Loop vent calculation

Old 05-11-20, 01:47 PM
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Join Date: Jun 2014
Location: Canada
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Loop vent calculation

Is there a calculation for how long a loop vent has to be?
I need to vent a 2" bathroom sink but the line then goes into a 4" drain from the roof and toilet goes into that as well.
Can this be done with a loop vent for both fixtures or does the sink need its own 1.5" loop vent?

Here is an example of what the plumbers did to vent the shower: Loop vent
The only vent is a wet vent/main stack on the roof. This is one option they in how they plumb houses in a remodel situation.
Old 05-12-20, 09:53 AM
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Sorry, I've never heard of a loop vent being used anywhere other than a kitchen island. When discussing loop vents in general, the code statement is something along the lines of "as high as practically possible".

My understanding is that loop vents require a cleanout on the 'drain' side of the loop also, so you may need to add a cleanout and access panel.

There may be local requirements in play too. Also my (limited) knowledge of codes are UPC and IPC, which are likely slightly different from Canadian plumbing codes.

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