Do Rock Wool, Slag Wool, or Mineral Wool Insulation contain asbestos fibers?
Because these mineral fiber insulation products are often applied by spraying as a wet slurry onto building surfaces or into building cavities, they should not be covered by a vapor retarder barrier until the insulation has dried. We recommend using a long-probe moisture meter such as models made by Delmhorst™ to assure that the rock wool sprayed into building cavities has dried to ambient indoor humidity before the wall or ceiling is covered with a vapor retarder or enclosed. Mineral wool insulation is used by some manufactured home and possibly some mobile home manufacturers. Because these structures are later transported to their ultimate building site the insulation is exposed to vibration that can cause settling of the insulation within building cavities. Wet-process blown-in mineral wool insulation thickness can decrease by up to 16% in this case, according to Graves and Yarborough. What the study did not examine, and which may be still more important, would be the development of
