Embedded Combinations and Corrosion...

[Batpig]

Hi Blokes,

I was talking to my plumber a while back about the proposed renovations at the Flat, and he casually mentioned that the type of building that I’m in (ie. 1970's cavity brick, suspended concrete slab) are a bit of a "time bomb" with regard to the original copper water pipes, especially in cases where they’ve been tied off (without the use of lagging or conduit) to the steel reinforcement in the slab. After tracking down and reading another thread on the subject (http://www.woodworkforums.ubeaut.com...pper+%2Bcement), it sounds like you don’t even need the pipes to be in contact with the reinforcement to end up with problems - the cement alone can corrode them. Even pipework chased into a brick wall, and then backfilled over with mortar, sounds susceptible if it hasn’t been duct-taped or Kemlagged. I also remember the Plumber mentioning that the old brass in-wall combinations (do you Plumbers call them "Breeches"?) were particularly susceptible to corrosion failure.

Now imagine if you had just gone to all of the trouble of getting your Shower Recess all nicely waterproofed up, and then getting it and the Kitchen splashback all nicely tiled up (with a whole new kitchen as well I might add), and then having your remaining old water pipes let go somewhere down in the slab... What a nightmare!... I am therefore contemplating the preventative measure of running a new set of pipes externally around the outside of the Flat now, that duck back in where they need to hook up in both the Shower and Kitchen, before getting the said waterproofing and tiling done.

The Shower Recess and the Kitchen Sink are both on perimeter cavity-brick walls, with 50mm cavities. My Plumber likes single-lever Mixers, but I prefer good-old-fashioned separate taps, albeit Ceramic Disc. I think he likes the idea of Mixers because it gets the taps out of the walls, but there’s a couple of problems with using them in my case:

a) From what I can gather, it’s pretty difficult to install a Mixer into a cavity-brick wall (as would have to be the case in the Shower).

b) The Kitchen is fairly small, so I want to retain the existing 450mm deep (from front to back) "Star" style sink (try saying that very quickly three times...), which doesn’t really have any dedicated spot anywhere on it for drilling a hole through which to install a Mixer (or any other tap for that matter), thus necessitating another wall installation.

The way I see it, the new external pipework (two separate pipes at each location - Shower and Kitchen) would come in through the inner brick leaf perpendicularly. My questions are:

1) What would the pipes then have to do to be able to hook up to an in-wall Combination? - ie. Would they have to do a right angle turn and run up the wall for an inch or so before meeting the bottom of the Combination? Or could they somehow run straight into the back of the Combination? (as in, maybe you can install a couple of pipe stubs into the back of a certain type of Combination, and then poke them straight out through a couple of holes that are drilled through both leafs of brick as the Combination is sunk into it’s recess, and then do the hook up on the outside...)

2) What’s going to protect the new Combination from corrosion once it’s buried in the wall and mortared over? Kemlagging will obviously do the job for the pipe stubs, but can you buy Combinations that have been fully Kemlagged, or otherwise coated in some way (expressly for the purpose of being mortared into brick walls)?

The Combinations will then have to be tiled over in both the Shower and the Kitchen. I might also mention that I wasn’t wanting to go down the route of exposed chrome Combinations that sit proud of the tiling.

Any thoughts anyone?...

Many Thanks,
Batpig.

[wonderplumb]

Im doing a unit at the moment where Ive simply started again with new pipework.
Im more than comfortable to simply use lagged pipe for the hot and put the CW pipework in plain, I have never seen copper pipe corroded through from being cemented into a wall and would be happy to suggest it will outlast me.
Same with the shower mixer/recess tee/ breech what ever you like to call it.
It would be a good idea to start again and disregard the pipework in the slab while your at it.

[juan]

[quote]I have never seen copper pipe corroded through from being cemented into a wall and would be happy to suggest it will outlast me.[quote]

Totally agree. When I pulled the 50 year old hot and cold water copper pipes and breeches out of the cement render during my bathroom reno, they were as good as new with no corrosion.

[journeyman Mick]

............I have never seen copper pipe corroded through from being cemented into a wall and would be happy to suggest it will outlast me...............

I've seen heaps of it corroded through, mostly where it's been embedded in slabs, but also where it's been chased into walls and mortared in. I've seen probably 20 - 30 jobs like this and I'm not even a plumber.

Mick

[Batpig]

Thanks so far Fellas,

Mick, it sounds like Wonderplumb agrees that concrete is bad news, but isn't too worried about mortar.

Wonderplumb, if I go external in order to safeguard against future failure in the slab, I might as well do the vertical bits externally as well (just in case), and just duck them back in horizontally at each Combination. It would have been nice to be able to get a Kemlagged Combo, but it sounds like you maybe can't get these things coated and ready to go, straight off the shelf. I guess they could be taped up, though...

I was at my brother's place yesterday (helping him dig a platform by hand for his proposed shed...), and he reckons an exposed chrome Combination wouldn't look too out of place. Do any of you know of a company that specialises in this sort of thing? Last time I was looking for one, they weren't exactly growing on trees...

Thanks again,
Batpig.

[wonderplumb]

I've seen heaps of it corroded through, mostly where it's been embedded in slabs, but also where it's been chased into walls and mortared in. I've seen probably 20 - 30 jobs like this and I'm not even a plumber.

Mick

20 or 30! Wow!
Ive seen plenty in a slab that have failed and Ive had to fix and of the ones mudded into the wall that ive had to fix have resulted from poor workmanship in the beggining, never 'eaten' through by sand and cement, and in all instances the pipework has cleaned up with minimal fuss with no signs of corrosion.

[davo2310]

I agree with wonder, the only pipework in units Ive had to replace is all light gauge rubbish.




Was this the type of shower set you meant?






http://www.reece.com.au/bathrooms/products/2251867

[journeyman Mick]

20 or 30! Wow!
Ive seen plenty in a slab that have failed and Ive had to fix and of the ones mudded into the wall that ive had to fix have resulted from poor workmanship in the beggining, never 'eaten' through by sand and cement, and in all instances the pipework has cleaned up with minimal fuss with no signs of corrosion.

I was told that there was some dodgy copper back in the 70's but have never seen any corrosion problems with pipework in timber stud walls from the same period. Perhaps the copper was just more susceptible to corrosion especially when in contact with cement based products. Last one was a bathroom and the combination was green with corrosion and full of pinholes.

Mick