Will this basement bathroom pass plumbing inspection?

[Tommy Fox]

I have been reading and learning a lot from this forum.

Finally, it is time for me to apply what I think I have learned.

I am building an addition (with full basement) to my house.

This new addition would have a new sewer pipe under the slab. This pipe would eventually meet up with the existing main pipe near the curb.

Here's the overall layout of the basement bathroom:

And here's my plumbing design:

Obviously, the red lines are the vent lines. The two vertical vent would eventually meet at the ceiling near the vertical stack. I don't have a vent for the toilet as it would be vented thru the main stack.

I didn't draw the trap arms for the shower or the vanity.

I may have to insert extra "bends" to make all the pipe aligns, but those should not affect the basic design.

I was thinking this is a relatively straightforward design.
I would like to know if it is correct, and will pass the necessary inspection.

Location is NJ.

Thanks in advance for all your help.

 

[Cacher_Chick]

Fail.

All vents must be vertical until they are at least 6" above the flood rim of the highest fixture served by the vent, or 42", whichever is higher.

It is never acceptable to route a vent horizontally under the floor because it will fill with waste the first time there is a backup.

A single bath only requires a 3" line for the water closet.

I'm sure your plumbing code is available online. It is worth studying before you jump into such an endeavor.

 

[Sponsor]

 

[Tommy Fox]

Thanks for the correction.

Did read about the no horizontal venting rule before, but neglected to apply it here.

Here's the updated design, the shower vent now goes up on the front wall

I understand the toilet need not have a 4" waste line. But is it really better to use a 3" line?

There is no separate vent for the toilet. It's vented thru the main stack.

Just want to note that there is another bathroom on the first floor right on top of this.
Fixtures in that bathroom would drain into the main stack.

With that, it is still ok to vent the basement toilet thru the main stack, correct?

Thanks

 

[Cacher_Chick]

The "main stack" you refer to is the drain for the fixtures above. It cannot be used as a vent.

What would be permitted is to wye in the vanity drain to the water closet drain PRIOR to its connection to the building drain. This would allow the water closet to vent through the vanity vent, and the vanity would serve to wash the vent clear of solid waste.

I think you will have problems maintaining the required 2% grade on the horizontal wet vent, unless the building drain is deep enough below the floor to run the vanity drain line over the top of it. The connection of the lavatory to the water closet drain must be made with a wye on it's side.

 

[Tommy Fox]

Very useful feedback. I greatly appreciate it.
I am learning rapidly.

This is a addition with a new basement.
None of the lines have been laid.
So I will run the main building drain further back, hope this will allow the toilet to drain into it from the other side.
This should make the wet venting into the vanity drain much easier.

I am keeping the toilet waste line at 4". This way I can use an internal toilet flange.

Here's the revised design

Hope this will finally pass now.

 

[Cacher_Chick]

Now you have it. You can use 4" for the WC, but I would use 3" with a 4x3 closet bend. The smaller pipe is beneficial in that it will be fully scoured by the single WC. 4" is for multiple baths or a building drain.

 

[Tommy Fox]

@cacher_chick, can't thank you enough for your help.
Hope my inspector are as nice as you are.

I already mentioned I have a first floor bathroom right on top of this.

This exercise has been great for me.
I figure I may as well show the first floor bathroom design to get some feedback.

Here it is:

And the plumbing design

Again, vent pipes are red. I have not included the trap arms.
You can see the vertical stack that extend to the basement.

The bathtub is wet vented via the vanity.
And as advised, I am now using 3" pipe and 4"x3" closet bend to server the toilet.

To complete, here's how I intend to tie all the vent pipes together at the ceiling of the 1st floor, then run a single 3" vent pipe thru the 2nd floor and then to roof

With what I learned from the basement bathroom, hope I'm making fewer mistakes here.

 

[Reach4]

If you are in a snow area, you may be required to increase the diameter for the roof penetration. I think that is to account for potential narrowing due to dripping moisture freezing on the walls of the pipe.

 

[Cacher_Chick]

Your drawing does not specify, but the vent connections from the basement must be at least 42" above the 1st floor.

There is no concern of frost closure on a 3" vent stack.

 

[hj]

quote;
There is no concern of frost closure on a 3" vent stack.


Maybe not where you are, but we ALWAYS had to use at least a 4" pipe through the roof, on anything 3" and smaller. Larger pipes had to be increased at least ONE INCH before they exited through the roof.

 

[Cacher_Chick]

You are right HJ in that everyone should refer to their applicable plumbing code.