cut into vent stack

[mistermann]

Sorry, I did look to see if this was covered elsewhere but couldnt find it with my specifics

I want to put a toilet in my new loft conversion. The nearest down pipe is a cast iron stack (4 inch) which comes out of the ground with nothing connected to it. It runs into the same drain (i lifted the manhole and counted the branches)as an existing plastic stack goes into which is my original wc. I assume the cast pipe is some kind of drain vent pipe then(?). It has no gully at the bottom.

So, my 2 questions, if anyone can help, are,
1)can I put a timesaver into the cast stack and run a new toilet into it?
2)If I can, do I need to make the stack taller, extending it above the bedroom window?
Thanks

[peter the plumber]

Well if it’s in the loft, you could just cut the soil stack at the right place and put a 110-flexi coupling and then use plastic 110 waste pipe for the toilet in the normal way.

Then add an air admitter’s valve on pipe.

[mistermann]

Thanks Pete, I see what you mean. However, I dont think I made myself clear enough on my first post.

The Stack I am assuming is a drain vent is a hundred times more accessable than the plastic stack.

So, is cutting into the cast vent bad practice or contraviening any bylaws?

Thanks again

[peter the plumber]

I did see this last nite but it was late.

Ok if it’s a secondary ventilated system, the vent pipe is not 4 inches/ 110mm.

They’re normally smaller and about 2-3 inch pipes, only time they would be bigger is when they have use 6-inch/150mm soil stack.

If it is a vent stack, you can’t add anything too it.

There are regs for this; the stack is not design to handle waste.

If it’s still in uses, leave it lone.

The system is generally adopted in situations where it is not possible to have close grouping of sanitary appliances and long branch discharge pipes can be expected.