to answer your ? ? ?'s about the multi-story building, let me say what happaned on one job i did a few years ago,
got a call from supv. about job 1 tech. had walked off already becausr of h/o "attude"
main line blockadge in single story house
i knew it was going too be bad job, but decided
to give my best anyway,
i got to the job, back up plumber was to meet me was hung up on other job, ie; this was a middle of night call ! !
so i decided to take care of the job my self, could not run though roof vent by myself
but hey i had a 40,000 psi. trailer jetter on the back of my truck,
so i pulled out enough hose to reach back to side of house up ladder and ran down the main vent stack out as far as i could push it
started up jetter and cranked it up to about
2,000 psi. shut down, check inside still blocked up went back and cranked up too 4,000 psi. held for a count of 15 or 20,
went back inside the house,
the line was now opened, but the BATHROOM
WAS A NASTY SHADE OF BROWN ALL OVER ! !
it came out of the toilet, bathtub, & lav sink,
so you don't want to imang what that would do
to a multi-story building ! !
O. K. RICK YOU ALL GET A BIG LAUGH AT ME ! !
P.S. this homeowner was a city building inspector in a town my co. did work in,