Asbestos is most commonly found behind walls or above ceilings in insulation. There are two types of insulation that may contain asbestos: insulation made with asbestos, which is most often found in houses built between 1930 and 1950, and vermiculite insulation. 70% of the vermiculite insulation in buildings today was manufactured at a site in Libby, Montana that was contaminated with asbestos, so if you have vermiculite insulation in your building, it is very likely that it contains asbestos. Asbestos can also be found in cement sheeting behind walls, patching and joint compound in walls or ceilings, textured paint on walls or ceilings, and acoustic ceiling tiles.
Don’t panic if you have asbestos insulation or any other asbestos material behind walls or ceilings in your building. As long as the asbestos material remains behind the walls or ceilings, it is not dangerous. Even nail holes and similar minor damage to walls that enclose asbestos materials are not large enough to create a health risk. If you suspect that there may be asbestos materials behind the walls or above the ceilings of your building, the best course of action is to leave them alone and take care not to damage or disturb them.
The one case in which you may need to remove intact asbestos materials behind walls or above ceilings is if you are planning a renovation or demolition which would disturb these materials. If the asbestos material is friable or is considered regulated asbestos-containing material, it must be removed before demolition. Category II non-friable asbestos materials, which have a high probability of being crumbled or pulverized, must also be removed prior to demolition. Category I non-friable asbestos materials that are in good condition, however, do not have to be removed prior to demolition unless the building will be demolished by intentional burning. If you are planning a renovation which would require you to either damage or go behind walls which you think may enclose asbestos materials, you should contact an asbestos professional, who can tell you whether or not your walls and ceilings do have asbestos behind them.
If a large portion of the asbestos material is somehow exposed, do not disturb it, but check it regularly for signs of damage or deterioration. If the asbestos material is damaged or deteriorated in any way, you should call in an asbestos professional immediately to remove or repair it. Removal may not be necessarily—if possible and practical, the asbestos professional will either seal or cover the damage to prevent the asbestos material from releasing fibers into the air. If the damage is too severe, however, the asbestos professional may have to remove the asbestos materials completely.