Draft Dodger
LE

I had a leak where a toilet waste pipe joins to a wall and as with much of the rest of the house this appears to be the result of some poor bodging. The original 110mm waste pipe is lead and stops flush to the wall however at some point the lead has been buckled around the inside (my guess is someone tried to force in another section of pipe as they went to plumb in the toilet, anyway...because this is buckled (but still sound) I cant fit in a standard toilet waste pipe connector. Neither could the bloke who tried previously but this is something he tried to rectify by slapping silicone everywhere but obviously without success.
As I dont want to have to remove the existing lead pipe I'm thinking about running a flexible pipe (90 or 100mm) through the wall so that it reaches the drain and then adapting/mating it to a wall plate/connection with an exterior 110mm connector. my questions;
1. Can I get away with this without the toilet blocking/backing up every time it gets flushed?
2. Is this a stupid idea for reasons I havent even thought of?
As I dont want to have to remove the existing lead pipe I'm thinking about running a flexible pipe (90 or 100mm) through the wall so that it reaches the drain and then adapting/mating it to a wall plate/connection with an exterior 110mm connector. my questions;
1. Can I get away with this without the toilet blocking/backing up every time it gets flushed?
2. Is this a stupid idea for reasons I havent even thought of?