The mold is strong enough to infiltrate a wood or concrete foundation from below, and quickly take over an entire house. It stays hidden, and spreads fast. Unlike most molds which grow on the surface of material, poria can deeply penetrate objects, causing a loss of structural integrity. Because it grows on the inside of objects, these objects cannot be saved (and this often includes the frame and foundation of a house). Houses have literally collapsed due to a poria incrassata infestation.