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Vent Intersection Height?

1K views 7 replies 3 participants last post by  ddawg16 
#1 ·
When the plans say

VENT INTERSECTION MUST BE
AT LEAST 6" ABOVE RIM OF
HIGHEST FIXTURE SERVED

In the case of a bathtub....does that mean above the rim of the bathtub or where the drain is?
 
#5 ·
The idea is that if the drain pipe becomes clogged and water backs up, it will flood over the rim of the highest fixture before it flows (and potentially clogs) horizontal vent pipes of other fixtures. For example: Assume you tied the tub vent horizontally into the vertical sink vent above the sink drain tee/trap, but below the rim of the sink. If the sink drain becomes clogged, the water will flow down the tub vent before it ever overflows the sink rim; which, in turn, could cause drainage and venting issues at the tub.

Typically the laundry box will be the highest point on any floor level that has a laundry connection, so if that's the case, the vent intersection should be 6" above that. If there's no laundry on that floor, then the highest fixture would typically be a lavatory/sink.
 
#6 ·
I figured as much.............

But.......

What about the second story? Which is where I'm working now.....If I have a blockage on the 1st floor and the wife is taking a bath......I see water coming out of a lot of places on the 1st floor....
 
#7 ·
I figured as much.............

But.......

What about the second story? Which is where I'm working now.....If I have a blockage on the 1st floor and the wife is taking a bath......I see water coming out of a lot of places on the 1st floor....
True. Nothing will change that. But as long as the vents are tied in properly, no water will find it's way into any horizontal vents.
 
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