Is it ok to put pipes under concrete

Is it OK/normal to put copper central heating pipes under insulation and then concrete screed on top. Does it comply with UK Building regs.
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  • BlueC
    BlueC Posts: 734
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    Sounds like a bad idea to me. What happens if you need to service them or if a joint goes? You going to dig up the floor?!
  • alanobrien
    alanobrien Posts: 3,308
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    It is normal in as much as its been common practice for years to put central heating pipes under concrete floors but its a very very bad idea from a maintenance perspective. If you have just one joint go you have to dig up the floor to fix it, and that can be after a costly exercise to find the leak in the first place. Then consider if it leaked once it could leak again so the experience could be repeated again at anytime.

    I just re-piped our central heating system from upstairs to downstairs using drop downs for this very reason.
  • southcoastrgi
    southcoastrgi Posts: 6,298
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    you can with heating pipes providing they are protected, however as above it's not a good idea, the pipes expand & contract & will wear through the copper, potable water pipes have to be accessible therefore the water regs don't allow these to be buried in concrete/screed/plaster
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  • Avoriaz
    Avoriaz Posts: 39,110 Forumite
    edited 16 June 2013 at 2:22PM
    We had a kitchen extension built in 1993 with copper pipes buried in the concrete floor. We kept the softener in its original location under where the sink had been by the rising main and the builder's plumber ran three copper pipes for hot, hard cold and soft cold pipes to the new sink location about two metres away. A further copper cold pipe fed the rear garden tap.

    After about 10 years the cold water pipe feeding the garden tap, which ran the full length of the long kitchen extension, failed and started to leak.

    We didn't notice until water started bubbling up through a join in the vinyl flooring. By that time a large area of concrete was saturated and it took weeks with a noisy dehumidifier and fan to dry out the floor. We had to lift half the vinyl, which thankfully we were able to reuse, and live with the noise and mess for weeks.

    I isolated that pipe under the sink and replaced it with a plastic pipe that I ran under the kitchen units.

    A few years later another pipe failed and we had the same problem again.

    I dug up all three copper pipes and replaced them with plastic pipes run in a plastic flexible conduit.

    The pipes had all been properly wrapped in insulation but had still been corroded by acids or alkalis or whatever was in the concrete.

    Our insurance covered all the costs on both occasions but I still would not to go through all that again.


    My advice is to avoid running copper pipes in concrete if possible.

    Can you use plastic pipe in plastic conduit instead? That means you can have one continuous run with no joints and the plastic pipe should last indefinitely. If it ever does need replacing you will probably only have to dig out at either end and feed new pipe into the conduit.

    I don't know what the current building regulations require.
  • anotherbaldrick
    anotherbaldrick Posts: 2,335 Forumite
    edited 16 June 2013 at 2:56PM
    Avoriaz.
    The pipes had all been properly wrapped in insulation but had still been corroded by acids or alkalis or whatever was in the concrete.

    Insulation is the wrong material to protect copper pipes in concrete or cement screed. It allows the passage of alkaline moisture to get to the copper. You need a specific waterproof wrapping like Denso tape, vile stuff to work with... If at at possible dont bury pipes, copper or not.http://compare.ebay.co.uk/like/400146706091?var=lv&var=sbar&_lwgsi=y&cbt=y&device=c&adtype=pla&crdt=0&ff3=1&ff11=ICEP3.0.0&ff12=67&ff13=80&ff14=66
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  • Jonesya
    Jonesya Posts: 1,824
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    I'm not a plumber so this is only a suggestion but could you install some plastic conduit or piping into the concrete to provide a duct and then run something flexible like micro-bore through it?

    Plastic is inert and resistant to the concrete and provides some flexibility to replace the pipework in the future.
  • vaio
    vaio Posts: 12,287
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    Avoriaz wrote: »
    We had a kitchen extension built in 1993 with copper pipes buried in the concrete floor. We kept the softener in its original location under where the sink had been by the rising main and the builder's plumber ran three copper pipes for hot, hard cold and soft cold pipes to the new sink location about two metres away. A further copper cold pipe fed the rear garden tap.

    After about 10 years the cold water pipe feeding the garden tap, which ran the full length of the long kitchen extension, failed and started to leak.

    We didn't notice until water started bubbling up through a join in the vinyl flooring. By that time a large area of concrete was saturated and it took weeks with a noisy dehumidifier and fan to dry out the floor. We had to lift half the vinyl, which thankfully we were able to reuse, and live with the noise and mess for weeks.

    I isolated that pipe under the sink and replaced it with a plastic pipe that I ran under the kitchen units.

    A few years later another pipe failed and we had the same problem again.

    I dug up all three copper pipes and replaced them with plastic pipes run in a plastic flexible conduit.

    The pipes had all been properly wrapped in insulation but had still been corroded by acids or alkalis or whatever was in the concrete.

    Our insurance covered all the costs on both occasions but I still would not to go through all that again.


    My advice is to avoid running copper pipes in concrete if possible.

    Can you use plastic pipe in plastic conduit instead? That means you can have one continuous run with no joints and the plastic pipe should last indefinitely. If it ever does need replacing you will probably only have to dig out at either end and feed new pipe into the conduit.

    I don't know what the current building regulations require.

    I'd agree with not running pipes in concrete but on the other hand, my dad's went in in the mid '70s....flow & return heating plus gas. Gas was plastic covered copper pipe with the joints wrapped in denso tape, heating was just bare copper with the old split insulation. 40 years on he has had no problems. Maybe it's a different concrete mix?
  • Leif
    Leif Posts: 3,727 Forumite
    I don't see how you can have joint free pipe. I have multiple radiators on several stretches of pipe, 3 in one case, 2 in another case. You can have pipes in the walls, or in the screed. I have plastic in screed, I only hope it lasts. Exposed pipes looks really naff in my opinion, which is why I paid to have pipes put back in screed. The original pipes were copper in screed, and I think they leaked. I think digging up a pipe from screed is less disruptive than digging it out from a wall.

    Some people place pipe in pipe, and have junction boxes with removable covers. One person I know raised the floor, creating a false floor above screed, and placed copper pipe below the false floor. It sounds a good idea, but doors will be less than standard height, and cheap doors won't fit as you cannot take much off, so you'll have to have more expensive ones. Protected pipe in screed has the advantage of being cheap, and it seems to work.
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  • Avoriaz
    Avoriaz Posts: 39,110 Forumite
    vaio wrote: »
    I'd agree with not running pipes in concrete but on the other hand, my dad's went in in the mid '70s....flow & return heating plus gas. Gas was plastic covered copper pipe with the joints wrapped in denso tape, heating was just bare copper with the old split insulation. 40 years on he has had no problems. Maybe it's a different concrete mix?
    I think Sir Baldrick has the answer to that one.

    Your dad's pipes were protected by plastic. Mine were just wrapped in brown insulation.
    Insulation is the wrong material to protect copper pipes in concrete or cement screed. It allows the passage of alkaline moisture to get to the copper. You need a specific waterproof wrapping like Denso tape, vile stuff to work with... If at at possible dont bury pipes, copper or not.http://compare.ebay.co.uk/like/400146706091?var=lv&var=sbar&_lwgsi=y&cbt=y&device=c&adtype=pla&crdt=0&ff3=1&ff11=ICEP3.0.0&ff12=67&ff13=80&ff14=66
    I know that now.

    I didn't know that in 1993 when we hired the builders. I thought they would know what they were doing. :(
  • Dukesy
    Dukesy Posts: 406 Forumite
    Don't do it!

    In the course of our current renovation, we have dug up a multitude of pipes from under the concrete of the floors, ALL of which were leaking, and clearly had been for some considerable amount of time. The damage that this had caused was enormous - you could literally poke your finger through the plaster on the walls in the bathroom, and the place stank to high heaven.

    The leaks may just have been due to poor workmanship, as when we dug the sewage pipe up, we found that too was leaking, not due to a failed joint, but because someone had simply propped about half an inch of small pipe into a big old clay pipe at an angle and then just hidden it in concrete. If you flushed the loo and ran to the other side of the room, you could watch the water go past through the gap.

    However, we have made sure that when we replumbed the place, all the pipes have been placed so they are either accessible or at least bypassable. The only exception is the sewage, which HAD to go under the floor, but as we did it ourselves, we know it hasn't been bodged up and then hidden under concrete.
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