Hard rot is a type of wood decay caused by specific fungi that break down the cellulose and hemicellulose in the wood. This process leads to a loss of structural integrity, making the wood feel hard and brittle. Unlike soft rot, hard rot results in a more severe deterioration, often leaving the wood with a dark, dry appearance. Commonly found in timber exposed to moisture, hard rot can affect various types of wood, including oak and pine. Preventative measures include proper sealing and maintenance to reduce moisture exposure, which helps protect against fungal growth and prolongs the lifespan of wooden structures.