Untreated wood floor joists must be a minimum of how far from the ground?

The correct choice is based on building codes and practices designed to ensure the longevity and safety of wooden structural elements. In North Carolina, untreated wood floor joists must be a minimum of 18 inches above the ground. This distance is crucial because it helps prevent moisture-related issues that can result from direct contact with the ground.

When wood is in close proximity to the soil, it is more susceptible to decay, mold growth, and insect infestation, particularly from termites, which thrive in damp environments. Elevating the joists above this threshold allows for better air circulation, reducing humidity levels around the wood and extending its lifespan.

The requirement for a minimum of 18 inches is rooted in established safety standards aimed at protective measures for wooden structures, helping to ensure durability and safety for residential buildings.