Every poster here should tell you the same thing. STOP, DON'T EVEN ATTEMPT IT. What are you thinking?
Gear here is the Deal ... The 4" will be snap Cut No Problem ... Already Did the Cuts on the Small stuff ...
Will Probably Have to Cut the San T at the base of The Stack With an angle Grinder Then reline the 4" stack with 3" (Nothing Enters the stack)
As far as Pricing goes Will Probably Go Time and Materials Then Throw in about $250.00 For All the Sand packed in every Crevice ... Ears Hair Face Mouth Etc ... + general Aggravation ... Just Wanted to get a Consensus of the Group ...
I wish you the best of luck and be safe. Just throwing out some crazy idea, why not just cut the slab.
Buy cheap, buy twice.
Pronounced A-Bear Drain Care
I know, it doesn't make sense.
Tile Bathroom People Living in House (Rental) only one Bath room ...
What ever you charge will be too little. I would not do the extra $250 but would figure what busting the slab and doing the repair the safe way would have cost then decide what your fee for doing it this way will be.
Why the hell would you do something like that? Occupational health and safety would be all over this and if you do have an accident under there you will have no coverage assuming you get out alive.
Why would you not just tell them that the slab has to be opened up and either sawcut it or rent a jackhammer and expose it? If it is a rental and there is only 1 bathroom then it is up to the landlord to either put the tenants up in a hotel or make some other alternate arrangements.
Tunneling is illegal under the UPC but is allowed under the IPC. However, the IPC says something to the effect it must be safely supported. I don't see any support and would not have done the job that way.
On another note there is no way possible to properly backfill that job. I represented a concrete pumper who was hired by a plumber who did that exact same job. When the plumber had him pump slurry into the tunnel for backfill it caused bellies in the pipe and lifted a 40' section of the slab. All my guy did was supply the equipment but the plumbers insurance went BK and my guy was stuck with the bill.
"Somewhere a Village is Missing Twelve Idiots!" - Casey Anthony
I never lost a cent on the jobs I didn't get!