Splices are required when a beam is either too long or too heavy to install safely. When a beam spans two party walls, a splice is also recommended to easily install the beam. As a rule of thumb, the flange plates need to be at least the same thickness as the beam’s flange, and the same rule applies to the web plates.
Beams can be spliced together with a web and flange plates or, if space is limited, using a welded end plate.