What is the minimum bearing for wood floor joists on masonry?

• A. 2-1/2 inches
• B. 2 inches
• C. 1-1/2 inches
• D. 3 inches

Answer: (D)

Minimum bearing is the portion of the joist end that must rest on the supporting surface to transfer its load safely. For wood floor joists on masonry, this bearing should be at least three inches. That extra depth distributes the load over a larger area of the masonry, reducing the risk of crushing the mortar joints and ensuring the joist sits firmly even if the wall or surface isn’t perfectly flat. If you tried to use a smaller bearing, like two inches or less, you’d increase the chance of mortar damage, uneven seating, and potential floor movement. The three-inch requirement provides a reliable, stable seat for the joist on masonry.