Hopefully I can explain this clearly....
House on single level with crawl space below. But, newest addition with 1.5 baths is about 18" higher, as is it's crawl space.
Older 2/3's of the house has 4" main waste line at crawl space grade and sloped correctly. The addition when done was all higher and they basically and oddly ran down their 3" main at a 45 degree slope to join the existing 4". Seems odd to me.
As I'm needing to correct some things in new section, I can change this. My thought is that it would be better to 1/4 turn vertical down, then 1/4 turn back to horizontal to join back to existing line.
Is this preferred, or the odd slope to where the two intersect? I guess third option would be to excavate way down in new area crawl, to match slope of existing but seems like a lot of work and would effectively bury the plumbing.
I think the way to imagine this might be a vertical stack from a second floor comes down 15 feet away from horizontal main waste line in crawl space. Would you run it at an angle until it intersects, or 1/4 turn and maintain slope until directly over main line and drop in top via a combo.