Prior to 1980, many building materials manufactured in the U.S. contained asbestos. This was due in large part to its fiber strength, heat resistant qualities, low cost to mine, and abundant availability. 

It is standard practice for restoration contractors who work in older homes to have materials suspected of containing asbestos tested, especially interior finishes such as plaster and drywall taping compound. Even though USEPA banned asbestos in all building materials in 2019, inspection and testing must be performed regardless of the date of construction where a renovation will occur.

If the test samples indicate that asbestos is present, then a certified asbestos abatement contractor will need to perform abatement work before any restoration services begin.

Post-Asbestos Abatement Testing

Once the asbestos is removed, a third-party testing company should perform post-abatement air sampling to be sure the asbestos abatement work was done properly. This is commonly known as a clearance test. If the clearance test fails, the abatement contractor must decontaminate the areas again and call for another clearance test. Once the clearance test passes, the abatement contractor will dismantle their containment units and remove their equipment so repairs can begin.

However, safety precautions need to be taken when repairing drywall or plaster that contain asbestos. The process of patching drywall or plaster requires that the joints, corners, edges, and seams be sanded to blend the texture so you can’t see where a patch or repairs took place. This can cause widespread contamination as the process to repair these materials requires disturbing surrounding areas where old ACM may be disturbed.

Restoration contractors that inadvertently create asbestos contamination during interior drywall or plaster repairs is becoming all too common.

ACM Precautions

As a rule of thumb, if you perform repairs in a building where sections of ACM have been removed, be sure to take proper precautions to prevent secondary asbestos contamination.

Here are three options to consider when hiring a contractor to repair drywall or plaster that is asbestos-containing material (ACM):

Apply a layer of a skim coat of new taping compound for the entire wall or ceiling surface so it can be sanded without disturbing the ACM. 

Apply a layer of ¼” sheetrock over the entire surface area that needs repair. This will prevent sanding into the ACM. The challenge here is you may also have to replace baseboards, casing, crown moldings, and move outlets and switches forward. 

Have the entire wall or ceiling that has ACM abated and then replace the removed sections with new material. 

Keep in mind wet sanding is still sanding and when the wet ACM dust dries, it can become airborne. Even “dustless sanding” creates some dust and will also contaminate the sanding equipment. 

As a rule of thumb, if you repair drywall or plaster that contains asbestos, consider suitable options to eliminate any risk of disturbing ACM and causing contamination. To avoid potential liability, obtaining clearance air samples after repairs are done can provide you and the building occupants with proof that you did your work properly.

Illinois Environmental Contractors Association Resources

For more information on finding a local contractor to assist with professional asbestos abatement, check the resources below:

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