Waste Stacks and Vents

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GLG

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I have a 3" waste stack that serves a second floor bathroom with toilet, sink and shower. It appears that there is not a vent at this end of the house.
This stack is one of 3, 3" waste stacks. The stack in the center of the house goes to the roof and is a combo vent and waste drain for another bathroom in the center of the house. The third waste stack serves another bathroom at the other end of the house. There is another 2" vent located somewhat in the center of the house on an outside wall (back of house) that goes to the roof and disappears into the concrete slab in the basement, tying into a 4" horizontal waste line that eventually goes to the city sewer. The 4" drain exits the front side of the house.

Can bathrooms on a second floor not have a vent? I don't see any PVC pipes in the attic connecting to the 2 roof vents. This house was built in 1990.

Thank you for any help.
 

John Gayewski

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I have a 3" waste stack that serves a second floor bathroom with toilet, sink and shower. It appears that there is not a vent at this end of the house.
This stack is one of 3, 3" waste stacks. The stack in the center of the house goes to the roof and is a combo vent and waste drain for another bathroom in the center of the house. The third waste stack serves another bathroom at the other end of the house. There is another 2" vent located somewhat in the center of the house on an outside wall (back of house) that goes to the roof and disappears into the concrete slab in the basement, tying into a 4" horizontal waste line that eventually goes to the city sewer. The 4" drain exits the front side of the house.

Can bathrooms on a second floor not have a vent? I don't see any PVC pipes in the attic connecting to the 2 roof vents. This house was built in 1990.

Thank you for any help.
No. Every trap needs vented in one way or another. There are different way to get there.
 

Reach4

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Can bathrooms on a second floor not have a vent? I don't see any PVC pipes in the attic connecting to the 2 roof vents. This house was built in 1990.
MD uses IPC. An AAV (air admittance valve) could vent the lavatory, and the drain of the lavatory could continue down and wet-vent the rest of the bathroom. So yes, a bathroom could have no TTR (thru the roof) vent.

However with 2 roof vents thru the attic, it seems likely they vented that second story bathroom with the TTR vent.
 

Jeff H Young

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It would be functional if it had an AAV instead of vent through roof . Only Assume the question is why does it not have a vent seen from attic? There should be evidence of a AAV if it has one.
A lot "can " be done , some are ok some not so ok but anything is possible you can't see everything So unless you are experiencing a problem I wouldn't be overly concerned or start making holes in walls
 

GLG

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MD uses IPC. An AAV (air admittance valve) could vent the lavatory, and the drain of the lavatory could continue down and wet-vent the rest of the bathroom. So yes, a bathroom could have no TTR (thru the roof) vent.

However with 2 roof vents thru the attic, it seems likely they vented that second story bathroom with the TTR vent.
Where would the AAV be located? Again, in the attic, above the bathroom, there are no PVC pipes. Thank you.
 

Reach4

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Where would the AAV be located? Again, in the attic, above the bathroom, there are no PVC pipes. Thank you.
You have two vent pipes thru the roof, right? Are you saying those are something other than PVC? Or are you saying that there is no visible branching up there, but there may be branching off in the wall? Branching off in the wall is common.
 

GLG

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So I found some old pictures of the house I took when it was being built in 1990. I specifically took pictures of all the drain and vent pipes. The picture of the bathroom in question shows a 2" vent pipe running up to the attic. So I made a trip into the attic and found the 2" PVC buried in insulation that runs over to and ties into the 3" stack vent. I can't believe I never saw that 2" vent line. I re-insulated the attic about 5 years ago. Sorry for the false alarm on this and I really appreciate the feedback you all provided.
 
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