Copper pipe in a concrete floor

[Wowbagger]

16 years ago we had an extension built. It involved a long corridor/utility room copper pipes (H, C and central heating) were embedded in the concrete. In recent weeks we have had a very damaging leak that went undetected for some time: a pipe had a "pin-hole" in it, according to the leak detector man sent by the insurance company and attributed it to a duff piece of pipe. One of the blokes who came from GB Bathrooms (the leak was under the shower room floor) reckoned that copper would corrode if embedded without protection in concrete. No one else has mentioned this.

Given that this room is about 10 yards long and has pipes embedded alomg its entire length, I am concerned that, if he is right, another leak might occur, if one hasn't already. I have never heard this suggestion about copper corroding in concrete. Can The Panel please throw some light on the matter?

[Kim]

Embedding anything important in concrete seems like a daft idea to uneducated me.  Pipes, cables, bodies... it's only going to turn round and bite you in the end when chemistry or differential thermal expansion happens or the concrete cracks.  What's wrong with ducts?

Could you run smaller diameter plastic pipe inside the leaky one?  Probably more viable for heating than water supply.

[Gattopardo]

16 years ago we had an extension built. It involved a long corridor/utility room copper pipes (H, C and central heating) were embedded in the concrete. In recent weeks we have had a very damaging leak that went undetected for some time: a pipe had a "pin-hole" in it, according to the leak detector man sent by the insurance company and attributed it to a duff piece of pipe. One of the blokes who came from GB Bathrooms (the leak was under the shower room floor) reckoned that copper would corrode if embedded without protection in concrete. No one else has mentioned this.

Given that this room is about 10 yards long and has pipes embedded alomg its entire length, I am concerned that, if he is right, another leak might occur, if one hasn't already. I have never heard this suggestion about copper corroding in concrete. Can The Panel please throw some light on the matter?

Everything corrodes in concrete.

[Gattopardo]

Embedding anything important in concrete seems like a daft idea to uneducated me.  Pipes, cables, bodies... it's only going to turn round and bite you in the end when chemistry or differential thermal expansion happens or the concrete cracks.  What's wrong with ducts?

Could you run smaller diameter plastic pipe inside the leaky one?  Probably more viable for heating than water supply.

Even ducts, if metal can corrode and colapse

[LittleWheelsandBig]

Copper in concrete is fine, as long as chloride content is low and the concrete remains alkaline.

Reinforced concrete can crack if the reo corrodes. Galvanic corrosion between copper and steel can be a problem.

My guess is that differential thermal expansion might have bitten you at a bend or joint.

[Asterix, the former Gaul.]

16 years ago we had an extension built. It involved a long corridor/utility room copper pipes (H, C and central heating) were embedded in the concrete. In recent weeks we have had a very damaging leak that went undetected for some time: a pipe had a "pin-hole" in it, according to the leak detector man sent by the insurance company and attributed it to a duff piece of pipe. One of the blokes who came from GB Bathrooms (the leak was under the shower room floor) reckoned that copper would corrode if embedded without protection in concrete. No one else has mentioned this.

Given that this room is about 10 yards long and has pipes embedded alomg its entire length, I am concerned that, if he is right, another leak might occur, if one hasn't already. I have never heard this suggestion about copper corroding in concrete. Can The Panel please throw some light on the matter?

Everything corrodes in concrete.

Everything degrades everywhere!

However, it's a bit misleading to suggest that concrete is an exceptionally severe an environment.

Many boats have been made of concrete using steel reinforcing rods and their longevity is quite remarkable.  A lot of lighters were hastily knocked up in WW2 and many times longer than intended.  The oldest existing UK concrete ship was built in 1917.

Having said that  I think if I had to embed pipe in concrete I would use plastic pipe inside a conduit.  If the dodgy pipe is 15mm then it might just be possible to run a 12mm plastic pipe through assuming no nasty right angle bends.  12mm is adequate for supplying water to sinks and basins as well as CH.

Embedding anything important in concrete seems like a daft idea to uneducated me.  Pipes, cables, bodies... it's only going to turn round and bite you in the end when chemistry or differential thermal expansion happens or the concrete cracks.  What's wrong with ducts?

Could you run smaller diameter plastic pipe inside the leaky one?  Probably more viable for heating than water supply.

Even ducts, if metal can corrode and colapse

Doomed!  We're all doomed!!

[trickedem]

They should have used this stuff
http://www.denso.net/densotape. I have some pipes under my kitchen and was recommended to use this. 

Sent from my MotoG3 using Tapatalk

[Jaded]

We had a leak in a kitchen when underfloor heating had been put under concrete. The installer hadn't allowed for slight settlement from the new weight of the floor and a joint fractured.

[Canardly]

Denso tape as above. Burying of copper heating circs in screed was (and probably still is) very common. Not best practice but very common. More usual to employ service ducts nowadays for a new build or to run surface mounted. My own house has central heating circs buried and at least one gas pipe which is a pain if you want to move a rad or make kitchen layout alterations.

[innesh]

I'm afraid you already know the answer - it has to come out! I am not a plumber, just a few years ahead of you in experience.

It's just as likely that the copper has corroded from the inside, not from the effects of the concrete. If it is internal corrosion you can expect another pin-hole to appear before long. I've heard and read stories of cheap Chinese copper being at fault - recycled copper, inclusions in the metal etc. - starting from around 20 years ago, but who knows? We are on soft, spring water and (some) copper simply doesn't last with us. I had to replace our incoming cold main as it sprung a leak 2 foot below a concrete floor which was seeping from the external wall. It's not buried now!

Copper should always be protected in concrete -  Denso tape, plastic coating, ducting, foamed insulation - whatever separates the two and preferably allows for expansion. It's common sense that everything should be ducted and accessible - it's so easy in a new floor but a nightmare in an existing floor. I am currently looking at channelling about 2m of hot and cold pipes in a concrete floor (to save about 12m of convoluted pipe run) - it will be 15mm plastic pipe threaded through 22mm pipe with no hidden joints.

We're having some work done soon and part of that will involve replacing all copper water pipes with plastic. And no pipework in the loft! A ground floor leak is bad enough but ceilings coming down is worse. All our heating pipes are already plastic but also buried in concrete and there must be at least 12 joints buried in there- I have a feeling that eventually the carpets will be coming up there too, but it's lasted 28 years without any problems.

Wow, your problem is easily fixed but it's the disruption and expense that seems daunting, I know.  Bloody concrete floors!

[Ian H]

I have seen a copper pipe, said to be inferior quality, which had thinned inside to the point of splitting.  I suspect any solution is going to be disruptive, so probably best to fix it properly. 

[Aunt Maud]

I reckon it's thermal expansion like LWab says.

If you were handy with a router and your skirting is tall enough, you could hollow out the rear of the skirting and the wall behind it and lay new pipes behind that, leaving the old pipe in the concrete floor.

[orienteer]

Surely best just to abandon the buried pipes and instal new ones externally. You could box them in with wood, or plastic, if you don't like the sight of bare pipes.

[rogerzilla]

...is what I'd do.

My parents had a similar problem in the kitchen of their old house, after only a couple of years of the pipes being installed.  Never had internal corrosion of pipes personally; I've mostly lived in hard water areas where they get nicely lined with green scale after a short period of use.  Dezincification of brass, yes; I had some bathroom taps where the innards crumbled to pink pieces when I tried to change the washers after a few years' use!

[Polar Bear]

As we've been doing major works on the internals of our house we've been careful to put piping and wiring in accessible places where possible.   It makes for much easier maintenance in the future.

I'd agree with recent opinion and abandon the pipework entombed in concrete if you can.

[Jurek]

Surely best just to abandon the buried pipes and instal new ones externally. You could box them in with wood, or plastic, if you don't like the sight of bare pipes.

This.
And sleep easy.
Just a thought....

[Asterix, the former Gaul.]

...Bloody concrete floors!

Is there anything inherently wrong with a well-laid concrete floor?  Assuming nothing vital is buried in or beneath it? 

I do know the adage : 'there are 2 kinds of concrete, cracked concrete and concrete that is about to crack', but other than that?

[Kim]

...Bloody concrete floors!

Is there anything inherently wrong with a well-laid concrete floor?  Assuming nothing vital is buried in or beneath it? 

They can be quite annoying when you have a thing that you'd like to be buried in or beneath it...

[Zipperhead]

...Bloody concrete floors!

Is there anything inherently wrong with a well-laid concrete floor?  Assuming nothing vital is buried in or beneath it? 

They can be quite annoying when you have a thing that you'd like to be buried in or beneath it...

Normally the bodies should be dropped in while the concrete is being poured (see Hammersmith Flyover allegedly)

[Kim]

Exactly.  Same goes for the comms ducts (see "Why is my WiFi a bit shit?" threads passim).

[Asterix, the former Gaul.]

...Bloody concrete floors!

Is there anything inherently wrong with a well-laid concrete floor?  Assuming nothing vital is buried in or beneath it? 

They can be quite annoying when you have a thing that you'd like to be buried in or beneath it...

Normally the bodies should be dropped in while the concrete is being poured (see Hammersmith Flyover allegedly)

Having laid a concrete floor or two, I'd suggest making provision for any bodies well before pouring the concrete.  Thus avoiding quality control issues.

[rogerzilla]

https://en.wikipedia.org/wiki/Loch_nan_Uamh_Viaduct#Horse_inside_viaduct

[Aunt Maud]

I hear LWaB has a suspiciously large patio in the garden.

[LittleWheelsandBig]

Oi, zip it! I don't need no heat round 'ere.

[Wowbagger]

And back to square 1! The Man came yesterday to check the moisture levels in the walls and floor. We have had an industrial dehumidifier (satisfyingly supplied by a company called CDC - ... Drying Company) running almost non-stop for about 6 weeks and the plaster has been stripped from the walls. The Man has previously opined that the walls were drying nicely but the floor was taking its time. This is still the case, and it shouldn't be. Lo and behold, The Man lifted one of the chip boards that had been used to cover the trench dug by the first Leak Repair Man and there was a puddle in it.

This was, of course, on a Friday afternoon.