4 inch plumbing vent stack?

[BlueRidgeMark]

I've never seen this before. How about you?

I'm remodeling my bathroom. Stripped down to the studs. I just found the original builder used 4" PVC for a vent stack off the toilet.

WHY?? I'm not a builder, so I could be wrong on this, but I don't think code requires much more than 2" on a vent stack. Maybe 1 1/2"?

Why chop a top plate in two just to run 4"???

Oh, well, at least it's not a load bearing wall. It's been that way for longer than I've been here, so I guess it will stay that way.

 

[GG Woody]

There is a town around here that requires 4" *just* going through the roof, apparently the "hoarfrost" can plug a smaller vent.
Is this just venting the toilet? Not a macerating toilet or a sump? Must have been free pipe!

 

[BlueRidgeMark]

There is a town around here that requires 4" *just* going through the roof, apparently the "hoarfrost" can plug a smaller vent.
Is this just venting the toilet? Not a macerating toilet or a sump? Must have been free pipe!

Yeah, just a plain jane toilet. Lazy as these people were, I guess it was just what he had on hand. You would not believe some of the garbage I've run into.

How about an interior door "header" made of a single 2x4? Laid flat? Oh, and butted into the king stud on one end. No cripple stud to be found.

Why, yes, that was in a load bearing wall. Why do you ask?

 

[Whitenuckler]

I've never seen this before. How about you?

I'm remodeling my bathroom. Stripped down to the studs. I just found the original builder used 4" PVC for a vent stack off the toilet.

WHY?? I'm not a builder, so I could be wrong on this, but I don't think code requires much more than 2" on a vent stack. Maybe 1 1/2"?

Why chop a top plate in two just to run 4"???

Oh, well, at least it's not a load bearing wall. It's been that way for longer than I've been here, so I guess it will stay that way.


View attachment 340820

That is the main stack, and 4 inch should be used. The other fixture vents that join up are usually 1 1/2. Remember that stack might have multiple vents, and you don't want it to get plugged with snow ect. I have replaced cast iron pipe on one house. That's when you use a breaker. If you have any amount of new plumbing going in, go to ABS.

 

[BlueRidgeMark]

Interesting. It's just the toilet, shower, and bathroom sink. That needs a 4"? There's a kitchen and another bathroom, but they both have 1 1/2" vents of their own.

Snow can be stopped with a vent cover, or is that not allowed?

 

[bholler]

Interesting. It's just the toilet, shower, and bathroom sink. That needs a 4"? There's a kitchen and another bathroom, but they both have 1 1/2" vents of their own.

Snow can be stopped with a vent cover, or is that not allowed?

They often ice up in our area if we have single digit or below temps for to long. And yes for just a bathroom 4" is probably excessive. I usually ran 2" just for a bathroom. But there are formulas to figure out how big it needs to be.

 

[BlueRidgeMark]

Well, thanks for the feedback! 👍

It's always good to learn something new!

 

[Whitenuckler]

Interesting. It's just the toilet, shower, and bathroom sink. That needs a 4"? There's a kitchen and another bathroom, but they both have 1 1/2" vents of their own.

Snow can be stopped with a vent cover, or is that not allowed?

Sometimes it is not easy to vent your plumbing to the main vent, although in a new design it should be done that way. In additions ect, they may have to run a new vent up and out. The "cheater" vent has also been used. I stuck one up under my kitchen sink after the trap. You should not need to cover a vent, as it should have warm sewer air coming up all the time. Now a 1 1/2 may plug up a bit for awhile. I have never in my life seen a cover for a plumbing vent. Plumbing is actually very interesting. The codes may be different in the warmer zones too.