What non-compliant mitigation decision would most likely cause re-entering of radon into a home?

Venting a sub-membrane depressurization system at the rim joist is a non-compliant mitigation decision that can lead to the re-entry of radon into a home. This is primarily because when exhaust air is vented at the rim joist, it can create negative pressure around the sub-membrane area. If this negative pressure is not properly managed, it could draw air from the outside or from the spaces above the membrane back into the home, which can inadvertently pull radon-laden air along with it.

In proper radon mitigation practices, exhaust points are ideally placed so that they do not create pathways for radon to re-enter the living space. Proper placement of the venting system is critical to ensure that radon gas is effectively removed and that it does not find an inadvertent route back into the home through pressure differentials.

The other options, while all relevant considerations in mitigation practices, do not inherently pose the same risk of radon re-entry. For example, installing windows in the basement can provide ventilation, which may help reduce radon levels, whereas sealing cracks in the foundation aims to prevent radon infiltration. Using a radon barrier membrane can also effectively block radon from entering the building. These actions