3 1/2" cast iron

[davebigpipes]

At my own house I have created a downstairs wc the soil stack is right outside where the wc is but its 3 and half inch cast iron, I will replace the whole thing when we redo the bathroom upstairs but for now I want to cut the stack a meter up and use new 110mm PVC into ground and a tee to New wc. Is it ok regs wise to join new bottom with one of those rubber connectors for waste pipe that have jubilee clips on?

 

[kirkgas]

3.5" CI is only supposed to be used for one stack, but when i converted my loft i had the choice of digging up the concrete to renew the last 800mm to 110mm plastic then a 110mm branch reducing down to the 3.5"CI, but guess what i done, yes thats right i fitted a timesaver bolted joint onto the CI at ground level then a bit of 110mm platic and branch the back down to the 3.5" CI, and it works perfectly, even with the chance of both bathrooms being flushed 10 seconds apart and the water from both hitting the 3.5" at the same time isnt going to effect anything and when either are used on their own it is the same as the single stack, but at the end of the day digging up and renewing is right, what i did works fine haha (do as i say not as i do)