Adding 3 piece bathroom in the basement

[vikikiki]

I am looking into adding sink, shower and toilet in the basement. My house is 10 years old and the builder did not do rough-in. I have a bathroom on the first floor and it has 4" drain pipe going to the basement. I have two bathrooms on the second floor and each one has 4" drain pipe going to the basement. One of the drain pipes is a vent and goes up to the roof. The picture that I enclosed is showing this wet vent pipe. The rest of the picture is what I am thinking of doing to add these three fixtures. I am looking at adding AAV since there is no way that I can tie the vent to the second floor wet vent. What do you guys think about this? I live in Ontario and according to the code AAV are allowed. I read somewhere that if you are less than 6 feet away from the 3" wet vent that you do not need venting but I can not find that in the code.

Let me know.
Thanks
Peter

 

[vikikiki]

Anyone has any comments or suggestions if I am doing this right?
Thanks
Peter

 

[phishfood]

The problem I see with your proposed system is that there is no way to relieve pressure that can build up as the water drains down from the upper floors. That positive pressure can blow out the traps of the new fixtures in your basement That is one of the two issues I have with AAV's, The other issue that I have with AAV's is that they are a mechanical device, and as such, are prone to failure. Anotherwords, they can stick open or stick closed.

I think that the situation you have, with floors above draining down and then a bathroom attached in the basement, is probably the worst place to install an AAV. I would do whatever was necessary to get a real vent out to open air.

 

[vikikiki]

I appreciate your answer. I have never used these AAVs before so my lack of knowledge is frustrating me. The last resource would be drilling the hole through the basement wall for the vent and running the vent pipe along the outside wall next to downspout and up through the roof. BUT, last night I was looking around a little more and found 2” pipe that is draining the washing machine (laundry sink) from the first floor, running horizontally inside the basement about 4 feet and drains into another close by 4” drain. The 2” pipe has what it looks like a vent coming out from the horizontal run and goes up through the wall and I AM ASSUMING THIS PIPE IS CONNECTING TO THE VENT STACK SOMEWHERE UPSTAIRS. Tonight I have to see if this is a dry vent or wet. I would assume that laundry sink needs a vent as well. The house is 10years old so plumbing should have been done according to the code. I will start letting some water go down the drain from upstairs bathrooms and feel if any water is running through this pipe. I will let you know. Hopefully I can take a picture.
Thanks

 

[vikikiki]

No luck. There are two pipes connecting to 2" horizontal pipe that is draining a laundry sink. One of them is the drain for a bathtub from the second floor and the other one drains sink from the second floor. I am pretty much stuck. Tonight I will look in the laundry room on the first floor to see where the vent is connected to.