cast iron under slab

[TPL]

I need to replace all of 1970's cast iron under my basement slab. If I were to redirect the 4 inch main line straight out from the wet wall through the stem wall, I could cut out a considerable amount of trenching of the slab that the existing route of the old line takes. Then trench along the outside of the house to the sewer. Is this a good idea? And what is the process of getting through the stem wall without compromising the structural integrity of the stem wall? Thanks

 

[Breplum]

re-routing is fine as long as you have a cleanout for any run over 5' and any change of direction cumulatively over 135 degrees.
Core drilling is the smallest hole, usually sub'd out to a specialty core driller.
BTW, most residences only need 3" drain inside the building with less that 4 toilets. Outside, 4" is fine.

 

[Sponsor]

 

[Reach4]

Is there ever a basement sewer backup in your area? If so, consider switching to "overhead sewers".

Basement sewage flows to a vented ejector tank. That contains a grinder pump if a toilet feeds into there, and can be an ejector pump if it is just kitchen and laundry etc drainage.

Drainage above the basement gets feed by gravity.

If you don't go with overhead sewers, there should be a backwater valve in line with basement-generated waste. The much-better kind is the normally open backwater valve. Dangling flappers nearly always leak with time.