Ends of ceiling joists shall be lapped a minimum of how many inches?

The requirement for ceiling joists to have a lap of a minimum of 3 inches is based on structural integrity and load distribution. This lap helps to ensure that the connection between joists is strong enough to support the weight of the ceiling materials and any additional loads that may be applied over time, such as insulation or fixtures. A 3-inch lap creates a robust interconnection that enhances stability, reduces the likelihood of sagging or failure at the joints, and helps to maintain the overall alignment of the ceiling structure. Ensuring adequate overlap is essential for meeting building codes and standards that provide safety and durability in construction.