Two toilets on one horizontal waste branch

[VirginPlumber]

Hi,

Im quoting for a customer that currently has a bathroom (no w.c.) with a small sperate room (with w.c.) nextdoor. These rooms are adjoining and the customer wishes to add another toilet in the bathroom that currently has no W.C.

This would basically mean extending the current branch that holds one w.c. and extending it nextdoor to accept the second.

Assuming I can get an adequate fall on this branch, I have 3 questions...

1) is there any buliding code prohibiting this in a domestic situation (siphonage of trap?)
2) Can anyone reccomend a suitable fitting for the T that lies behind the W.C. to prevent any siphonage
3) Does the addition of the second toilet require an alteration in the ventilation?

I know this topic has been covered before...but no clear answer seems to have been reached...

Many thanks in advance,

The Virgin Plumber

 

[muggles]

I'm intrigued as to how you're proposing to achieve this "adequate fall" with this configuration. What exactly do you believe an "adequate fall" to be, and how big a plinth do you want to build for the upstream toilet? What kind of stack are you proposing to connect into?

EDIT: I have just spotted a flaw in my questions, in that I've assumed you're adding the second toilet upstream of the first, which may not be the case. Is this correct or have I jumped to a conclusion that is in fact wrong?

 

[John506]

Connect both toilets to the stack seperately, each having an adequate fall?

There are no building regs to what gradient it must be, just needs to be enough for the nasty stuff to get away but as you say not to pull the trap, just put them slightly on the pi$$ if you can so it will drain away without running full bore and it will be fine.

 

[mattylad]

We have 2 into one horizontal pipe in the bogs at work, the furthest from the end is always blocking up.

Or maybe we are just big S......ers.

 

[VirginPlumber]

You are correct the next toilet will be "upstream". about 5 feet away....this i guess means it only needs to be a couple of inches higher, which as the floor is being plied and tiled i hope may just about be achieved. Particularly if i can lower the branch/stack junction by a few inches (going to mean replacing a section of stack.

My real concern is the conflict with building regs and the chance of sucking out the first toilets trap....

any thoughts????

 

[muggles]

The fall should be 2.5º, or 44mm per metre. Five feet is roughly 1.5m, so you need a fall of 66mm.

I would be inclined to use a tee on both toilets, with the upstream one having a Durgo valve connected into the higher end of the tee, this will ensure you don't suck the trap

 

[VirginPlumber]

thanks for that....why do you suggest a T for both wastes...surely the upstream one will work with just a bend?

Can you tell me what a "durgo" is? Ive not heard of them,

many thanks for your input

 

[jay1]

durgo is an aav (air admitance valve)

 

[doitall]

http://www.polypipe.com/polypipe/controller?action=CBS-TerrainDrainage

Then go to downloads-Installation guide-soil and waste fittings.

 

[GPlumb]

Like this

View media item 5706

 

[muggles]

Like this

View media item 5706

Yup that's pretty much what I had in mind, although with the fall going towards the stack rather than away from it

 

[GPlumb]

Like this then: View media item 5800

 

[muggles]

Like this then: View media item 5800