Maximum horizontal pipe diameter in load bearing (2x4) wall

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Ivan Blackford

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Hi All,

I apologize if this has been posted already, or if this is the wrong forum for this. My questions pertain specifically to the building codes and practices in Ontario, Canada.

I'm looking at running a horizontal vent pipe, 1.5" ID,~2" OD, through a load bearing 2x4 wall. Is this permitted? If it's not permitted, what are the common workarounds for this? If I can't go through the load bearing wall, can I pickup the vent pipe from the floor below and make a vent loop that goes above the flood line of my appliance?

Thanks in advance,
Ivan
 

wwhitney

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As least for the US, there's a difference in the rules between routing a pipe horizontally (through the studs) vs just vertically (through top and bottom plates only). So which do you mean?

And of course going vertically through a header or horizontally through a post carrying a point load would be a terrible idea and not allowed.

Cheers, Wayne
 

Ivan Blackford

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As least for the US, there's a difference in the rules between routing a pipe horizontally (through the studs) vs just vertically (through top and bottom plates only). So which do you mean?

And of course going vertically through a header or horizontally through a post carrying a point load would be a terrible idea and not allowed.

Cheers, Wayne
I would be going horizontally through the studs. My gut reaction is that it's not allowed, I just don't know how much is allowed. For instance, can I drill a 3/4" hole for supply side plumbing? Just as a thought experiment, if I were to replace the wall with say a 2x6 wall, would that then give me sufficient strength to allow me to bring my vent pipe through it?
 

wwhitney

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A little googling yield Ontario Building Code 9.23.5.3 https://www.buildingcode.online/1828.html

9.23.5.3. wall studs

(1) wall studs shall not be notched, drilled or otherwise damaged so that the undamaged portion of the stud is less than two-thirds the depth of the stud if the stud is loadbearing or 40 mm if the stud is non-loadbearing, unless the weakened studs are suitably reinforced.

So for a bearing 2x4 wall you can drill 3.5"/3 = 1.16" without concern. Large than that you need to "suitably reinforce" the studs. With a word like "suitably" it is presumably up to the building department/inspector to say what is suitable. In the US a reinforcement like Simpson HSS2-SDS1.5 would certainly be considered suitable.

Adjacent sections of the Ontario Building Code cover other framing members.

Cheers, Wayne

P.S. I see you do specify horizontal in your thread title, sorry I missed that.
 

Ivan Blackford

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It's been a while since I logged in, and I thought I should provide an update.

I ended up replacing the vertical copper branch vent with ABS, and tying into it above the kitchen cabinets, bringing my new connection through a non-structural bulkhead instead of trying to get it through a load bearing wall.

Interestingly enough, I found that the original sink drain (Copper, 1.5") was plumbed horizontally through the wall. This makes me question either the legality of what was done (it was done by the original builder, ~1960) or the makes me question how load bearing the wall actually is in that section. Regardless, my solution didn't compromise anything. :)
 
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