# Mop sink



## redbeardplumber

Have never installed a mop sink. Bidding a small commercial job.

What do I need to know? I assume it's a 2" drain.

The owners actually want to just RI the p-trap in floor for now and install later. Should we box out drain? Problems?


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## john433

Mop sink is going to be 3or 4 inch if it is fiberglass box out drain for strainer


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## john433

Never seen one with a 2" drain but up here by code has to be 3" might want to look at the spec


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## plbgbiz

You can get it with a 2" or 3" donut gasket depending on how you want to run the drains. Depending on how the walls are being finished will determine whether or not it gets set on the topout or finish. That will also change where you rough in the drain. I do mine on the topout roughed in from the studs.

Here are some quotes from a previous thread that might help as well.



Killertoiletspider said:


> I always leave four inches above what they say finish floor is going to be and trim it off later, so that when the finish floor is actually an inch taller than it is supposed to be your covered. I actually do have an internal cutter for cast iron.





No-hub said:


> Block out and leave No-hub coupling 6 inches below. Saw cut jobs I cut so I can install it on rough-in.





ditchdigger said:


> Block out with styrofoam box when you get ready to set it mark the pipe as needed cut it pour concrete back set the mop sink .





fightnews said:


> No 1/2 inch above finished floor is perfect and much more efficient. Plus I use 6" smoke pipe to block out. Actual blocks are old school.


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## Pipe layer

I would have the owner supply a spec for you and still box it out.


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## redbeardplumber

Thank you guys!

Biz what is the name of that thread? It is not coming up on a search. Those comments help huge thanks. All these years, no mop sinks....


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## plbgbiz

redbeardplumber said:


> Thank you guys!
> 
> Biz what is the name of that thread? It is not coming up on a search. Those comments help huge thanks. All these years, no mop sinks....


http://www.plumbingzone.com/f8/fiat-mop-sinks-20157/


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## redbeardplumber

If these mop sinks require large drains, do you guys feed the faucet 3/4"?


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## Pipe layer

I always use 3/4 supplies for mop sinks and don't forget to install backing for mop hangers and hose brackets as well. And be precise with your waterline rough-in because the faucets don't give you a lot of room for error.


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## Rando

redbeardplumber said:


> If these mop sinks require large drains, do you guys feed the faucet 3/4"?


I think the larger drain is for dumping a mop bucket. Although a lot of times they will call for 3/4 supplies to the mop sink faucet on the prints. 
I get to set two Terrazzo mop sinks on my project today.....yay.


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## TC27

also remember backing for the faucet brace..


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## ILPlumber

TC27 said:


> also remember backing for the faucet brace..


True dat. They will hang a 5 gallon bucket on it....

I use 6" pvc scraps to block out of the drain. I always have cut offs laying around from other jobs.


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## bct p&h

plbgbiz said:


> You can get it with a 2" or 3" donut gasket depending on how you want to run the drains. Depending on how the walls are being finished will determine whether or not it gets set on the topout or finish. That will also change where you rough in the drain. I do mine on the topout roughed in from the studs.
> 
> Here are some quotes from a previous thread that might help as well.


I've never liked the donuts. Every mop sink I put in I pack and pour. PVC, cast, fiberglass or plastic base all get lead and oakum.


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## Bayside500

bct p&h said:


> I've never liked the donuts. Every mop sink I put in I pack and pour. PVC, cast, fiberglass or plastic base all get lead and oakum.


that may void the warrenty on some mop sinks if they supply a rubber gasket ya think ?


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## Plumbus

Just finished trimming out the faucet on an MSB2424. There was backing for the brace but it ended up half way on and half way off the top of the tile splash. Not our fault, because the plan didn't have an elevation showing the height of the tile. Of course, my plumber could have given the GC a copy of his cut sheet on the faucet. I'll bet the tile height in the janitor's closet could have been lowered a couple of inches without any repercussions. Fortunately, the faucet stubs are solidly secured.


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## bct p&h

Bayside500 said:


> that may void the warrenty on some mop sinks if they supply a rubber gasket ya think ?


I'd rather eat a $200 mop sink than a ceiling and whatever else is underneath it. I've probably done a couple hundred mop sinks with lead and oakum and have had no problems with any of them. I also pack and pour those shower bases with the molded drains. I've yanked out a handful of those rubber donuts because they leaked. You just have to be easy with them so you don't crack them.


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## Rcplumber

Load drain up with silicone then install rubber donut making tight seal around drain and rough it in at 12 1/2 x 12 1/2 that will work for a 24x24 mop sink if your r going off of stud walls if Sheetrock just take 1/2 inch from measurements


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## MDPlumber1977

bct p&h said:


> I'd rather eat a $200 mop sink than a ceiling and whatever else is underneath it. I've probably done a couple hundred mop sinks with lead and oakum and have had no problems with any of them. I also pack and pour those shower bases with the molded drains. I've yanked out a handful of those rubber donuts because they leaked. You just have to be easy with them so you don't crack them.



Pack it, Pour it, and cut the stub up to height with a butter knife (if its PVC). Lead... Almost as useful as Duct tape


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## wyrickmech

I never use the seal that comes with the sink unless it is slab on grade. The old time tested method works fine just remember not to pack the lead until it has cooled and pour the lead a little cool. Just with a slight blue color on the lead after you skim the impurity s off the surface


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