# Ontario Building Code or National Building Code-Questions re:building drain size



## markb

Through all my apprentiship training and code book studying I have not been able to find any codes against what I am trying to do.


My building drain went to the middle of the home 4" to my 4"x3" c/o to open air. I then continued 3" underground to pick up a 3 piece bathroom. On this 3" branch, I connected a 2" pipe w/C/O, to pick up a kitchen sink on the second floor. 

Inspector says that I need to run 4" to my kitchen sink connection ( I.e. 4x2 c/o) because the drain is passing through one floor.


I don't see a need to run 4" pipe just for a kitchen sink on the second floor, but he insists that all pipes having a drain from the floor above must be 4" underground. 

I am looking for any code references (preferably OBC 2006, or NPC) that can help me explain to him my point. Was this a code requirement years ago and maybe he is not aware of the code changes?


----------



## AKdaplumba

National code is what I use. 

You need a 4" c/o on the farthest stack from the sewer( where it enters the house) If you have a pic it would be helpful and your saying you're coming in the middle of the house.

Or for your kitchen stack, run 4" to your c/o 4x3 c/o 3x2 bushing run 2" to the kit. Never heard of anyone needing 4" going to a second floor to pic up 1.5 FU.

send me a pic and Im sure I can help you out.


----------



## markb

http://photos-f.ak.fbcdn.net/hphotos-ak-snc3/hs196.snc3/20367_307099592586_504092586_3971367_1767020_n.jpgHere is the link to a drawing.

Was there some old old code that said you had to do this? The inspector is a old grumpy man. He once said that I couldn't wet vent two basins (two ty's ontop of one another) and told me that circuit venting can not be installed with 1 1/2 circuit and relief vents!


----------



## markb

... lol just remembered this one...

He once offered some "advice" on some sump pits I installed. He said to use a TY (as a saitary T) instead of a 90 inside of the pit. That way you get better flow because you vent the pit...Some of these city guys I just don't know about lol


----------



## A Good Plumber

Mark,
If I understand it correctly, I agree with the inspector.

We use the Uniform Plumbing code here and it says you need to have an end of line CO that is full size. In your case you would need to extend the 4" like the inspector says to the kitchen riser. You then install an accessible full size 4" CO at which point you reduce the vertical riser to 2" to pick up the sink.


----------



## markb

doesn't that sounds a little bit over kill though? If I didn't have the kitchen sink there, the branch would continue to be 3" right? (in your code). or would you continue it 4" and then branch off 3" for the bathroom.


----------



## AKdaplumba

I agree with the inspector. 4"c/o to the farthest stack for the building drain. From there you bush down to 2".

The existing is wrong by todays code.


----------



## AKdaplumba

if the kitchen wasnt there the 4x3 c/o would be fine where it is. 4" wye, bush the end to 3" to pick up the bathroom. 

Just understand farthest stack if your 4" c/o


----------



## Miguel

I'd have to go with the inspector on htis too, if I'm understanding your drwg correctly. (Where you show 4x3 c/o's I assume they are all stacks to be fitted w/ 3" cleanouts?)

Depending on the room you have, if you could get 45° (or less) change of direction to the first stack then 4" right to the base w/ 4" CO. Then simply run a 3" branch to the basement bathroom group and an 1-1/2" (or 2" if it's req'd by municipality - it is here) to pickup the KS on the floor above.

Cleanouts must be same size as the pipe they serve (downstream) to max 4". (ie: you could put a 4" CO on a 6" building drain, but NOT a 3" CO on a 4" BD.)

Also, watch for backflood protection. If required there, or you were going to use it anyway, they need accessible cleanouts too.


----------



## OldSchool

From your description even though a little not clear seems that you have done it right. 4" to main building stack with 4' clean out at base of stack then min 3" depending on whats above. Ground work can be 3" to basement washroom and 2" line to base of kitchen stack with 2" line clean out at base of stack. That inspector is a little confused as there is one main stack and all others are just stacks plumbed in size according to fixture units. The code has not changed much form the original ontario plumbing code.


----------



## AKdaplumba

OldSchool said:


> From your description even though a little not clear seems that you have done it right. 4" to main building stack with 4' clean out at base of stack then min 3" depending on whats above. Ground work can be 3" to basement washroom and 2" line to base of kitchen stack with 2" line clean out at base of stack. That inspector is a little confused as there is one main stack and all others are just stacks plumbed in size according to fixture units. The code has not changed much form the original ontario plumbing code.


I thought of one job site later on,a duplex(all duplexes), to the second unit there was a 4x3 wye, 4x3 c/o5 ft away off the end of the wye. the 3" branch off the wye picked up a P.R., bar sink and the basement bathroom. So technically the P.R. should be the 4x3 c/o since its farther. 

In either case run it to the farthest so you pass the first time everytime.

Lots of grey area's


----------



## Miguel

Not so much a grey area if there's only one building drain. 4" to the main stack (3" min no more than 45° offset and terminating at the roof) and a 4" CO at the base of that stack.


----------



## markb

Cut out the old plumbing and re-ran some of the pipes today. 

I suppose I agree with the inspector to a certain extent. That way the underground is always able to be fully cleaned. Trying to snake 4" underground is alot easier than trying to properly clean 2" underground. 

Anyways, thanks everyone. I know it wasn't too clear of a post (it was a bit late), but thanks for your thoughts. 

...still no code references though. Interesting. Maybe it's just one of those things everyone does and is inspector in forced, but not written in the code.

BTW, any Ontario plumbers here members of the OPIA? (Ontario Plumbing Inspectors Association)? I thought about becoming a member just for access to their forum. Hopefully to be able to ask inspectors questions regarding things like this. Anyone have any comments about the association and what they have to offer?


----------



## OldSchool

markb said:


> Cut out the old plumbing and re-ran some of the pipes today.
> 
> I suppose I agree with the inspector to a certain extent. That way the underground is always able to be fully cleaned. Trying to snake 4" underground is alot easier than trying to properly clean 2" underground.
> 
> Anyways, thanks everyone. I know it wasn't too clear of a post (it was a bit late), but thanks for your thoughts.
> 
> ...still no code references though. Interesting. Maybe it's just one of those things everyone does and is inspector in forced, but not written in the code.
> 
> BTW, any Ontario plumbers here members of the OPIA? (Ontario Plumbing Inspectors Association)? I thought about becoming a member just for access to their forum. Hopefully to be able to ask inspectors questions regarding things like this. Anyone have any comments about the association and what they have to offer?


That inspector has to rethink about over sizing pipe. It is not good to over size pipe such as running a kitchen drain using a 4" on the horizontal. Over sizing a pipe for a particular fixture will eventually clog the pipe. I have come a cross numerous 4" pipe in commercial that had been altered (renovated handled washrooms before) to only handle one sink. The pipes was completly blocked over its entire run.


----------



## Miguel

OldSchool said:


> That inspector has to rethink about over sizing pipe. It is not good to over size pipe such as running a kitchen drain using a 4" on the horizontal. Over sizing a pipe for a particular fixture will eventually clog the pipe. I have come a cross numerous 4" pipe in commercial that had be altered (renovated handled washrooms before) to only handle one sink. The pipes was completly blocked over its entire run.


That's a really good point which led me to assume that it was a building drain issue.
Code references would be:
*7.4.9.4*
*7.4.7.2*
*7.4.7.1*


----------



## jeffreyplumber

All you need to do is branch off before the end of the 4 inch with a 4x2 y then you will only need a 2 inch clean out. Im assuming you have a 4 inch cleanout in the middle of your house (End of Line). You might not need a c/o at all on the 2 inch since its serving the up stair as long as its less than 5 ft to main (horizontaly). Thats UPC code


----------



## markb

Miguel said:


> That's a really good point which led me to assume that it was a building drain issue.
> Code references would be:
> *7.4.9.4*
> *7.4.7.2*
> *7.4.7.1*





Code:




Interesting posts...

So here is my conclusion, and the inspector will hear about it next job

Nowhere in the Ontario building code does it state that all sanitary or waste stacks are required to be 4" at the base of the stack.

The Ontario Building Code 2006 does state that: 

- A building drain must be 4" * Note 1 * 

- A building drain begins at the building sewer and ends at our main soil stack (3" min to open air, most upstream soil stack from building sewer) * Note 2 *

- OBC states that every soil or waste stack be provided with a cleanout fitting *Note 3*

- Although it was previously thought of as safer while designing a plumbing system, NOT all underground should be 4". In fact, it is for the benefit of the system to size drains relative to the discharge it will receive using the tables included in OBC Part 7. *Note 4* 

- A clean-out is required to be the same size as the discharge pipe, installed every 6 M on drainage piping smaller than 4" and carrying the discharge from a kitchen sink *Note 5*

Therefore, as long as the stack has the required clean-outs and sized according to table 7.4.10.6.A (Maximum permitted hydraulic loads drained into a soil or waste stack, Forming part of sentence 7.4.10.6(1)) it has met the requirements of the Ontario Building Code and can be installed legally. 


References
Note 1: 7.4.9.4 (1) Every sanitary building drain and every sanitary building sewer shall be at least 4" in size

Note 2: (OBC Part 1 (definitions), sanitary building drain) Sanitary Building Drain: means a building drain that conducts sewage to a building sewer from the most upstream soil or waste stack, branch or fixture drain serving a water closet. 
As long as a stack is not serving water closets, there is no way that they can even be considered part of the sanitary building drain. Thus, they are NOT required to be 4" underground.

Note 3: 7.4.7.1 (7) Every soil or waste stack shall be provided with a clean-out fitting 
a) At the bottom of the stack
b) Not more than 1000mm upstream of the bottom of the stack, or
c) on a Y fitting connecting the stack to the building drain or branch
Note 4: “Years ago it was common practice to install drainage piping larger than necessary on the assumption that this would increase the efficiency of the drain. It was later realized that an oversized drain tends to be less efficient because the flow of water is too shallow to properly transport solids and also because it fails to provide the scouring action so important in keeping a drain clear.” Ontario Plumbing apprenticeship basic level manual, October 2006, page 277 

Note 5: 7.4.7.2 (1) (a) ...The minimum size clean-out opening shall be the same size as the drainage pipe...in the case of a sink waste pipe [cleanouts shall be spaced no further than] 6M apart
Mark Bajcar


----------



## Miguel

Aye! I think you've got it! :yes:

Prolly no need to make sure "the inspector hears of it" unless you intend to be tactful and _calm, submissive_. (Like the Dog Whisperer says. You might be more right than them but no point in showing it. They wield a big axe!)

Hope the job works out well!


----------



## jeffreyplumber

Our plumbing system is a lot differant than yours, we often times dont have a main stack, the new houses are all cut up there might be 3 bathrooms in different parts of the house with only a 2 inch vent serving each one, No main 3 or 4 inch stack, only old houses with all the plumbing grouped close by have a stack over 2 inch. 
So out of your code what is the conclusion , Inspector was right or wrong?


----------



## markb

Conclusion, the inspector was trying to be a know-it-all and add his own requirements to the building code.


----------



## CTC-OPIA

Hello,

You are correct, the stack to the kitchen need not be 4". The Ontario Building Code is very restrictive and has evolved. At one time it was required to be the furthest stack. Now its the furthest served by a water closet. Next time make the inspector write it up, then they have to find in the code where it states what they want. We have many inspectors now that have not be trained as plumbers inspecting plumbing. May refer to them as "one week wonders" because that is all the training they have had in plumbing.

Ciao,



markb said:


> Interesting posts...
> 
> So here is my conclusion, and the inspector will hear about it next job
> 
> Nowhere in the Ontario building code does it state that all sanitary or waste stacks are required to be 4" at the base of the stack.
> 
> The Ontario Building Code 2006 does state that:
> 
> - A building drain must be 4" * Note 1 *
> 
> - A building drain begins at the building sewer and ends at our main soil stack (3" min to open air, most upstream soil stack from building sewer) * Note 2 *
> 
> - OBC states that every soil or waste stack be provided with a cleanout fitting *Note 3*
> 
> - Although it was previously thought of as safer while designing a plumbing system, NOT all underground should be 4". In fact, it is for the benefit of the system to size drains relative to the discharge it will receive using the tables included in OBC Part 7. *Note 4*
> 
> - A clean-out is required to be the same size as the discharge pipe, installed every 6 M on drainage piping smaller than 4" and carrying the discharge from a kitchen sink *Note 5*
> 
> Therefore, as long as the stack has the required clean-outs and sized according to table 7.4.10.6.A (Maximum permitted hydraulic loads drained into a soil or waste stack, Forming part of sentence 7.4.10.6(1)) it has met the requirements of the Ontario Building Code and can be installed legally.
> 
> 
> References
> Note 1: 7.4.9.4 (1) Every sanitary building drain and every sanitary building sewer shall be at least 4" in size
> 
> Note 2: (OBC Part 1 (definitions), sanitary building drain) Sanitary Building Drain: means a building drain that conducts sewage to a building sewer from the most upstream soil or waste stack, branch or fixture drain serving a water closet.
> As long as a stack is not serving water closets, there is no way that they can even be considered part of the sanitary building drain. Thus, they are NOT required to be 4" underground.
> 
> Note 3: 7.4.7.1 (7) Every soil or waste stack shall be provided with a clean-out fitting
> a) At the bottom of the stack
> b) Not more than 1000mm upstream of the bottom of the stack, or
> c) on a Y fitting connecting the stack to the building drain or branch
> Note 4: “Years ago it was common practice to install drainage piping larger than necessary on the assumption that this would increase the efficiency of the drain. It was later realized that an oversized drain tends to be less efficient because the flow of water is too shallow to properly transport solids and also because it fails to provide the scouring action so important in keeping a drain clear.” Ontario Plumbing apprenticeship basic level manual, October 2006, page 277
> 
> Note 5: 7.4.7.2 (1) (a) ...The minimum size clean-out opening shall be the same size as the drainage pipe...in the case of a sink waste pipe [cleanouts shall be spaced no further than] 6M apart
> Mark Bajcar


----------



## AKdaplumba

How do you define "main stack" most load? most toilets?


----------



## evilcyrus

Furthest stack from street is main stack.. end of run. (most up stream) from what i understand . according to your sketch the inspector is right .. furthest stack has to be 4".


----------



## CTC-OPIA

In Ontario there is no definition of "Main Stack". The Sanitary Building Drain only must be 4" and ends at it's upstream end into a soil or waste stack served by a water closet, then if one is not available you can use a vent stack or waste stack (found in the body if the OBC2006), then if those are not available you move on to a branch or furthest fixture drain, this found in the definitions, which came from the National Plunbing Code of Canada during harmonization of the codes. In Ontario soil stacks and waste stack are defined separately. In the National Plumcibg Code of Canada there is only one definition - "soil-or-waste stack". No where does it state just the furthest stack or main stack.


----------



## MxNut

*Building drain*

Should The building drain be the furthest stack? If I have a powderoom on the first floor and two bathrooms on the second floor,all three at the front of the house, but have a two piece roughing at the back of the house in the basement.
I am not going to run a 4 inch to the powderoom then vent my main stack all alone from the basement to open air. 

If a river conducts water from the most upstream creek to the ocean, is the furthest creek the river? Not.
All the code means is the building drain conducts sanitary from the most upstream connection to the building sewer. It does not say that the building sewer IS the most upstream connection. 

And if i am wrong , this means that as plumbers we are considered stupid.
We should be able to design our system according to the house. By telling me go to the furthest sanitary is making me nothing more than a cookie cutter plumber.


----------



## OldSchool

jeffreyplumber said:


> Our plumbing system is a lot differant than yours, we often times dont have a main stack, the new houses are all cut up there might be 3 bathrooms in different parts of the house with only a 2 inch vent serving each one, No main 3 or 4 inch stack, only old houses with all the plumbing grouped close by have a stack over 2 inch.
> So out of your code what is the conclusion , Inspector was right or wrong?


We need at least a one 3" main vent stack..... any other vent penetrating the roof must be 3" this is required because of frost (any smaller vent pipe will freeze up with frost) ..... we are allowed to bring what ever size in the the attic but must increase vent size to 3" as we pass thru roof.


----------



## MxNut

*Building drain*

We need 1, 3 inch stack going through the roof from the building drain. That is a no brainer. What the problem is that some say it has to be the most upstream sanitary. My upmost upstream sanitary may only be picking up a powderoom. If I want to end the building drain( my 4 inch) at a point in the middle of the house because that is where it goes up to serve 2 bathrooms then so be it. If in the back of the house there is a powderoom then I branch a 3 inch off the building drain to serve that.


----------



## MxNut

CTC OPIA your note 2 includes the words "or waste stack" that means a non sanitary stack. So by definition if my most upstream stack is a waste stack it must be designated as my building drain and therefore 4 inch.
This is where the interpretation of the definition is all wrong. All it means is that the building drain, drains sanitary stacks, waste stacks, branches and toilet fixture drains, from the umost upstream connection to itself then to the building sewer. Because the building drain by definition is horizontal only, all the definition means is that the building drain picks up all the branches( stacks or other) that are horizontal (or underground) and conveys them to the building sewer.
So i can designate any stack as my building drain as long as it conforms... 4 inch to the base, 3 inch to open air.


----------



## CTC-OPIA

The reason I stated "soil-or-waste stack" is because whe the codes across Canada did their so called "harmonization" - only Ontario defines a soil stack and waste stack separately and the definition in the OBC2006 uses the National Plumbing code of Canada's definition.

The main question is that does the sanitary building drain end in a soil-or-waste stack, yes - 3" to open air, does it need to be the powder room at the back of the house instead of the soil stack receiving two bathrooms at the front of the house - not any more.


----------



## MxNut

*building drain*

I agree with you , the problem I am having is we have an inspector who wants the building drain at the most upstream stack. Its totally illogical.


----------



## rogeru

From you description I agree with *markb*. I think the inspector is a little confused. In my opinion the branch can be the size for the fixtures it is serving. Every building requires at least 1-4" building drain and 1-3" stack passing thru the building. It could be a vent stack,soil stack or waste stack as long as it is 3". Where the building drain comes thru the floor it needs to be maintained at 4" with a 4" cleanout to serve this 4" building drain. From that point on it can be reduced to 3". What has happened over the years I believe it was easier to give the drainman 4" pipe for everything below grade. Not a problem for them to figure out anything as 4" pipe to all branches would work especially in residential construction. Some inspectors have seen so much 4" pipe they think it is code. 
rogeru


----------



## Miguel

Really? You ressurected this from the depths?
Yeah, I still find myself going over where to best place the main stack. Rule still is that every building drain must terminate in a 3 " stack. Even better, the new wording for vent terminals has many municipalities expecting an increase to 4" before leaving the roof line!

Ont Code *7.5.6.5.*
_*(6) *Where a vent pipe passes through a roof or an outside wall of a building, it shall be protected from frost closure by increasing it's diameter at least one size, but not less than 3 in. in size, immediately before it penetrates the roof or the wall._


----------



## nadroj26

4" c/o to furthest stack serving a w.c


----------

