Crawl spaces are notorious for having problems with moisture and condensation. Over half of all houses built with crawl spaces will have issues with excessive condensation. It is important that a crawl space with extra water vapor id dealt with promptly. If it is left to have too much moisture for a long time the crawl space will develop worse troubles. Mold will grow and continue to spread. The wood sub floor and joists will begin to rot. The foundation of the house could be weakened letting in more water. The more water issues are left to worsen the more work intensive and expensive the repairs will be to fix the crawl space.
It is important to identify the source of the moisture in your crawl space. If it condenses because there is not enough air circulation in the crawl space, start by checking to see if the crawl space vents are blocked. If so remove the debris and if the vent covers are damaged replace them. Consider having a vent with a fan attached installed.
If getting the air circulating in the crawl space doesn’t take care of the vapor problem, try to figure out where the moisture is getting into the crawl space and address the problem. If it is coming up into the space from the dirt floor and there seems to be a lot of moisture you should install a sump pump. You might want to invest in a dehumidifier as well. This will keep the moisture from condensing and sticking to the wood and other surfaces causing mold. It would also be a good idea to cover the dirt floor with plastic to keep water out of the crawl space.
There are some things you can do to fix water seepage which is coming in through the cement foundation walls of the crawl space too. You should start by checking the gutters around the outside of the house. Clean them out and repair any leaks. See that the downspouts drain several feet from the base of the house. Make sure that the ground around the bottom of the home is at a grade which moves down and away from the foundation.
If the crawl space is still having water vapor issues paint the walls of the foundation with Dry-lock. This is a substance that is like paint, cement, and rubber all mixed together. It is pricey but does a good job of sealing the walls. If that isn’t something you want to deal with, you could install a vapor barrier around the foundation walls and across the dirt floor of the space. The vapor barrier can also be installed underneath the sub floor so the whole crawl space has been covered by the vapor barrier. This should take care of the moisture.
Call a professional to assist you if there is still a problem with water as the process to get rid of the problem will be more complex if all the above fixes did not work. It is likely that the ground outside of the foundation will have to be dug up and drains will have to be put in around the foundation. French drains may have to be installed in the yard to drain water away from the house as well.