Crawl space vents that are left open actually allow more moisture to enter the crawl space because they cause condensation when the warm outside air collides with the cool inside air. You should try to dry out your insulation if at all possible. With the help of a fan or a dehumidifier, wet insulation in the attic can be dried out.

Is it necessary to insulate floor joists in a crawl space?

They most certainly should be, and they have every right to be. Floors should have insulation with an R-value of at least R-9.

Is it necessary to insulate the floor above the crawl space?

In a crawl space, fiberglass insulation placed between the floor joists will assist in keeping the floor above warm. It will also aid in the reduction of the "echo" that can be heard when walking on floors that are suspended over a crawl space or basement.

Does having water in the crawl space after a rainstorm seem normal?

In the aftermath of a heavy rain, it is not uncommon to find some water under the house. In an ideal situation, the home would have been built with a positive drain directing water toward the lowest corner of the crawl space. In the event that water does manage to find its way into the crawl space, it should drain away or evaporate within a short period of time.

Is fiberglass insulation irreparably damaged if it becomes wet?

When moisture seeps into the air pockets between the fibers, the insulation's ability to slow the transfer of heat is diminished. After all, because water is a conductor, wet fiberglass insulation is about as effective as having no insulation at all in terms of energy efficiency. Installing a dehumidifier or a fan in the area will aid in the drying of fiberglass insulation.

How long does it take for insulation to become wet?

If a significant amount of the material is capable of retaining water, it will be resistant to drying methods. In this case, you will leave the walls or wood that is in contact with the material susceptible to mold growth unpainted or stained. It is possible for a large affected area to remain wet for more than 48 hours.