Vent sizing?

[LO]

I plan to tie a number of vents into one 3†roof vent in a second floor remodel job. I have a long horizontal vent run to the roof vent (18’ long with a small slope, of course) above the ceiling where all the other vents will tie into. All the vents that tie into this horizontal vent run are 1 ½â€. Starting at the far right end and moving left toward the roof vent I have a washer vent, then a half bath vent (WC and Lav), then a full bath vent for a WC and Lav (shower vent comes later), then a vent that comes from the top of the vertical stack that drains all the above (washer,half bath, full bath) to the basement, then the full bath shower vent. Can the long horizontal vent be 1 ½†also or should I increase its size at some point along its horizontal run as the vents tie into it?

 

[Terry]

The toilet vents need to be at least 2"

So as soon as you tie in the first toilet, it needs to be 2" or more.
You can run three bathroom sets on 2", and then you need to bump the vent to 3"

However, you are only allowed to have 1/3 of the vertical as horizontal or it needs to be bumped up a size.

 

[Sponsor]

 

[Construct30]

Some codes say the vent or vents combined through the roof must have the same area as the main drain.

 

[TMB9862]

Since when do toilet vents need to be 2"? I've always been told they only need to be 1 1/2 and I've watched many of them in 1 1/2 pass inspection. Of course as soon as a second fixture is picked up it goes to 2".

 

[Terry]

Since when do toilet vents need to be 2"?

It depends on where you plumb.
UPC requires the 2"
And with new toilet designs, I'm starting to question whether that is enough.
Since flushes are much quicker now, it puts more onto the vents.
A back to back toilet installation can pull water from the bowl on the other side of the fixture cross.

 

[Construct30]

Terry is right about the 2" barely being enough. I've seen the 1 1/2" on old work, but would never do it when I replumb.

 

[Basement_Lurker]

It depends on where you plumb.
UPC requires the 2"
And with new toilet designs, I'm starting to question whether that is enough.
Since flushes are much quicker now, it puts more onto the vents.
A back to back toilet installation can pull water from the bowl on the other side of the fixture cross.

Ahh, thank you once again Mr. Love. I was contemplating if a 3" vent stack for a bathroom group was overkill if I didn't reduce it though the roof, but it seems according to your post that the benefit might offset the "eyesore" factor.

 

[Krow]

It depends on where you plumb.
UPC requires the 2"
.

Ontario plumbing codes require 1 1/2" minimum for WC.

1 1/2 vent can supply 1wc, 1 basin, 1 bathtub , 1 shower and 1 kitchen sink all at the same time

Each local will have a different requirement for minimum vent sizing

 

[Basement_Lurker]

Ontario plumbing codes require 1 1/2" minimum for WC.

1 1/2 vent can supply 1wc, 1 basin, 1 bathtub , 1 shower and 1 kitchen sink all at the same time

Don't you guys in Ontario have to bump up the sizing of your vents due to the frost factor in your harsh winters? My BC code even has a provision when dealing with frost, but it's not an issue since I live in the mildest place in the country.

 

[Mikey]

In Rochester, NY, they required a 4" vent, because of frost-buildup reasons. I'd be surprised if Ontario didn't have a similar requirement.

 

[Krow]

Don't you guys in Ontario have to bump up the sizing of your vents due to the frost factor in your harsh winters? My BC code even has a provision when dealing with frost, but it's not an issue since I live in the mildest place in the country.

For some reason the minimum requirement for a vent stack in Ontario is 3" penetrating through the roof and 6" minimum above roof (I would definetly agree with you guys about the frost build up, but thats what the inspectors expect to see in newer homes.)
I could never understand that part of the code.. 4" is still allowed but most contractors will stick with 3" because of cost difference, and it will be easier to embed the 3" pipe within a 2x4 wall. With a 4" pipe that will need to have a 2x6 wall to get it all hidden.

 

[TorontoTim]

Out of curiousity, when it says 6" above 'roof', what is defined as the roof? Does it just mean through the point it penetrates to open air, or is it in relation to other points on the roof also?

Our main stack exits the bathroom ceiling which is on the second floor. There is a third floor however, with no plumbing. The third floor isn't as deep as the second, so there is a sloped section of roofing that goes down steeply with a small (tiny) dormer, and then the slope becomes less steep and that's the roof over the bath where the stack exits.

Does the stack need to extend past the roofline of the third floor? If not, how close can it be to a window on the third floor?

This is in Toronto.

 

[Krow]

Out of curiousity, when it says 6" above 'roof', what is defined as the roof? Does it just mean through the point it penetrates to open air, or is it in relation to other points on the roof also?

Our main stack exits the bathroom ceiling which is on the second floor. There is a third floor however, with no plumbing. The third floor isn't as deep as the second, so there is a sloped section of roofing that goes down steeply with a small (tiny) dormer, and then the slope becomes less steep and that's the roof over the bath where the stack exits.

Does the stack need to extend past the roofline of the third floor? If not, how close can it be to a window on the third floor?

This is in Toronto.

In Toronto, Your case is a little different.

6" above roof means above the roof flashing on the shingles or flat roof.

In your case, if the dormer has a window that can open or any place that fresh air can enter the room, the vent has to be at least 12' away or 3' above the window or fresh air intake.

If you have a window that does not open and is sealed , than you are only required to be 6" above the shingles with the proper roof flashing around the pipe.

In the case that there is a roof top deck (downtown Toronto has a few), the vent needs to terminate a minimum 7' above the deck

 

[Winslow]

The toilet vents need to be at least 2"

So as soon as you tie in the first toilet, it needs to be 2" or more.
You can run three bathroom sets on 2", and then you need to bump the vent to 3"

However, you are only allowed to have 1/3 of the vertical as horizontal or it needs to be bumped up a size.

Depends on where he is located. Mass allows a 11/2 vent for the toilet if the trap arm is 3 inches.

According to the UPC 1/3 of the max allowable lenth may be horizontal. max lenth for a 11/2 vent is 60 ft so 20 ft can be horizontal. Max lenth of a 2 vent is 120 ft so 40 ft may be horizontal. Can't remember off hand about 3 as it isn't usually an issue.

Of course this all depends on what jurisdiction you are in and local code ammendments, along with the inspector(s).

 

[Mikey]

4" is still allowed but most contractors will stick with 3" because of cost difference, and it will be easier to embed the 3" pipe within a 2x4 wall.

In Rochester, they allowed 3" pipe inside the house, with a transition to 4" through the roof. I've forgotten how far into the house the 4" had to go.

 

[TorontoTim]

In Toronto, Your case is a little different.

6" above roof means above the roof flashing on the shingles or flat roof.

In your case, if the dormer has a window that can open or any place that fresh air can enter the room, the vent has to be at least 12' away or 3' above the window or fresh air intake.

If you have a window that does not open and is sealed , than you are only required to be 6" above the shingles with the proper roof flashing around the pipe.

In the case that there is a roof top deck (downtown Toronto has a few), the vent needs to terminate a minimum 7' above the deck

Thanks for the detail - looks like I need to add some height to the stack! The dormer is tiny, and the window rarely opened (about a 10 x 9 opening in the window max) but it is there, and only about 7 feet from the stack.

So the next question would be is there any specific method or code requirement for securing a vent that extends about 5 feet up from the roof?

 

[Jadnashua]

Do you have an attic with decent access? The pipe can take a turn and exit higher on the roof so it may not have to stick up as high unsupported.

 

[Krow]

So the next question would be is there any specific method or code requirement for securing a vent that extends about 5 feet up from the roof?

You have 3 choices.

1) you can offset the existing stack with 45 degree elbows (1/8 bends ) toward the side of the domer and fasten it there

2)if its too high and off setting is not an option, you canmount 2 braces half up the vent and mount the other ends to the roof. ( this may be over kill in some cases)

3) If its not very high of an extension, just install a no-hub for cast iron or glue a coupling on the ABS and leave it as is