MiamiCuse wrote:
Recent video inspection revealed that my 40 year old cast iron pipe
under the concrete slab is deteriated to the point of needing total
replacement. Some spots the bottom has reduced to nothing, some spots
the corrosion build up looks like the inside of a cave...two
independent video inspections recommend total line replacement.

I have not yet done the finished flooring in the house, so I guess
it's good news I found out now.

In order to replace the entire underground line, I can find a way to
determine exactly where it is (no, no records in the city I checked
already), and cut up the slab and hope for the best. Or I can just
ignore where the existing line is and just design a new route.

It seems designing a new route but tying in existing bathroom group
has the advantage of not having to pinpoint exact locations of the
line but only specific locations where the existing bath groups tie
in. And since I am doing remodeling, 3 of the 4 baths I know where
they tie in and I have not backfill with concrete yet.

Doing a new line has the advantage of avoiding cutting a trench across
existing walls, I can possibly cut a line along a hallway in a
straight shot, but run the risk of running into other pipes below
grade that may be in the way (pool pump lines, supply lines, deck
drain lines, roof drain lines).

What is the ramification to the structure of the slab is it's a
90'x90' slab and I cut a 90' lone trench across it?

Is there any sense in not making a single 90' cut, but say 8 10' cuts
with several 2' sections uncut and I try to bridge under it will that
"hurt" the structure any less?

I am laying in new 4" PVC pipe so the trench would be around 6" wide
only except where I am doing tie ins.

Thanks in advance,


Do you have fire insurance?