Are there any issues regarding tunneling under a slab? I live in a
remote area, dry, with mostly clay soil (very stable).

Difficult and expensive to get "pros" to work out here, and for personal
reasons I won't go into I need to save my pennies.

I'm kind of jealous of people with raised foundations who have such
great access to their plumbing. I posted awhile ago about my plumbing
woes, and sure enough, one of my drain lines has been broken under the
slab and is full of mud and roots.

The break is about 22" under the lip. Measured at the perimeter, my slab
is 12" thick...it thins to about 4" moving under the slab. There is a 40
ga. hot water heater above the area I want to excavate, but most of that
load is spread outside the proposed tunneling area.

I'd really like to dig a tunnel under the slab, making a crawlspace for
accessing the plumbing. All of the house plumbing joins up in this one
area.

My idea is to excavate it, pour a footing around the perimeter, brick it
in, then put an access cover outside. When I'm done, the tunnel would be
about 3' wide and extend 5' under the slab.

There are a few cracks in the slab elsewhere, but this entire area is
free of cracks. House is 50 years old.

Crazy to do this? If I don't I'm guessing my water heater, oven, and
three cabinets would have to be pulled to cut directly through the slab
and down to the break...not a pretty job.

I've been digging along the sewer line and have a 2' wide tunnel, about
13" under the slab, so far...so I have to ask, is this dangerous or
truly inadvisable? Would a pro consider this, and if so, would they be
shoring it up as they go, etc?

The digging doesn't bother me, actually it's kind of relaxing, but I
don't want to trash my house or kill myself or anything along those lines.

Please, unless you are familiar with the engineering/safety issues,
don't just automatically post negative. This is a real project, and I'm
moving forward with it, unless someone (knowledgable and experienced)
explains why this should not be done...and I would be very grateful for
that explanation, BTW!

You're welcome to email me at the reply-to account if you want to keep
your comments off the list.

Thanks,
Flash.