Pitched roof replacement

[richard.malec]

I have a pitched roof on the kitchen at the rear of my property, above this is the bathroom and the soil pipe exits through the wall and then through the pitched roof then connects to the main vertical pipe. my problem is the roof leaks and needs replacing, and I have been informed that the soil pipe will have to be re routed as building regs wont allow the pipe to go through the roof???
is this the case??

some other details are that the house is 2 up 2 down and the rear bedroom was made smaller to have an upstairs bathroom a good 10yrs before we purchased the property 5 yrs ago (guess work on those time scales), I really appreciate any help that can be offered, I'm not a builder and don't know what to do, I don't want to have unnecessary cost.

Kind regards

Rich