Slab House, Drain Line, What if?

[Donald Crockett]

Even though I would not “Do This Myself” I think this is the right forum.

Most of our properties are 3 bed 1 bath houses with slab foundations built in the 60's and they've done very well for us. We continue to look for properties that fit this profile. Basements around here usually have problems which are costly to remedy.

Now, I was watching a video of replacement of a drain pipe under a slab house. These guys actually hand dug a tunnel under the slab large enough for a person to crawl into all the way from the perimeter to the point where the pipe came down through the slab. That looks difficult and expensive.

I”m pretty sure that our houses have galvanized drain pipes. I think these pipes are prone to rusting internally and becoming slow, eventually stopping up completely. We've never had to deal with that. We have had some stop up because of convoluted, complex bends always accessible from inside the house but never had to replace a complete drain line.

My question is, if it comes to this, how is this usually addressed? The rooter guy says they can be cleaned with the rooter, the jetter guy says rooting doesn't work but they can be jetted and the plumbing contractor says neither of those will work they have to be replaced with plastic.

I'm not expecting any trouble like this but forewarned is forearmed. Does anyone here have any experience to share so I (and others) might be prepared with the knowledge should we be faced with this? Is it worth having the drains looked at with a camera when rehabbing?

[Don Meinke]

I just do it old school and be done with it.  If one pipe is bad chances are you might as well do all.  A concrete saw down each side or where it is cuts down on repour  and is much cleaner.  If you dont know exactly where it is going 4 to 6 foot at a time works good.  Make about a foot wide trench and dont dig below pipe bed so it settles and drops, dips,  and sways under pressure.  Smack the trench crete with a sledge and pick it out with a crowbar.  Carry out in wheelbarrow or 5 gallon buckets.  Here we can get a few half barrels of concrete mix at the redi mix plant off someones else batch,,,or mix own if a dab from 5000# premix from Menards.

  Make sure pvc pipe slopes about 2%.  Sink, shower, and laundry should all be upgraded to 2" pipe.  

  Same as changing out cast iron vent stacks as soon as possible.  Their are two kinds of metal pipes,,,those that leak,,,and those that are gonna leak (and plug up).

I have seen drain rotor rooter people charge more to rooter a drain than it would have cost to cut it off and put a new plastic one on that wont plug up.

but under slabs its 90% labor 10 % materials,,,and never never tunnel under one to fix anything,,,thats way past crazy.  How in the world you going to get soil as firm as it was,,,it will be hollow and cause more probs.