Wood girders in contact with the ground must be what type of wood?

Wood girders in contact with the ground must be pressure-treated wood to ensure durability and resistance to decay, insects, and moisture. This treatment process infuses the wood with preservatives that protect it from rot and pests, which is particularly important in outdoor settings or in areas where the wood may be exposed to water or soil conditions.

Choosing pressure-treated wood helps to extend the lifespan of the girders, making it a vital requirement in construction practices. Other types of wood, such as composite wood or plywood, may not have the necessary durability for direct ground contact, while untreated wood is highly susceptible to moisture absorption, leading to deterioration and structural failures over time.