What kind of wall typically requires doubled joists?

Doubled joists are typically required for load-bearing walls because these walls support the weight of the structure above them, including the roof, upper floors, and any additional loads. The additional support provided by doubled joists helps distribute the weight more evenly and provides extra strength to prevent sagging or structural failure over time. Load-bearing walls experience significant forces that necessitate this reinforced framing to ensure the integrity of the entire building structure.

In contrast, interior non-load-bearing walls do not support any structural elements above them, and therefore do not require the same level of support. Similarly, while exterior walls can be load-bearing, not all are, and they could vary in design depending on the structural requirements. Lastly, not all interior walls are load-bearing; many are simply partitions and do not need doubled joists for support, reinforcing the importance of identifying which walls are actually load-bearing when determining framing needs.