I'm in the process of trying to run some CAT6 and speaker wire at various places in my house. One of the things I'd like to do is run speaker wire in the living room to a wall plate behind my sofa, for the surround sound speakers. This is an exterior wall that runs parallel to the joists in the crawlspace below. Thus, it rests directly on an end joist. Running wire through it will require drilling up at an angle through the joist, creating a diagonal hole or what may wind up being a notch.
I've found previous discussions of this issue, such as this one on this very forum,, or this one on another forum, where people say it's OK to do this through a rim joist (aka band joist.) However, I'm given to understand that the term "rim" or "band" joist refers specifically to the joist at the end that is perpendicular to the other joists and which they butt into, whereas the joists at the end that are parallel to the other joists are called "end" joists. Now, the logic by which this is said to be OK is that the rim joist is continuously supported by the foundation wall, so the segment you'd be drilling into, between studs, is not really bearing any weight or tension. But in my case, the end joist I want to drill through is also continuously supported by the foundation wall, so I don't see why the same logic wouldn't apply.
Furthermore, the builder has already done this, having drilled a diagonal hole here and there at points in this joist to run romex for power outlets along the exterior wall. I would just like to drill a somewhat larger hole (1 1/8") to accommodate ENT conduit. Can anyone comment on whether this would be OK?
Best Answer
It would be ok to notch or drill the end of the joist on a supporting member. Keep it in the middle or top section, not the bottom where it is bearing.
Rim joists DO bear load in many cases, however, drilling holes will not significantly downgrade the ability to carry that load and therefore it's ok. HOWEVER, rim joists on the second level or higher can be part of the lateral system and at most remove 1/3 of the depth and in the middle of the rim joist