier against ignition it has to be tested by the manufacturer, and will have a certifcation lab's report to back it up. There is no generic answer to this that applies to all cellulose products, damp sprayed or dry.

    Similarly there is no generic answer about qualifying as a fire-stop inside a framed wall cavity, but most qualify at 18" of depth/height in the cavity at typical (non-dense packed) densities, possibly less if dense packed.

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