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  1. #1
    Join Date
    Oct 2012
    Posts
    2

    Default Pipe Trench Repair

    Hi.

    My house is heated with hot water radiators fed from a boiler in through concrete trench through the middle concrete slab for the ground floor of the house and then back in a pipe trench along the perimeter of the house.

    The main supply line rusted clean through and for weeks (months? years?) has been dumping water under the foundation (fortunately near the outside. I just spent the last 48 hours breaking the floor and exposing pipe allow me to replace about 7 feet of pipe. Now that the repairs are all complete, I need to cover back up the hole in the concrete floor.

    Previously, the pipes were running in a hollow trench - about 8" tall and and 8" wide, in a bed of what looks like vermiculite or some sort of loose fill material. I know that the cement should come in contact with the pipes, so I am trying to figure out how to re-pack the new pipes put a 1-2" cement top back on to restore the floor.

    I was thinking maybe some loose fill around the pipes, then a piece of rigid foam over the top to create a base for the cement and then cover with a couple inches of cement?

    Any ideas?

    Thanks,

    Robin

  2. #2
    Join Date
    Jul 2010
    Location
    SoCal
    Posts
    5,081

    Default Re: Pipe Trench Repair

    Wrap the pipe with a plastic pipe sleeve, sold in plumbing supply outlets.

    I hope you can so a good repair so you don't have future leaks.

  3. #3
    Join Date
    Oct 2012
    Posts
    2

    Default Re: Pipe Trench Repair

    Thanks for the reply - I was hoping not to fill this entire cavity with concrete - it was a hollow space before, and if anything ever goes wrong, with another pipe in this trench, for example, it would be a major pain to have to break up that solid block of concrete again...

    Robin

  4. #4
    Join Date
    Jul 2010
    Location
    SoCal
    Posts
    5,081

    Default Re: Pipe Trench Repair

    You're right about that.

    They have been building with pipes in concrete for years. Usually it has been a safe practice, but when the pipes fail - it's a costly repair.

    Nowadays many repipe plumbers run copper pipes in attics and walls. At least that's what I do.

  5. #5
    Join Date
    Dec 2010
    Location
    Houston Texas
    Posts
    2,360

    Default Re: Pipe Trench Repair

    We remodeled a bathroom where the concrete had eaten the water supply pipe completely. The water ran through a hole in the slab for God knows how long.

    Sleeve the pipe. Vermiculite / perlite is a good idea as it insulates the pipe as well as provides some what of a foundation for the cement top layer. Use a bonding agent on the old ceement when prepping for the new ceement fill.

    Of course anything you can do to re-route the pipes out of the slab is a much better idea.

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