Adding New Sewer Line Under Existing Slab on Grade

Discussion in 'Plumbing Forum, Professional & DIY Advice' started by Indie6, Mar 8, 2011.

  1. Indie6

    Indie6 New Member

    Mar 8, 2011
    I want to start by saying i have read enough posts to know I need to read some more...

    Situation - I am in the middle of escrow on a 60 year old house and just finished with the inspections. The house is long and narrow and on a slab on grade. The sewer lateral runs down the back of the house and back up the other side towards the front of the house, making it about 250' long. Picture a long narrow "U" with a tail off of the top right leg. There are bellies and standing water, and I have been quoted $17k for the removal, replacement with cast, demo of the existing deck aand colored/stamped concrete steps.

    What I would like to do is eliminate about 100' of the line by re-sloping the lines in the back of the house to meet in the middle, essentially creating a "V", and then routing the line under the house and re-connecting with existing before it reaches the street. The proposed new route would not go under any bearing walls except 1 exterior wall. It would go under the bathroom walkway, through the doorway, across the hall and through another doorway - so I'm pretty sure I wouldn't have structural issues. The slab at this area is only 14' wide from one side of the house to the other.

    If I routed it this way I would avoid removing the colored concrete and most of the deck. I plan on making an addition where I would demo the deck.

    The problem - the slab has radiant heat tubing throughout, and I want to keep the system. It's all copper, so if I had to cut the slab I could fix it. But that just seems like more work than what it's worth.

    The question - What's the safest and best (not cheapest) way to achieve my goals?

    I'm a nail bender by trade so any and all info with this is much appreciated.
  2. hj

    hj Moderator & Master Plumber Staff Member

    Aug 31, 2004
    Cave Creek, Arizona
    It would definitely be an advantage to reroute the drainage in the most direct manner possible. Forget the radiant system. The cost to "patch it together" would be prohibitive.
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  4. Indie6

    Indie6 New Member

    Mar 8, 2011
    The expansive radiant heating system is one of the best attributes of the house. Why should I just throw it away?
  5. SacCity

    SacCity In the Trades

    Mar 14, 2011
    Sacramento, CA
    Repair of the copper lines for the heating system would be difficult, which means expensive. If you can route around those then great, but if you have to cut them then add the repairs into the cost or abandon the use.
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