Maximum permissible size of holes through 2x4 studs?

[nostos156]

Wondering what the regs say on this, as I can't find information on it, just about joists. Googling gives me American standards saying you can drill up to 40% of a stud's width, even up to 60% if you double them. Other than that, I came across an apparent structural engineer saying up to 50mm in a 40x95mm stud is fine, but nothing clear-cut written in stone.

[George]

There's no hard and fast rule. 

 

If it isn't a load bearing wall then it just needs to be enough wood to hold itself up. 50% removal sounds fine for that. 

 

 

 

[Nickfromwales]

Is this one hole for a single ~50mm service, or do you need a transit for multiple cables / small bore pipes?

[nostos156]

11 hours ago, Nickfromwales said:

Is this one hole for a single ~50mm service, or do you need a transit for multiple cables / small bore pipes?

 

Single 40mm conduit (I could go 32mm but HDMI cables are a PITA), through a couple of studs. It's going into an interior wall in the attic space, so I can't get it in there unless I rip up floorboards and go from underneath. Going through the side would be easier if the holes are able to be bored.

 

Pretty sure it is not a load bearing wall as it's parallel with the joists above it.

Edited January 20, 2023 by nostos156