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Question DetailsAsked on 2/19/2018

my house was built in 1956 by gunnison us steel is my insulation in the attic vermiculite tainted with asbestos

if it is, should in go to the expense of removal or should I cover it with blown in insulation over it?

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1 Answer


Considering that in that timeframe the expanded vermiculite insulation being produced in the US had asbestos in about 80% or more of it, probably so. Plus, if you have the Gunnison metal-panel walls, they were made with asbestos cement infilling.

Now - as to whether to remove or not - first, unless it has over 1% asbestos in it, the EPA does not regulate it nor consider it a hazardous waste when handled and disposed. Second, unless it is disturbed, there is no risk - the risk is from airborne fibers being breathed in and to a much more limited extent, getting in the eyes.

Testing runs about $75 for a DIY mail-in kit, more like $250-300 for a test by a certified (hence certified test results for that house) by an asbestos testing and abatement company.

Note that it is only considered "hazardous" if disturbed, putting dust/fibers into the air - there is nothing in general (though some lenders have restrictions) on leaving it in place undisturbed.

There is the issue of resale problems - some buyers will not want a house with possible asbestos in the insulation even if it has been stabilized and covered - talk to your favorite attorney about that. In CA, OR, WA, and CO for instance that can be a big issue to many buyers, in many other states a non-issue for most. Also, some lenders worry about it and will not give a home purchase loan on a house with it, other don't care - but it is at least a consideration.

Do NOT just blow-in over it - that does not meet containment standards, plus the blowing-in will dust up the vermiculite and mobilize some asbestos fibers. it has to be encapsulated with a special (usually resin) spray to "fix" the surface in place - not a major cost to do that. Then blown-in insulation can be put over it. One problem with the fixative spray though - because it is like a paint, it acts as a partial vapor barrier, so there has been some articles in the building trades press about condensation problem in the insulation under the spray layer if the house has excess air flowing through penetrations into the attic.

Also - if blowing in over vermiculite, I emphatically recommend against cellulose - it mats down a lot and absorbs moisture, but also acts as a partial vapor barrier over the far more permeable vermiculite, which can be a bad thing unless the attic penetrations from the house have been sealed up, because you can get a moist/frosted up layer in the top of the insulation which can mildew/mold, and also as it fills up with moisture blocks the evaporation of the moisture so can make the problem worse. In extreme cases, I have seen ceiling fall in from the weight of the moisture/frost in the insulation, and badly rotted attic framing.

So - sort of a catch-22 situation - certainly removing it and getting a certificate of abatement from a licensed asbestos removal contractor makes the problem totally go away, but at probably $5-15 per attic floor SF additional cost - so commonly $10,000 plus or minus ballpark range. Removing it also is the prime time to seal up penetrations into the attic through ceiling or walls too, making for a better attic situation all around.

BTW - if adding or reinsulating, be sure to read up on the need to provide good ventilation through the attic (normally on sloping roofs from eaves to ridge vent works best), the need for baffles at the eaves to prevent insulation from blocking them, and the need to use compressed air to blow clean the eave screening after the insulation is blown in.

Here are some articles on the source of the problem, the risks involved with leaving it or removing it, and especially information on the zonalite trust fund which will reimburse a portion of properly documented abatement costs, FYI:

Answered 2 years ago by LCD

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