Help! Eroded concrete found under kitchen floor

[Eric Anderson]

Hi,

I am in the process of replacing floor tiles with engineered wood in the kitchen of the house we're moving in to. However, lifting the tiles under where a towel rail had been installed we found a nasty surprise. The pipes appear to go through a concrete slab, but around the pipes there's now loose rubble coloured brownish red around them - see pictures.

I am hoping that this is from water coming of whatever the previous owners had hung on the towel rail, rather than from the pipes themselves. There are also signs of corrosion on the outside of the towel rail (that has now been removed). Does this sounds like a reasonable explanation?

I've since lifted the loose rubble from around the pipes and now have two holes an inch or so deep around each - what do I use to fill this space before laying the engineered wood flooring?

Many thanks,
Eric

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• Eric Anderson
• 28 Jun 2015

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• Eric Anderson
• 28 Jun 2015

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• Eric Anderson
• 28 Jun 2015

 

[Newboy]

Wrap tape around the tails and then float in leveling compound. I'd be more concerned that the rad valves are leaking - both appear to have been turned away from their original position and both pipes look damp. Very evident in your last photo.

 

[Eric Anderson]

Thank you, what type of tape would you use for this, and what is the purpose of the tape?

The towel rail was recently removed and the valves capped as the connection between the radiator valve and the radiator was leaking. Plan is to replace the radiator valves on both sides and get a regular radiator installed.

 

[Bosswhite]

The first thing you need to do is clean away around the Pipes and find out why the tails are not in their proper position.
You could have a couple of leaks under the floor, looks like someone has used Brute Strength instead of a pair of pipe wrenches to remove Towel Rail

 

[Eric Anderson]

So, the towel rail was connected on the outside rather than inside the pipes. The left is facing the same way as it was while the right was turned to allow the rail to be forced off the floor (screwed down with screws where the screw head was corroded and useless).

 

[Bosswhite]

I would check the pipework of the tail on the right then,
If the plumber originally used a pipe bender or spring to bring the tail up through the floor the odds are the pipe will be buckled, if he used a compression fitting it will have moved and leaks, again with a solder joint the solder seal could be broken

 

[AlanE]

If the copper pipes were embedded in the cement what you are seeing could well be caused by water leaking from badly corroded pipes.

 

[Eric Anderson]

So, I've done some more digging (literally). The tails have been bent and look fine, but under the cement (now rubble) I found two compression joints in not too great shape. Do these look like they may be the cause?

This is now beyond what I'm comfortable addressing myself, but what would be the fix here, drain the system, replace the joints and pull up new pipes? Can compression joints be used this way again or do they need to be soldered?

 

[Bosswhite]

Try giving the old compression fittings in the concrete a "nip" with a couple of pairs of water pump pliers, they may just need a tighten up.

 

[Eric Anderson]

So is the fact that they look the way they do a sign of there being leaks from them? Or them having been wet from elsewhere? Or do they look "normal" and the only reason to believe they're leaking is due to the concrete being eroded around them?

 

[AlanE]

The compression joint doesn't look that bad but the pipe under the floor seems distinctly suspect and looks like it might have been weeping. Unfortunate result, all to often, of directly burying copper pipe in concrete.

You have started this job so why not continue?

Chop out the concrete out from around the pipe. If you are wanting the heating system reinstalled in the same place the relay the pipes but this time either in a duct so the pipes are isolated from the concrete or use plastic pipe, must be 'barrier' type contained within a plastic conduit.

 

[Eric Anderson]

Thank you, I'm new to all this so not sure what you can expect the joits and pipes to look like.

So that I understand, how can you tell that pipes have been weeping? From the damage to the concrete or looking at the pipes themselves?

 

[joe-90]

Dig it all up and replace it. Sheath it in plastic pipe. Did a job just like it a fortnight ago. If you ever get a combi boiler you'll be forever topping it up.

 

[RigidRaider]

In your first picture the darker pipe to the right of the compression joint looks badly corroded. Also, why is the body of the joint corroded and not the nuts? They should all be brass. The alkalinity of the concrete has attacked the metal in the presence of moisture, and since those pipes are warm pipes, where is the moisture coming from? Is the damp coming from somewhere else under that wall? I would take it all up and start again. Now is the time to be draining your heating system and while you're at it, take the opportunity to fit a drainoff valve and pipe at the lowest point, not one of those stupid little drain cocks with a bleed screw; use a proper gate valve.

 

[AlanE]

Thank you, I'm new to all this so not sure what you can expect the joits and pipes to look like.

So that I understand, how can you tell that pipes have been weeping? From the damage to the concrete or looking at the pipes themselves?

Years of experience! Colour/condition of pipes, wet concrete. (Bear in mind opinion is result of looking at a photo not a real life examination)