The ends of untreated wood entering exterior masonry or concrete walls must have how much air space around them?

For untreated wood that enters exterior masonry or concrete walls, maintaining an air space of 1/2 inch around the ends is crucial for preventing moisture-related issues. This air space allows for proper ventilation and helps to reduce the likelihood of wood rot and damage due to moisture that could be present in the masonry or concrete. By ensuring that there is adequate space, it allows the wood to dry properly if any moisture does come into contact, thereby extending the life of the wood and maintaining the structural integrity of both the wood and the surrounding masonry or concrete surfaces. This requirement aligns with building codes and best practices in construction to ensure durability and safety in building structures.