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Is blown mineral wool in crawl space harmul?

Lawrence Steffen | Posted in General Questions on

Had wool-like insulation blown in roof crawl space 30+ years ago. Wool insulation has found it’s way into ventilation system causing excessive dust in house. Is the insulation harmful? What will mitigate the dust. Had ductwork cleaning a few years ago but return system has been infiltrated with insulation. Should visible insulation be removed to help with oily dust.

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  1. GBA Editor
    Martin Holladay | | #1

    I'm not sure what you mean by a "roof crawl space." Probably you mean something like "a cramped attic."

    Duct systems are required by building codes to be "substantially airtight." When a duct system is installed properly, the duct seams are sealed with duct mastic or a high-quality tape, to ensure that the duct system is as airtight as possible. Unfortunately, many duct installers ignore this code provision.

    If your duct system is leaky enough to pull insulation fibers from your attic and distribute those fibers throughout your house, you have a problem. The best solutions are either:
    (a) to seal all of the leaks in your duct system, or
    (b) to replace your leaky duct system with new sealed ductwork.

    Ducts are often difficult to access, making this type of work expensive. That said, it's certainly possible to remove your old duct system and to replace it with a new system.

    If the cost of fixing your duct system is daunting, and if your existing heating and cooling system is on its last legs, you might consider abandoning your ductwork and instead installing ductless minisplits to providing heating and cooling.

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