Moving under slab water pipes

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Macki

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I need to move a washer hot and cold supply that comes through the slab about 12”. It is 12” further away from its source, not closer to it. I suspect there is not going to be enough soft copper that is there already to just cut the concrete and bend it and have enough left to keep it above grade.
What is the best method for making an under slab splice?

Moving this here from the remodel section

Thank you,
 

WorthFlorida

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A picture will help. Do the hot and cold water lines come straight out of the floor in front of a what type of wall material? Can a 90 elbow be used to just extend it to the needed location? Is the pipe above the slab soft copper (not usual) or rigid copper (usual). I would extend the copper above the floor with elbows and put 2x2 furring strips and add drywall over the wood. Essentially extend this wall out 2" is it is all possible.

Soldered joints is best but need to be careful that the soft copper pipe maintains its round circumference. If there is a little bend it tends to go oval so you may have to cut back to get in the round. After the connection terminate the pipe and cap it off with a valve. Turn on the water to purge air and shut off the valves. Let it sit a few days to be sure there is no leak.
 

Macki

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Unfortunately no pictures until I tear down the wall. The soft copper is run under the concrete slab and simply arcs up through the concrete, through the sole plate and into the wall where it has fittings attached for the supply valves. The wall is being moved straight back 12”, making the existing supply lines 12” too short.
I need to add 12” to the existing lines. Sweat joints on under slab copper is not permitted on new construction, so I am unsure of what method to use to make a joint under the concrete slab. There is no moving it above grade as it would then sit in the middle of the floor.
 

Mliu

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First question: Are you sure the pipes under the slab are perpendicular to, and in front of, the wall that's being moved back? If coming from a side (parallel to the wall), you may be able to shift them over. If coming from behind, problem solved.

Second question: How far do the existing pipes extend up from the slab before they connect to the supply valves?
 

OLD TIMER

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when I lived in Phoenix, AZ. 10 years ago I had a city of Phoenix, Plumber/Gas fitters license and they required copper pipes be brazed
under slab. I've heard shark bites are allow but I wouldn't do it and don't quote me.
 

DW85745

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I'm in Tucson and just check with our building dept. and a brazed fitting is allowed under the slab.
They use the international standard. Makes sense since CU pipe comes in 20 foot sticks.
 

hj

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You DON'T use "sticks" under concrete. You use soft copper and roll it up into the walls and make the connections ABOVE the floor. You only use brazed joints when there is no other option, because brazing destroys the temper of the copper AND the fittings.
 

DW85745

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hj:
Just quoting City of Tucson Bldg Dept who cited International Code. Did Not verify or look up code.

You only use brazed joints when there is no other option

Which appears to be this case.

Don't have time for code lookup, but "K" Copper is for burial and is sticks.
Also did a quick search and found this. https://mybuildingpermit.com/sites/default/files/documentation/Plumbing Rough In.pdf
While not authoritative, it lends some support for using sticks.
Mueller would also go out of business if you could NOT have a joint under a slab.

But will yield to someone more knowledgeable than myself.
 
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Macki

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Perfect, not sure why I had not thought about a braze joint. That makes it easy enough.
 
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