Containment is one of the simplest engineering controls used in mold remediation and is also one of the most important. This is your first defense against cross-contamination – it helps to control the flow of air, therefore minimizing cross-contamination and protecting occupants.
Containment can range from something as simple as covering an affected area of drywall with plastic, to as extreme as containing the entire building using air lock chambers. We classify containment types into 3 different categories: source containment, localized containment, and full containment.
Source containment is used when there is minimal mold growth on the surface of a wall or other building material. It involves sealing the visible mold growth to the building material, creating a barrier which prevents spores from releasing into the air during demolition, thus decreasing the chance of cross-contamination.
Common methods of source containment include plastic sheeting, tape, and adhesive, or other specialized products which adhere directly to the surface. The problem with using this method is that the building material being removed likely has contamination on the back side that is not visible while in place and cannot be contained until the material is removed.
Think about seeing some drywall with a minor amount of mold contamination on the surface. Many times, the area you see is much less than what is on the back side of the drywall inside the wall cavity. The framing and insulation behind the drywall may also be affected and can release mold spores when the building material is removed.
If a company is recommending source containment as the sole type of containment for surface growth, they should verify that there is no contamination hidden behind the visibly affected building material. This can be confirmed with a specialized camera used to look inside the wall cavity, or by testing the space and surfaces inside the wall.