First time doing below slab drain plumbing, many questions

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Ivan Blackford

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Hi All,

This is my first time doing any major work below a concrete slab. I live in Ontario, and the home is in Ontario. I have the following:

8ecd2eb1-b878-4d41-8234-faf9d46a4ac4.jpeg

The total run length, from the intersection with the main drain to the end of the green segment is 25ft.
The White intersection is the main 3" drain going to the street.
The Green section of pipe will serve a new kitchen sink
The Blue section of pipe will serve a washing machine
The drain pipes are serving a basement kitchen/laundry area
This plumbing work will be inspected by the local municipality.
My questions:
-in Ontario, is it required to install a floor drain when doing the kind of work that I'm doing?
-What size should I use for each pipe section? I believe that I can use 2" pipe for the red and blue segments, while the green segment would be 1.5"
-Are there any limitations on bends in the pipe? I have to do a slight bend around the footings, and I would need to turn 22.5 or 45 degrees.
-What fittings should I use for the horizontal to horizontal runs? I think I need to use wyes in all cases.

Thanks in advance for any assistance!
 

John Gayewski

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Use 2" all of the way.

Not sure about a floor drain but a basement floor drain is generally a really good idea near a wall.

Wyes for branches and 22.5 for offsets.
 

breplum

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I concur 2" all the way, plus a cleanout at the kitchen.
I recommend you have a properly licensed contractor/plumber do the work.
Too many pitfalls for a newbie to do in a non-changeable situation. Proper support and backfill is vital.
 

Ivan Blackford

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I've done lots of above ground, inspected plumbing (with some assistance from this forum) so I'm not quite a newbie, I just haven't put it below a slab, so I want to know 100% that I'm getting it right! :)

in regards to the floor drain, if I were to add a branch for a floor drain, would it require the red section of pipe to be upsized to 3"? or is 2" still acceptable?

I plan to put a vertical cleanout at every point where the pipe comes up through the slab.

Thanks, Ivan
 

James Henry

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non-changeable situation. Proper support and backfill is vital. Proper grade is also extremely important. Do not take this lightly.
 

John Gayewski

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You don't need 3". But you'll want the floor drain to be upstream of the washer and the tie in's 10 feet apart if possible. The further the better you don't want sudsing for drain.
 

Sylvan

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Use 2" all of the way.

Not sure about a floor drain but a basement floor drain is generally a really good idea near a wall.

Wyes for branches and 22.5 for offsets.
John NYC min FD is 3" and now a washing machine discharge is 2" and has to increase to 3" once it goes underground
 

Ivan Blackford

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John NYC min FD is 3" and now a washing machine discharge is 2" and has to increase to 3" once it goes underground
This was my instinct, that I needed to go 3" underground. Can anyone confirm what the requirements are for ontario? What are the relevant sections of the OBC that I should review for this?

Thanks, Ivan
 

Ivan Blackford

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From what I can see from the OBC, the following applies to me:

1) As per OBC 7.1.4.2:
(1) Where gravity drainage to a sanitary drainage system is possible, a floor drain shall be installed in a basement forming part of a dwelling unit.

2) As per OBC 7.4.9.3: Washing Machine pipe size: 2", Floor drain: 2", Sink: 1.5" (Total Hydraulic load for all 3: (2+2+1.5))

3) As per OBC 7.4.10.6: Maximum Hydraulic Load for 2" Pipe: 24

So I *think* I can use 2" pipe everywhere, properly supported and backfilled of course. Can anyone confirm that my analysis is correct?

Thanks, Ivan
 

John Gayewski

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This is similar to most calcs. If 3"is required it's an anomaly. You'd best ask your local inspection department.
 

Ivan Blackford

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From what I can see from the OBC, the following applies to me:

1) As per OBC 7.1.4.2:
(1) Where gravity drainage to a sanitary drainage system is possible, a floor drain shall be installed in a basement forming part of a dwelling unit.

2) As per OBC 7.4.9.3: Washing Machine pipe size: 2", Floor drain: 2", Sink: 1.5" (Total Hydraulic load for all 3: (2+2+1.5))

3) As per OBC 7.4.10.6: Maximum Hydraulic Load for 2" Pipe: 24

So I *think* I can use 2" pipe everywhere, properly supported and backfilled of course. Can anyone confirm that my analysis is correct?

Thanks, Ivan
Thanks for all your help here, I passed the inspection yesterday with no issues. I ended up not putting a floor drain in the branch I made. I simply moved an existing 3" floor drain to a better location. For the new branch, I used 2" for everything underground, using wyes and 22.5's where necessary. The learned that according to 7.5.1.1 of the OBC:

(3) A trap that serves a floor drain or hub drain need not be protected by a vent pipe separately where,

(a) the sizeof the trap is not less than 3 in.,

(b) the length of the fixture drain is not less than 450 mm,

(c) the fall on the fixture drain does not exceed its size, and


(d) the trapis connected to a horizontal drainage pipe that terminates at its upstream end in a 3 in. stack.

Good information for those looking to do floor drains in Ontario. I can't see a lot of gains in installing a 2" floor drain, unless there are some restrictions on getting a 3" drain connection underground.
 
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