Double San-T

Slab on grade, one bath, back to back with Kit.
My sketch shows the bath tub, wc and a floor drain for the boiler/HW, with a 3" branch in the plumbing wall to pick up the two sinks and laundry tub. My inspector says the double San T for the wc and floor drain is wrong. We use the 06 UPC and in 706.2 it says the double san T is ok if I am reading it right. My inlets are 3" and the 4" barrel would be two pipe sizes larger, 3"-3.5" then 4". What do you think? The inspector wants me to dig up the slab and replace the san t with a double fixture fitting or fill in the floor drain with concrete. The pipe above the slab has not been done yet, but this is what I thought it would be. Do I need vents in the 3" branch? All trap arms are well within the critical distance. The inspector wants each of the fixtures in the 3" branch to drain separately into the 4" stack, not to use a branch. He also wants me to use a laundry tub (2 fixture units) for the washer drain hose instead of a stand pipe which is 3 fixture units. Thanks for the help.

You can't wet vent the kitchen sink and the washer over the toilet.
Those need to come in below the toilet. And they need to have their own vents, which can tie into the vent stack above the flood level of the highest fixture.

You need to install a double fixture fitting, if you intend to use a cross fitting. Just for your own knowledge, when you flush a toilet with a sancross, the water skips over to the other side. That's why the inspector wants you to cap that side off.

Heck, with the new toilets I don't like using any kind of cross now. I prefer to bring them in so that the waste points its way down the stack, not allowing skip over.

Sanitary crosses have not be "code approved" for decades, although from what some have posted here their inspectors still allow them. Just plugging the floor drain will NOT remove the objection to it. And if he is giving you a pass on your venting for the sink, lavatory, and laundry you are already money ahead. I would have used a side inlet sanitary tee for the toilet connection with the floor drain into the side of it.

In addition, the floor drain would have to have an inlet into it above the trap for a trap primer valve's discharge.

hj said:

Sanitary crosses have not be "code approved" for decades, although from what some have posted here their inspectors still allow them. Just plugging the floor drain will NOT remove the objection to it. And if he is giving you a pass on your venting for the sink, lavatory, and laundry you are already money ahead. I would have used a side inlet sanitary tee for the toilet connection with the floor drain into the side of it.

Click to expand...

Are you talking about laying a san tee on its side for the floor drain,or a closet 90 with a side inlet?

No, he is talking about a side inlet sanitary tee...

When you refer to "two pipe sizes" there has NEVER been a 3 1/2" drain size. In fact it is an "artificial size" because you cannot buy a 3 1/2" anything, except an occassional 3 1/2" x 2", or other size, galvanized bushing.

hj said:

When you refer to "two pipe sizes" there has NEVER been a 3 1/2" drain size. In fact it is an "artificial size" because you cannot buy a 3 1/2" anything, except an occassional 3 1/2" x 2", or other size, galvanized bushing.

Click to expand...

Well....you can buy a 3.5" brass cleanout plug. While its not the drain size it is the cleanout plug size for future reference.

Hackney adds confusion for no reason, again.