To supersede the requirement for top plates stated in Sentence (1) and permit lintels with splices to serve the function of the top plates.
These minimum dimensions for metal splices, and wood splices and their fasteners are to limit the probability of discontinuous support at the ends of lintels, which could lead to lintels being unable to resist expected lateral loads, which could lead to the excessive deflection or failure of walls.
Where assemblies are required to provide fire resistance, this is to limit the probability of compromised fire resistance of the assembly, which could lead to harm to persons.