floor drain vent problem in pole barn

[timf]

Lots of great information on this site!

I’m roughing in under slab drains and trying to find a way to properly vent a floor drain. The problem is that the catch basin for the drain is in the middle of an open floor with the closest wall for a vent 20 feet away. How can this be vented?

I’d like to use 2” pipe if possible, but could use up to 4” which connects the building to a septic tank. The connection will also serve a toilet, sink, and shower.

Thank you!

[hj]

If you are even thinking about connecting a toilet to it, then it HAS to be either 3" or 4". We cannot even begin to tell you how to vent it without seeing the structure.

[jimbo]

Remember that a floor drain needs a trap primer.

[timf]

Thanks for the help.

Here is a sketch of the building



I have 4” ABS to the building. After that I’m planning to reduce to 3” and have a 3” – 2” reducing wye to the shower and a 3” wye to the toilet and floor drain. I think I’m clear on how to vent the shower, sink, and toilet. There will be a 3” vent stack near the toilet for venting those.

In the middle of the building is where I want to put the floor drain. That’s what I don’t know what options are available for venting.

Does that help?

Thank you,

Tim

[timf]

I'll look into that. Is the primer connected directly to the trap and how is this connection made?

thanks,

Tim

Remember that a floor drain needs a trap primer.

[jimbo]

Yes, a primer will somehow dribble a little bit of water into the drain ABOVE the trap. It can be an active device, tapped of a water supply line, or it can be a passive tap, off a flushometer. That option would not be good for a restroom that gets little use. The primer only gets water each time the toilet is flushed.

[timf]

I'll see what's available here and add a primer.

thank you

Yes, a primer will somehow dribble a little bit of water into the drain ABOVE the trap. It can be an active device, tapped of a water supply line, or it can be a passive tap, off a flushometer. That option would not be good for a restroom that gets little use. The primer only gets water each time the toilet is flushed.

[ballvalve]

Use a trough with a grate so you can hose into it full length and use it as a screed. No traps.

[Terry]

You have to have a trap inside a structure or you will have an open pipeway from your septic.

I would go with either a 3" or 4" line to the trap. From the trap you can put a bushing in on the vertical and use 2" there.
By oversizing the waste line, you allow air over the line to naturally vent the waste line and prevent siphoning.
The oversized line acts as both waste and vent.

A trap primer keeps the trap full so that sewer smells don't ruin what could be a pleasant experience.

[ballvalve]

http://www.zurn.com/operations/flothru/pages/home.asp

This is what I had in mind. You can slope to one end or the center and of course place a trap there. I cast my own with a sloped bottom, but its a bit of a job.

You could slope it outside and likely just put it into a dry well unless someone is using the floor as a toilet.
why put it into the septic?

Screeding that slab to one center drain won't be an easy job to do right.

As to a trap primer, they are only required in a commercial food operation in CA, such as a winery. Otherwise, thank god, they assume you use the drain, or have brains enough to fill it when it stinks.

The best trap "primer" is some old fry oil. No evaporation to speak of then. Thats what a good caveman would do [1942 popular mechanics]

[timf]

That helps and seems it would work fine. A couple things I'm not understanding though:

1) Some vent tables I saw listed 10' as the maximum distance for a horizontal 4" pipe that had waste and also acted as a vent. Am I misunderstanding that and is it OK to run a 3 or 4 inch pipe like you descibe 15 feet before it has a vertical vent?

2) The local inspector said I need an oil / water sererator. Is this normally the case? I'm not planning to dump oil down the drain, but want to be able to hose the floor off into the drain.

thanks!

Tim

You have to have a trap inside a structure or you will have an open pipeway from your septic.

I would go with either a 3" or 4" line to the trap. From the trap you can put a bushing in on the vertical and use 2" there.
By oversizing the waste line, you allow air over the line to naturally vent the waste line and prevent siphoning.
The oversized line acts as both waste and vent.

A trap primer keeps the trap full so that sewer smells don't ruin what could be a pleasant experience.

[timf]

Thanks for the link.

I just want to be able to wash dirt that gets tracked in off the floor into the drain. The local plumbing inspector said it needs to go into the septic and not onto the ground like the gutters.

I'm planning to use for vehicle storage, but the requirements seem like they are considering it more like an automotive shop and trying to protect from someone dumping oil down the drain, or onto the ground.

Tim

http://www.zurn.com/operations/flothru/pages/home.asp

This is what I had in mind. You can slope to one end or the center and of course place a trap there. I cast my own with a sloped bottom, but its a bit of a job.

You could slope it outside and likely just put it into a dry well unless someone is using the floor as a toilet.
why put it into the septic?

Screeding that slab to one center drain won't be an easy job to do right.

[ballvalve]

Isnt it interesting that if he just sloped the slab to the big doors, no drain, seperator or primer would be required. These are the fine details of the code that makes smart people cheat the absurd laws.

If this is a quickie lube shop, inspector god has a point. Otherwise they live to make a lot of needless trouble. Change your plan.

And title it "hay storage barn". They see car storage, and floor drain, and they move to commercial code.

I just did a plan change from a fold down attic stair into a real attic staircase, like every damn house built before 1970 had. Building wanted 3,000$ because now it was "too easy" to convert to living space. Got them down to 300$ by not being a poodle, mentioning blocking the aged and disabled from the attic, and agreeing to send them a file letter 'promising' not to convert without a permit. Good joke all around.

[timf]

Good story!

I think i need to go talk with the inspector again.

Trying to do it right and don't plan to dump oil on the ground or in my septic! But, yes, it seems to be OK to have a door I can wash dirt out of, but as soon as it's a floor drain, it's different.

thanks,

Tim

Isnt it interesting that if he just sloped the slab to the big doors, no drain, seperator or primer would be required. These are the fine details of the code that makes smart people cheat the absurd laws.

If this is a quickie lube shop, inspector god has a point. Otherwise they live to make a lot of needless trouble. Change your plan.

And title it "hay storage barn". They see car storage, and floor drain, and they move to commercial code.

I just did a plan change from a fold down attic stair into a real attic staircase, like every damn house built before 1970 had. Building wanted 3,000$ because now it was "too easy" to convert to living space. Got them down to 300$ by not being a poodle, mentioning blocking the aged and disabled from the attic, and agreeing to send them a file letter 'promising' not to convert without a permit. Good joke all around.

[Tom Sawyer]

Most localities won't allow a floor drain to be installed in a garage because anything that leaks from the vehicle can end up in the sewer.