Mold and mildew are types of funguses that tend to grow in areas with excess water and humidity. These funguses spread through your home and move into areas with excess moisture and little ventilation such as the floor joists in your crawlspaces. They land there and begin to grow. Remove mould and mildew growth as soon as you notice it.
Bleach is a common cleaning solution that will kill and remove mould and mildew. To use it, mix 1 cup bleach with 1 gallon water. Spread the cleaning solution over the mouldy joists. Let it sit for at least 20 minutes to give the bleach solution time to loosen the mould and mildew growth.
White vinegar is an alternative to the bleach cleaning solution. White vinegar is a natural disinfectant that will kill mould and mildew spores. It is completely non-toxic and natural. To use it, fill a spray bottle with white vinegar and spray it over the surface of the mould growth. Let it soak for at least 20 minutes.
Once the mould or mildew is loosened from the surface of the joists you will need to scrub it to remove it completely. Scrub from top to bottom until all of the mould and mildew is free. Wipe the mould residue off with a clean paper towel. Throw the paper towels away as soon as they are covered in mould and mildew.
Cloths will help you dry the joists after you've cleaned and rinsed them with clear water. Drying the joists is incredibly important to help prevent the mould spores from landing back on the joists and beginning to grow there again. Rub the cloths over each joist until it is completely dry.