A friend of mine is having some building work done. Just before the builders buggered off for the year, they back filled some pipe chases in the floor, and put a layer of self levelling over the whole screed.
Needless to say, no sooner had they gone, and a damp patch started to appear in one of the areas where they had filled in over some new CH pipework (so much for testing it first!) Turning the rad off seemed to stop the leak though. Suggesting possibly a pinhole that only opens when hot.
So muggings here offered to go and re-expose the pipes again to see if we could find the leak... much careful exploratory work with the trusty SDS got back to an (undamaged!) set of pipes. One had a wool style insulating jacket (possibly not a CH pipe, but might be the incoming cold main), which was rather damp - however other than that, no apparent direct source of a leak.
So other than the brute force approach of remaking every joint, any ideas for finding a vanishing leak?
(CH system is vented, header tank high enough to yield perhaps two thirds of a bar of pressure).
Just a thought but you have probably checked anyhow but could it be the small leak only occurs when cold (heating off) as the expansion when hot could seal it.
That might be workable... While it has the sniff of a bodge about it, it does seem like an attractive option in this circumstance. (especially seeing as it seems as if the leak has sealed itself anyway, it could be a backup to the good old south east England liquid chalk!)
Having re-exposed the pipes and not found any apparent leak, I went with the system sealer option... after a couple more days of no leak, decided it was safe fill in the floor chases again.
Guess what, few days later, floor is getting damp again, and the clock is ticking for when the job must be done.
So we go for the brute force approach this time; dig it all out yet again, and remake all the pipework in the area regardless, so we know all the joints are good. Although a suspicion is growing that we are chasing a phantom problem!
The original pipework was done with a mixture of soldered and pushfit, and mostly straight pipe - but under tension to bend round the other pipes etc. This also meant that it was in places very close to and in one place slightly above the finished floor level!
So plunge cuts with the multimaster to chop out the old stuff, some slip couplings etc, and a bit of creative pipe bending to get round the obstacles, corners, and other pipes later, we get:
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(several tedious hours on my knees to do all that! (not made any easier by much of the finish oak carpentry being added since the original fit))
Taped, trunked, sleeved etc all up and filled it in:
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Floor went in flat this time, and with a 1/8th inch gap under the oak to stop it being able to track water off the floor.
That was all good for a few days until, Arggggg! Wet patch again!
Wet brick...
Around the time of the second plumbing, there was also discussion of a very wet looking brick that had been exposed in the front wall of the house due to ground works on the driveway - it seemed odd - just one single brick that looked like it was saturated.
With the reappearance of the damp patch again, the particularly wet weather, and this new found feature, focus shifted somewhat to investigate other sources of wetness. The bods redoing the drive decided to excavate a bit near the wet brick and investigate. They found a half brick, and a half brick sized hole in the wall that looked deliberate - but the hole had been plugged with something. They pulled out the plug, and literally gallons of water poured out of the wall! Further investigation found another similar setup the other side of the front door as well. It appears as if the original builders in the 70's had created a couple of channels actually in the foundations of the house (but below DPC level) between the rear of the property and the front. Seemingly to allow the wetter rear land to drain toward the front. Presumably they had intended the water to soak away into garden in the front. The combination of the drive being laid a couple of years back, and the particularly wet weather now seemed to have overwhelmed that facility.
Anyway in conclusion. After unpluging, the damp patch dried out - so nothing to do with the plumbing in the first place. The driveway contractors arranged for both holes to be connected up to the drain they had installed for the drive so that there was somewhere for the water to go.
Can sympathise. When we extended the kitchen, we went down 18" and found water. We live on top of the hill! Thought about the situation and couldn't find a reason for the water as the nearest pipework was 15 feet away and there was no sign of water flow. So, carried on digging, installed the foundations and all was well. Decided that the problem was the water table was at that depth due to the clay soil. My neighbour
200' away decided to extend his house and found the same problem. He decided that he had a leaking water main and dragged out the water board who dug up the front, to discover that it was purely a water table problem. Subsequently the field at the rear of the houses was fitted with land drains to enable it to be used as a sports area and the water table has now dropped to about 3 ft.
However all the work was not wasted as the floor is now flat, not presumably bulged where the pipe was higher than the floor before.
I do have my doubts about pipes buried in concrete, but I suppose most of the time its OK. The saga you tell though would make me worried about what might happen to the land under the house if its all going to be a lot drier in the future due to the unblocked drain channels.
The pipe just poked out of the screed slightly! (it was very close to the door frame though, so chances are it would not have been too much of a problem in reality)
Concrete is known to attack copper slowly - so its wise to protect the pipe with something. I made sure the bits that went back were in a plastic lined felt wrap, or if depth prevented that, then a covering of gaffa tape.
Yes, its on Essex clay as well! It seems likely that the channels are actually over the foundation but below the screed - so it might not be contacting much soil.
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