Running basin and bath waste into unused stack.

[williamglossop]

The current waste stack on my house won't be needed much longer. I'm having a side extension that has a new open vented stack on the gable wall. The toilet waste will be re-routed to the new gable wall and into the new stack. My basin and bath waste currently run into the same existing stack.

I need to re route my basin and bath waste as they will be inside a new bedroom and they currently run into a stack that is to be removed.

Is it allowable to cap off the existing soil stack near to the floor and run the basin and bath waste into it? Pictures will help explain what I mean....

This is the current (temporary) set up. The main pipe is cast iron the toilet and both wastes run into it. The toilet waste is being routed as shown below....

It will be run between the 1st floor joists to the gable end and into a new stack.

Could I cut the cast iron pipe near the floor and replace it with a short length of plastic pipe and fit one of these....

Originally, there was a second stack next to this cast iron one that was asbestos and had a hopper on top of it through the garage roof. The wastes ran into this hopper. The asbestos pipe ran into the same underground pipe as the cast iron pipe, but I assume they were separated by some kind of trap to keep the sewer smells out of the garage....

Is something like this acceptable...... or does the pipe have to be capped off completely if its not got any air admittance?

 

[williamglossop]

My other idea would be to fit an air admittance valve on top of this pipe (cut down to a height below new garage ceiling and then come into the stack with strap on bosses. I know AAV have to be higher than the basin, but would that still apply if the stack is fully visible? Ie NOT boxed in and in a garage.

 

[denso13]

I know AAV have to be higher than the basin

They don't actually, depending on which one you use.

 

[williamglossop]

So.....I could replace that cast-iron pipe with plastic and connect both wastes into it and fit an AAV at least 200 mm above the highest one?

I always assumed aav had to go above the highest point on the run, in this case the basin over flow..... ill be happy if I'm wrong

 

[denso13]

I could replace that cast-iron pipe with plastic and connect both wastes into it and fit an AAV at least 200 mm above the highest one?

Yes, that's fine.

 

[williamglossop]

Thats great. Thank you.