Toilet waste pipe from attic, added to original stack, advice needed

[Jim112]

Would love to get more info here before I undertake costly repairs. Posted a similar qs recently but I made a mess of it, so here's another attempt

Relatives added a toilet in the attic a few years ago, have had problems recently with blockages and odors

- I've never seen a waste pipe added here, is this something that anyone has seen / done before? I would be v cautious adding a new toilet to existing setup, particularly a horizontal section since it has to change direction, but i know little about plumbing
- It seems to cause problems with the vent so I don't know what they were thinking
- Whats the best fix? Altering where the pipe joins the original stack or a new stack, closer to the attic toilet?

Any info / opinions welcome

What you see in image 1:

- The large black pipe coming from the eaves joining the horizontal part of the stack is a waste pipe from the attic toilet (this section of pipe is where the most recent blockage happened). This was added in a few years ago.
- The white pipe beside that is shower / sink water from attic toilet.
- As we go down we have a white pipe (1st floor sink), large black pipe (1st floor toilet) and another white pipe, from the first-floor shower.

 

[Breplum]

Plumbing code prohibits doing what was done because of a long list of reasons.
Amongst them, #1: That 'tee' at the eaves is NOT a drainage fitting, it is a tee in a position which is prohibited (for a good reason). Prohibited because it will not allow solids to flow freely.
Whoever did that work were COMPLETE IDIOTS. Sorry, but that is just the hard truth. The side tap where the white pipe suffers the same problem, ie, drainage fitting it is NOT.
Hire a real plumber or you will never stop having problems. File complaint against whoever charged for such nonsense so that they will be barred from committing guaranteed failures.

 

[Sponsor]

 

[Jim112]

Thanks @breplum - for the info, I thought the work was done by a complete idiot but wasn’t sure

I didn’t hire them but I know one of the other crew involved and wouldn’t be surprised if someone unqualified done this considering the info you gave. Following up on it but not hopeful of getting any answers

Will get a pro in