[stardogFB]

In gathering online info in preparation for relocating my shower drain, my curiousity finally got the best of me and I suddenly found myself wanting to learn everything possible about how a normal home plumbing system works. Which leads to my question below.

Our single story house was built in 1960. When I was outside I took notice of all the vent stacks protruding thru the roof. I counted five: 2 were located above the front bathroom (I presume for the toilet, sink, and bathtub); and 3 were located above the rear bathroom (one over the toilet, one over the sink, and one over the standup shower). I didn't check the east side of the house, but I presume there is also one protruding over the kitchen sink and a separate one in the laundry room protruding over the washer drain.

Why so many separate vent stacks??? Is this just the way plumbing systems were designed back in the 1960's? It seems like overkill. Couldn't all the various vent lines be tied into just one or two main stacks? The reason I ask is that when I view plumbing "how to videos" many of them show a network of vent lines running thoughout a house, but yet only one or two stacks actually protruding from the roof.

Just asking out of curiousity and to become more knowledgeable. Tks.

 

[Old Thomas]

Today vents that are reasonably close to each other are connected together and the one vent terminal. It all slopes down so rain water goes down the drain.

 

[Nealtw]

Cast iron with lead filled joints, straight up would be labour friendly.

 

[TheEplumber]

@stardogFB every trap requires a vent. Every trap has a water seal between 2-4 inches. The vent must be large enough and located in certain spots so the trap seal is protected against positive/negative pressure.
The total combined cross secton area of your vents should equal or exceed the area of your building drain.

With exceptions, vents can be horizontal, vertical, wet, dry, single, common, etc....
Your roof could have multiple penatrations or just one. It depends on the fixture locations and other factors. I try to do one vent through the roof per bathroom group.
Hope that helps

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[Old Thomas]

In NY at least one vent stack has to be full sized and every vent terminal has to be at least 3”. If a vent is smaller than 3” it has to have a long increaser so it penetrates the roof as 3”.

 

[Ghostmaker]

Vents are actually more important in plumbing than the drain. Vents prevent your water seal on the traps from pulling and letting in sewer gas and the covid virus from the building sewer. Yes Covid moves in the sewers also.

 

[stardogFB]

Tks for all the replies. The answer from Nealtw probably hits the nail on the head. When doing some minor remoedlilng in the rear bathroom I did notice some of the vertical stacks are indeed cast iron. Back in the day I would probably agree it would be less labor intensive to simply stick in a vertical pipe wherever needed while the house was beng constructed.

Tks for everyone's insight, much appreciated per usual.