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I am looking for any gotchas or obvious issues with below:

Discussion in 'Plumbing and Central Heating' started by Useroftheforce, 5 Feb 2014.

  1. Useroftheforce


    30 Oct 2008
    Thanks Received:
    United Kingdom
    I am looking for any gotchas or obvious points I might have overlooked in the following plan:

    I’ve never done floor digging and repairing before, or burying pipes – but done plenty of DIY and plumbing so reasonably confident.

    I am replacing a concrete buried 15mm copper pipe + compression joint (bad) with single 22mm polypipe runs – to service my bathroom.
    The feed comes under the floor in the adjacent room (via a cellar) and then disappears into concrete (screed) where the bathroom wall starts and then travels under the builtin shower. There appears to be no sleeving or protection for these pipes from the concrete in which they are encased.
    I have no plans to remove to shower and the floor under it to get to the existing pipe that would be a huge undertaking.

    So the plan is to remove the floor covering in a suitable location. Cut two slots around 75mm deep by 100mm wide in the concrete floor to accept the new pipes. Dig it / smash it out.
    Lay the polypipe into the hole and sleeve it with hessian (I bought this before I knew about the coated polypipe – but read that polypipe is benign in concrete in any case.)
    The pipe needs to make one 90 degree turn – which should be as tight as possible so I plan to attach a cold forming bend for each pipe to achieve that.
    I read that hot and cold feed pipes should be 50mm apart – hence the 100 mm cut width and they should be at least 50mm deep, hence 75mm depth.

    Does that all sound ok, or are there some issues I need to be aware of?
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  3. Agile


    26 Jun 2004
    Thanks Received:
    United Kingdom
    I would never bury hessian in concrete.

    I would use the foam plastic insulation! For both insulation, expansion space and for protection from the concrete ( although plastic pipe does not need it ).

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