Under each load-bearing wall that is parallel to the joists, the joists should be what?

In residential construction, the support and integrity of load-bearing walls and the structural members above them are crucial for the overall stability of the building. When joists run parallel to a load-bearing wall, they need adequate support to bear the loads transferred through that wall effectively.

Using doubled joists under each load-bearing wall provides the necessary strength and bearing capacity. This approach helps distribute the weight more evenly, reducing the risk of sagging or structural failure over time. Doubled joists help ensure that the ceiling or floor above has sufficient support, especially in conjunction with the load-bearing wall beneath.

Other options, like using single joists or blocking, do not provide the same level of support when parallel to a load-bearing wall. While blocking can serve to stiffen floors or ceilings, it does not substitute for the structural capacity that doubled joists provide. Spacing is not relevant to this context, as it does not imply extra support needed under load-bearing walls. Therefore, the requirement to use doubled joists underscores the importance of ensuring that structural integrity is maintained where loads are concentrated.