I read an article saying that copper will resist corrosion if laid in a
portland based concrete or mortar. Could someone explain why, and what is
the alternative to portland that WOULD corrode copper? (Sorry, my knowledge
of chemistry never was a strong point).
Don't lay copper pipes in concrete full-stop. They will eventually corrode
even if plastic sleeved. Where the pipes are joined (and there will be
joins), you will find it difficult to seal and the 'fat' of the concrete
will find its way onto the pipe causing the said corrosion.
There is a small council housing estate near to where I live with the CH
pipes buried in the concrete and after about 10 years, these started to leak
causing me to have a few grey hairs in trying to sort it out - the only cure
was to re-pipe all the systems above floor level. BTW, most cements used in
these conditions are OPC (Ordinary Portland Cement)
If you MUST lay pipes in concrete, consider using plastic - if want my
opinion - don't even do that!
Just what I want, long lengths of piping running around the skirting.
My FiL's new house has all concrete floors with the pipes (micro-bore)
My house has never had a leaking pipe in 20 years. Does the screed really
'leak' onto the pipes to cause damage?
I'm going to go with buried pipes. If they last 10 years, good. If they last
more than 10 years, even better. If they leak, isn't that what insurance is
All I can say is what I experienced on this particular site. The houses
were built in the 70 - 80's and are of a No-Fine concrete construction with
a standard concrete base with a 2" screed/tiled finish with the plastic
sleeved copper pipes buried between the both.
The problems first arose around the end of the 80's with damp patches
showing on the floor in just one house. When the pipes were exposed,
corrosion was found around the area of the pipes that were joined using
end-feed soldered fittings which had NOT been very well protected after this
When we investigated further, pipe corrosion was found upto a foot a way
from the fitting and UNDER the protective sleeve (the ends of this having
been softened when heat was applied to the joints) - which indicated that
some of the 'fat' from the screed/concrete had somehow founds its way under
After this problem raised its ugly head in about 10 or 12 properties (with
the resulting insurance claims by the tenants), it was decided to fit new
heating systems and bring all of the pipework above floor level.
With regards to the "Gas copper pipe" you were talking about. If I remember
this came in very long rolls of copper with a yellow plastic sleeve, I would
presume that this was laid 'joint free' thus leaving the sleeve intact over
its entire buried length - in our case, the heating pipes were of standard
lengths and then jointed as needed. And that WOULD make a difference.
So what you are actually saying is that the pipes weren't protected. We
all agree that unprotected pipes will corrode. I think your story says
more about the competence of the original builders than the longevity
of copper pipe.
No I am NOT saying that the pipes were not protected - please re-read the
What I said was that where the pipes had been joined, the joint area was NOT
VERY WELL protected after the soldering - and along with the softening of
the *plastic sleeve* caused by heat from the soldering torch, allowed the
concrete 'fat' to run into places that it shouldn't have.
With regards to the builders incompetence: you are only partly right there,
more incompetent were the architects and the CH designers for allowing the
pipes to be buried between the site concrete and screed in the first place
with any form of joints in them - and the Clerk of Works for not spotting
the pipe protection problem at the joints *before* the screeds were laid.
Any cement will eventually corrode copper this is bacause of the lime
used to make the cement !!
If you need to run a copper pipe through cement run it through
a plastic one first !
Or just use the new plastic flexi pipe which takes hot or cold wate
will not corrode..
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