Looking for vent help on installing a new half bath

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Old 12-15-13, 08:11 PM
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Looking for vent help on installing a new half bath

I am looking to install a half bath on my first floor. My house currently only has 1 bathroom on the 2nd floor and all plumbing is going to the main stack. The new half bath will be 25' from the main stack so a new vent is going to be needed. I had 3 plumbers come to give estimates and I am comfortable with one of the plumbers. He was the only one who suggested putting the toilet on the furthest side (from the main stack) of the room than the sink so he can wet vent it. None of the others mentioned that. After research, it seems that he had good advice and is correct. Thats why I am here....

I have to install the toilet and sink and run drain to the main stack. I then have to vent from a 2" wet vent up to a 1.5" up then vertical 1.5-2' to the wall upstairs and the straight up to the attic, then out the roof.

-is this the best way?
-2" wet vent then 1.5", are these the correct sizes or do I need a 3" vent?


Any other questions to bring up, advice, or issues here? I want to be sure I know what to expect.

This plumber also recommended replacing the cast iron main section in the basement with PVC and adding a clean out. He is a family member so I know he's not looking to make things up here. NHL said it was up to me and after some thought, it might be a good idea. It's original to a house built in the 1930s but jot current issues (besides sloppy plumbing running into it from the kitchen).
 
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Old 12-16-13, 08:15 AM
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Also, my plumber is now saying that he can vent it as listed above but instead of going out the roof, he can tie into the main vent in the attic. Is there a certain distance to do this? It will have to travel about 15; straight across the attic floor. I think venting straight out the roof is a better option.
 
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Old 12-16-13, 04:43 PM
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He can tie into the stack as you show and need not go through roof.. When he ties in have him replace that section through the roof with PVC...



I always recommend replacing cast with PVC... Do as much as you can IMO.

I then have to vent from a 2" wet vent up to a 1.5" up then vertical 1.5-2' to the wall upstairs and the straight up to the attic, then out the roof.

Wet vents are illegal... possibly its your terminology...


basically like this.....grn is vent...can be 1 1/2 as well as sink arm..

Toilet 3"... Pipe from vent to toilet 3" must be 2".....





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Old 12-16-13, 08:38 PM
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Really no difference between tying into the existing vent in the attic or venting separately.

Tying into the same vent leaves only one roof penetration (and one less potential place for a leak). But it may take up some attic space depending on how it's run. It may also require the boot on the roof to be repaired/replaced depending on its age. Moving any of that piping may break the seals.

Creating a new vent requires making a new hole in the roof and properly sealing it. It's not hard, but you want to be sure it's done correctly so you don't get any future leaks.
 
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Old 12-17-13, 08:54 PM
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Wet vents are illegal? How do you recommend venting a sink and toilet? I'm sure it's my terminology but I want to be sure.
 
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Old 12-17-13, 09:03 PM
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How do you recommend venting a sink and toilet? I'm sure it's my terminology but I want to be sure.

Just like my diagram in post #3.................
 
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Old 12-17-13, 09:12 PM
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I see that and that's what I think a wet vent looks like. When I google wet vent, I get the same thing. But you know more than I do so when you say illegal, I look more into it.
 
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Old 12-17-13, 10:13 PM
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A wet vent is when no fixture arm is vented and the vent is dependent on the stack to vent... This will siphon water from the bottom trap when the upper fixture is used, This has been not to code for at least 25 plus yrs.........




Think like a trap... even though this says wet vent its not, and allowed by code because of branch vents... That lets the other fixtures use the branch vent and not siphon other traps......

Simple plumbing 101... But this is the hardest for non plumbers to understand...I do this in my sleep.........LOL


 
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Old 12-18-13, 06:40 AM
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Were on the same page here. Never seen the first pic before but I get why that's called a wet vent. I'm doing the 2nd pic. Thanks.
 
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