When moisture builds up in a crawl space, it is absorbed into the wood and foundation of the home. Fungal spores begin to grow and thrive when there is high humidity, and when spores of wood-decay fungi are activated by excessive moisture, they grow root-like structures called hyphae, which grow into the wood and break down the fibers that give wood its strength. Termite infestations are also more likely in moist, unventilated areas. Foundation moisture, wood-decay fungi, and termites and other wood destroying insects can all cause extensive damage to your home within just a few years.