[mismel8]

We've been living in a house for 3 years and have been doing some remodeling throughout. It appears that there is no venting system in the house. There are 3 toilets, 4 sinks, and 2 showers, however we cannot find a vent stack anywhere. My roofer noticed this when he took off the old roof - he found that there were pipes coming out the roof, but they weren't attached to anything in the attic. I once had a plumber look around, and he couldn't find any vents in the attic. We have also searched the attic extensively within a 5-foot radius of each toilet, and found nothing. Is it possible that my house has no vent system? It was built in 1959 and an addition (including 2 bathrooms and a new kitchen) was built in 1974 (I should mention that the addition was built by people who seemed to cut corners in every way possible), and the house is on the city sewer system. All of the fixtures in the house seem to drain fine, but it seems that many people believe that this would be impossible without a proper venting system. Also, the (1 inch) drain for the washing machine in the garage sits loosely in a 2 inch PVC pipe just sticking out of the ground - I don't see a trap, and if you listen closely to the pipe, you can hear water moving when someone is showering/flushing a toilet. I suppose you could call this a type of vent. But, there are no strange smells anywhere. Finally, we also can't find a cleanout anywhere outside of the house. Given the year the house was built/remodeled, should it have one?

[speedball1]

we also can't find a cleanout anywhere outside of the house. Given the year the house was built/remodeled, should it have one?

Yes! Code mandates that a house cleanout be installed not over 18" from the foundation and brought to grade.

We have also searched the attic extensively within a 5-foot radius of each toilet, and found nothing. Is it possible that my house has no vent system? It was built in 1959 and an addition (including 2 bathrooms and a new kitchen) was built in 1974 (I should mention that the addition was built by people who seemed to cut corners in every way possible),

Houses built in the 50's all have vents installed. You sound like your house was built with vents but they were eliminated when the former owners remodeled. This must have been done by the owners thenselves as I can't believe any plumber would leave a job in the shape that yours was left in.
Did you have your house inspected before you bought?

the (1 inch) drain for the washing machine in the garage sits loosely in a 2 inch PVC pipe just sticking out of the ground - I don't see a trap, and if you listen closely to the pipe, you can hear water moving when someone is showering/flushing a toilet. I suppose you could call this a type of vent

NO YOU COULDN"T!! call this a "vent". This sounds like a diurect open connection between you house and the city sewer allowing sewer gas to enter your home. This is a health hazard to your family and should be corrected at once.

All of the fixtures in the house seem to drain fine, but it seems that many people believe that this would be impossible without a proper venting system.

And here's where you must make a major decision. Back in the 40's when I started plumbing none of the older homes were vented and they drained just fine. I'm a great believer in: If it ain't broke don't fix it! I would get a trap installed on the washer stand pipe ASAP but it's going to be your decision about changing those "S" traps over to "P" traps ans adding vents. Good luck in whatever you decide, Tom

[mismel8]

Tom, thanks for your quick response. I think you are probably right that the former owners eliminated the vents when they remodeled; it is consistent with many other things that they did wrong. The strange thing is, when they remodeled, they reused the old plumbing (and unfortunately for us, they left in a few feet of cast iron in 2 spots, while using PVC everywhere else - something we are dealing with now). In order to reuse the old kitchen plumbing, they dug a trench in the concrete to where the new shower was going and connected that to the old (cast iron) kitchen plumbing. Since that old plumbing was part of the original house, I would have expected it to have a vent, but apparently not. My new question is - given that there are no vents, does that mean all of our traps would be considered S-traps and not P-traps, since they basically all form an "S" without a vent coming off first? None of the traps have a siphoning effect sucking the water out, but it also appears that they added in 8-10 inch horizontal sections before they drop down into the floor - perhaps that is why? Regarding the cleanout, the city sewer is in the street in front of the house - does this mean the cleanout should be in front also? Is it possible that it is buried under the grass/plants/dirt? And, yes, the house was inspected before we bought it, and the inspector apparently didn't catch this (perhaps because there were pipes coming out of the roof, as if there were vents). And I suppose it was easy to miss the washer problem, because we didn't notice it until we opened up the wall. We will certainly get that fixed asap!

[speedball1]

My new question is - given that there are no vents, does that mean all of our traps would be considered S-traps and not P-traps, since they basically all form an "S" without a vent coming off first? None of the traps have a siphoning effect sucking the water out

mIt sure sounds like you have "S" traps. But they are traps,and they have worked for three years with no problems. As I've said, back in Wisconsin before we left I've seen plenty of homes with unvented traps that were trouble free. Not that I'm advocating "S" traps but it's going to cost a bundle to bring you up to code. This is your decision to make and all I'm doing is presenting facts.

Regarding the cleanout, the city sewer is in the street in front of the house - does this mean the cleanout should be in front also? Is it possible that it is buried under the grass/plants/dirt?

As a rule the cleanout's left alone when a remodel goes down. You should still have one. It's usually on the same side as the city sewer. When we look for one we take a pointy rod called a probe and jab around the house until we hit metal.
I would have the washer trapped ASAP If you don't wish to run a vent up you could install a AAV,(Air Admittance Vent) just downstream from the trap, (see image) Good luck, Tom

[mismel8]

Thanks again for your help. We will definitely get the washer trapped asap.