Detached Garage with Studio above - help needed

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kasander

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Hello all, need some professional consultation on my garage project. I am planning on pouring the slab next week, but I need to get the plumbing installed and inspected first. I am planning to have full bath and kitchen upstairs and washer/dryer and sink downstairs, but I was also thinking of installing a 1/2 bath downstairs so I will still have a bathroom if I decide to rent out the studio apartment. So, my question is, will the attached plumbing rough-ins work and have I specified the correct pipe sizes and fittings?

plumbing_3d_2.png


Here is my potential ultimate plumbing plan, I know there may be issues, but I am only concerned with the under slab portion for now... Also, do I need cleanouts anywhere along the main 3" line? The total length from the sweep to the foundation wall is about 20'.

plumbing_3d_3.png
 

kasander

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Nothing? In talking with a plumber I need a vent between the downstairs toilet and the upstairs bath. Still not sure if I can use all those Combo Wyes to go from vertical to horizontal into the main drain line...
 

Cacher_Chick

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Just look and think about how each fixture will be vented prior to its connection to the building drain.

The new toilet needs a vent before the pour.

There must be a cleanout at the base of the main stack above the slab, and every other drain or vent going through the floor.
 

Terry

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The toilet needs to be vented before the enters the main line.
The upstairs lav enters below any plumbing that is on the first floor. The vents from below can tie in at 42" above the next floor.
 

kasander

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I had a plumber help me do the plumbing, then the inspector failed it for running the pipes inside the footer. Apparently you can cross the footer but not run down the length of it. Anyway, here is my redesign, I think this should work.

plumbing_version2.png
 

kasander

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One small tweak to eliminate 2 45s in the toilet drain...

plumbing_version3.png

Now I should be good with a cleanout at the bottom of the stack going to the upstairs bath and one outside the garage where the drain exits the foundation, correct?
 

Terry

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Cleanouts need to be within five feet of a line.
It may be that they will want a cleanout on the lav that wet vents the toilet. I normally put a 3" cleanout there for that reason. Unless it can be routed so that you are within the five foot distance, and keep the change of directions to 135 degrees or less.
 

kasander

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Toilet counts as a cleanout, correct? Not sure I understand where you are saying to put a 3" cleanout. The lav drain/toilet wet vent is only 2".

Also, do I need a cleanout on the 2" vertical pipe going to the upstairs sink?

BTW, thanks for the advice, what a great resource you have built here!
 

Terry

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They don't count the toilet as a cleanout.
At the base of any stack that is more than five feet from a line with a cleanout, you must add one.
The wet vent on the toilet is 2", but if I'm installing a cleanout under the lav, I run 3" there with a cleanout and then run 2" after that.
 

kasander

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Would I be ok installing a 2" cleanout on the sink drain after the p-trap? I don't want to run 3" because that wall is 2x4 studs.
 

kasander

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Hello guys, my garage build is progressing slowly and I am about to put shingles on the roof... Like tomorrow... So I wanted to place my stack vents and flashing before the roofers put the shingles on. I think I know the answer but wanted to confirm. My garage will have a 1BR apartment upstairs. I wanted to minimize the penetrations through the roof.

Plumbing layout is shown below. I have a 3" drain from the upstairs toilet.

Questions:

1. Am I required to run the 3" pipe up through the roof straight with no bends? Or can it jog horizontally and/or be downsized to 2"?
2. Is the configuration pictured below acceptable?
3. I will also have a kitchen sink upstairs, but it will have a separate 2" drain and vent. Does the waste stack on this have to go straight up through the roof, or can it jog horizontally?
4. I will have a slop sink downstairs. Can the vent stack on this sink jog horizontally and join the upstairs sink vent (tie in above the upstairs sink)?
Sorry for my ignorance and thanks for the help!


plumbing_sketch2.png



Upstairs bath configuration:
upstairs_bath_dwv.png
 

Terry

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The tub gets vented before it enters the line with the toilet.
The revent on the lav should be 6" above the flood level, or 42" normally.
 

Reach4

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Maybe something more like this..
 

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hj

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I would have tied the upstairs toilet into the downstairs toilet's line, instead of going "around the world", and put a cleanout on the riser above the floor.
 

kasander

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hj, I had to route around the footers for a load bearing wall. See my very first post for my original layout which would have been close to what you are describing.

Reach4, thanks for the suggestion.

My main question is how many and where am I required to vent the stacks out through the roof? (Which ones can run horizontally and meet other vents?)
 

kasander

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From everything I am reading, it looks like I can run horizontal sections in any of the dry vent sections in the attic space. I will plan to cut one hole for a 3" vent above the waste stack (on the far right side) and one hole for a 2" vent above the drain for downstairs sink option 2. Then I can run the vent from the upstairs sink horizontal and tee into the 2" vent in the attic space. Sound good?
 

kasander

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Yes hj, but with the drains so close to the footers and the footers being so wide, I didn't want to have anything close to going through them so I just angled away from them. Can you let me know if my vent plan is ok? Sitting in the garage with a drill and holesaw right now...
 

kasander

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Ok, drilled two holes through the roof. If I end up needing to add more later, I'll just have to cut through shingles.
 
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