BobVila.com

Mastic

Hi...read your post.

I work in the construction industry in NYC, specifically in school construction.
The city runs into asbestos containing materials "(ACM)" everyday. Your situation is not unlike most where there was either an ACM floortile or ACM mastic @ the molding. In those cases putting down another layer of floor tile is perfectly acceptablable & in accordance w/ city specifications pertaining to that work.Bear in mind that these are schools and the risk is not takien lightly. Thus, if it good for the most it should be safe for you as well.

ACM comes in many shapes and sizes. & as the gent said before me, when it's airbourne that is when there is the greatest risk. On the risk spectrum gummy sticky substances (mastic & caulking) are on the low end in that they hold on the asbestos and are less inclined to release fibers. A higher risk situation is where the ACM is what is known as "friable" in that it crumbles, creates dust and releases fibers into the air. This is usually the case with plasters, cements, wire & duct insulations.

If you go the removal or "abatement" route. You should obtain quotes from 3 plus contractors. In that quote should include "air monitoring" results for the house, "airlock containment" for the area of work.

The air monitoring is exactly that. Your contractor sets up a apparatus that sucks in and samples the air. The air passes thru a cassette and is sent to a lab for review. When the results come back "all clear" or negative result. it means the air is free of fibers. If the air doesnt come back all clear or comes back positive. The house is dusted and cleaned and the air sampled again until an all clear is achieved.

Note; in your case since the condition is mastic and not friable there is a very low chance getting a positive air result. In the case where a positive result has come back it is usually due to a dusty, construction condition triggering a lab finding and not asbestos fibers.

Hope this helps. your gut has been accrurate thus far. Dont do what most people do when they hear asbestos...that is freak out. There are protocols and methods for restoring areas to safe occupation after ACM has been discovered.

Best,

Froggie 99