What does a moisture barrier do?
This is an excellent question deserving consideration as this is the most common question I get as a home inspector.
A moisture barrier reduces the relative humidity in the crawlspace, which ultimate reduces the potential for growths like mold and rot.
Water vapor from the ground disperses into the air filling the crawlspace. Once the humidity reaches 60% for a sustained period of
time, mold can grow by pulling water out of the air. Many rots can sustain growth with even less humidity. The average humidity
levels for the Nashville area is 60-80%. The goal is to reduce moisture 30 to 40% for the general health of the property.
When do I need a moisture barrier?
Our opinion is generally every crawlspace should have a moisture barrier. There is no crawlspace that could not benefit from this relatively inexpensive feature.