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Are there any structural concerns for notching or drilling into the 2x4s nailed flat across the bottom chords of roof trusses? If so, is there a way to reinforce them?

I'm trying to run a 1/2" metal flex conduit between a switch box and bathroom fan, but the indoor wall top plate is right under one of the two 2x4s in question.

1/2" Conduit would require minimum 3 inch bend radius. I think there may be enough vertical clearance as long as I can drill a properly sized hole (IIRC bottom chords should be taller than 3 inches), it appears that drilling through top plate will be difficult without opening up additional drywall or notching/drilling those studs.

touko
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That board is known colloquially as the "rat run". It's often specified by the truss engineer to stabilize those bottom chord positions, and it provides a good anchoring base for the diagonal braces often installed on gable trusses.

I would consider normal stud notch/bore rules appropriate for that member (up to one third of the stud, if I recall correctly), but you could also just add another board alongside if you need to cut out more, lapping at least four truss chords, and nail it down properly. It's not critical that it be one continuous board.

isherwood
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From your description, It sounds as if you are looking at blocking across the bottom chord of trusses that is there just to give something for the partition wall to be nailed to.

If that is the case, then drilling or notching is no problem.

Pics, if possible, would give a definite perspective.

RMDman
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