Removing the problem depends on the type of fungus responsible and the degree of infestation.
Floor joist mold growth.
Thirty percent moisture content is saturated wood so when the joists get this wet you have a serious problem and need to be installing a crawl space encapsulation system.
Although mold is most common in wet and humid climates it is still relatively common in many other places.
Mold spores in the air.
Thankfully even this level of mold growth can be addressed without replacing the joists though the amount of work required is still substantial.
A variety of fungi can result in mold or mildew on floor joists.
Heavy mold growth on tji joists from new construction.
So don t ever agree to pay for spraying for mold on floor joists unless the pest control contractor insists the moisture content of the floor joists are 25 or higher.
While this is clearly an extreme case mold growth on the joists is fairly common if a home is built during the winter months.
However something that commonly gets overlooked is your floor joists and subfloor also known as your basement ceiling.
If left alone mold in joists can eventually become such a problem that it can only be removed by professionals.
As mentioned before all mold needs to grow is a food and moisture source.
Beyond that some factors that contribute to a higher chance of mold growth include.