Extending copper lines under slab

Discussion in 'Plumbing Forum, Professional & DIY Advice, Tips & ' started by cruiser, Nov 30, 2011.

  1. cruiser

    cruiser Member

    Messages:
    46
    Location:
    California
    Hi Folks,

    I have a hot water tank whose housing (marked A in photo) is currently protruding into what will be our new kitchen(access to tank is on outside of house)The supply to and from the tank is via copper piping under the concrete slab(bottom left). I wish to move the tank from its present location to a new housing on the exterior of the house.(marked B on photo)

    In order to do this i need to extend these copper lines under the slab (from bottom left of photo) to the new location which is approx 4 feet from current one popping up from slab below where the outlet currently is). I'm concerned about a future leak at the point where I extend the pipes. I have replumbed a previous house from galv. to copper and had no leaks but would be anxious about this procedure as it will be under slab/then hardwoods. What steps, if any can I take to decrease the likelyhood of wishing I never did this :)

    Thanks for any and all advice

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  2. bluebinky

    bluebinky Member

    Messages:
    393
    Location:
    Santa Clara, CA
    If you can, make all the soldered connections above the slab. Braze (not solder) those below.
  3. Widdershins

    Widdershins New Member

    Messages:
    7
    Location:
    Washington State
    Use soft "L" copper to loop under the slab and then make all soldered connections above the slab. Piece of cake.

    As added insurance, insulate the loops under the slab with closed cell pipe insulation to protect the piping from coming into contact with debris in the backfill.

    At a minimum, you should wrap the copper piping with 10 Mil PVC pipe wrap to avoid contact with the concrete when you exit the slab.
  4. hj

    hj Moderator & Master Plumber Staff Member

    Messages:
    26,618
    Location:
    Cave Creek, Arizona
    I assume that means you are going to "eliminate" the wall where the copper lines are now, otherwise you could just reroute them around the corner above the slab. To extend copper lines under the floor you can ONLY use flare fittings or brazed connections and your torch is not hot enough to braze that size copper. IN addition, brazing "overheats" the copper and fittings softening them and making them MORE susceptible to fracture under stress.
  5. Widdershins

    Widdershins New Member

    Messages:
    7
    Location:
    Washington State
    True dat.....

    I wouldn't bother brazing anything under 1".
  6. cruiser

    cruiser Member

    Messages:
    46
    Location:
    California
    Thanks for the replies folks,

    hj...............That wall where the pipes are now is coming out and will go back to the exterior wall marked 'B', so I will have to extend pipes under the slab. I'm thinking flare fittings are the way to go as I have never brazed before and from what you say may not be the better option for me in this situation.

    So flare fittings to join the pipes, insulation around the pipes and pipe wrap as they exit the slab is looking as my likely course. Gotta practice my flare fittings as I never used them before, I'll rig up some pipe and join with a flare fitting and run the water through her.

    Thanks again

    Thanks
  7. Yersmay

    Yersmay Writing, constructionDIY Member

    Messages:
    62
    Location:
    Los Angeles
    flare fittings

    I'm curious to learn more about flare fittings. Could one of the pros describe how this is accomplished and perhaps even post a picture of the tool used to accomplish this? Is a flare fitting soldered as well? Thanks in advance.
  8. cruiser

    cruiser Member

    Messages:
    46
    Location:
    California
    Tips on using flare fittings would be fantastic. One last question I have a roto-hammer and can chip away to open the slab but would it be better to rent a concrete saw to make a clean cut?

    My conflicting thoughts are;

    1) If I chip away at the slab using the roto, will the constant vibration damage the nearby pipes or
    2) if I use a concrete saw will that make it harder for the new concrete to adhere to the clean cut when the work is finished and it's time to cover it up.

    decisions, decisions :)
  9. dlarrivee

    dlarrivee New Member

    Messages:
    1,172
    Location:
    Canada
    Either or, I would use what you already have.

    Use a bonding agent when you pour the new concrete to the old, and dampen the soil too.

    If you're careful a chipping hammer wont damage anything.
  10. ballvalve

    ballvalve General Engineering Contractor

    Messages:
    3,261
    Location:
    northfork, california
    First you score the slab with a skil saw and a 10$ diamond blade, use a hose for water and get the kid on the wet vac. THEN you very easily break out the section with the roto hammer. Score it deep enuf and a hammer works too.

    I would silver solder the joint. You might be able to find the old cast brass couplers with deep sockets that had a hole for filling near the joint. Last forever.

    If you are still worried, put plaster of paris over the joint area. And sleeve the pipe for corrosion, or run a pipe sleeve to outside, so any leaks dont show in the house.

    Here is an interesting 'coupler' that you can cut to length, thus making one much deeper than standard.

    http://www.accentshopping.com/product.asp?P_ID=149071
    Last edited: Dec 4, 2011
  11. dlarrivee

    dlarrivee New Member

    Messages:
    1,172
    Location:
    Canada
    As usual ballvalve's suggestions are not code oriented and are unorthodox.
  12. ballvalve

    ballvalve General Engineering Contractor

    Messages:
    3,261
    Location:
    northfork, california
    This is one lemming that never went over the cliff.

    My how to cut a slab slot is as orthodox as a jew with 3' braided hair and a fur cap. Code? don't see that.

    Since your walls are filled with soldered couplers, and joints, why not one heavier and longer under the slab? Describe to me how a leak in the wall vs one in the slab is more problematic.

    Since this pipe terminated OUTSIDE, and should he know how to sleeve it, it would be the safest joint in the house. I can send you a link to my book "double wall pipe containment systems" in case no one gets it.

    Building the H-bomb, Apollo program, hybrid vehicles, the WWW, took a lot of unothodox thinking, something plumbers seem not to wish any participation in.

    Who is the copper GOD that decided a flare fitting is better than a solder joint? Advising a homeowner to attempt a flare fitting is fairly asking for disaster. Unles he fluxes it up first and then solders it too.

    .

    would one of you orthodox guys explain how a leak in his ceiling when he is in florida on vacation is more problematic than one in a tube that takes any [NOT] leaks outside?

    As to brazing, there are many alloys available, from 10,000 psi to 70,000 psi.
    Silver solder: 6000 to 12000 psi.
    So the brazing requirement is absurd, when any failure must occur in the pipe. Just because its hotter does not mean its stronger.
    Last edited: Dec 4, 2011
  13. Jerome2877

    Jerome2877 In the Trades

    Messages:
    397
    Location:
    BC
    Because the plumbing code says so! Its not that we can't think outside the box like you but we are restricted by code and when giving advice on a plumbing forum we will give advice that follows code.
  14. ballvalve

    ballvalve General Engineering Contractor

    Messages:
    3,261
    Location:
    northfork, california
    The "code" Nazi's are killing our trades because a house is becoming unaffordable with sprinklers, and the 30-40 $ breakers. Not to mention energy calcs and required engineering and its bizarre earthquake connections.

    Our septic permits went from 120$ to 480$ this year, and new houses require geologic testing-earth bearing tests! Yet I can put a mobile on 2$ pavers in a swamp.

    Yet in a quake, its all the government infrastructure that collapses, and the fat utilities didnt have to trim the trees or underground the power. And the "code" doesnt seem to enforce the proper inspection of natural gas pipelines, that are regularly barbequing entire neighborhoods. Seems like that inspection is a bit more important than a water pipe in a kitchen slab. But they have gaggles of lawyers and we have squat.

    We are heading to mobile homes as the first choice, and old houses will sell at a premium because no one will be able to afford a stick built house except the trustapharians and the wall street thieves.
  15. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

    Messages:
    21,995
    Location:
    New England
    Don't think you can flare rigid copper, only soft copper, so that may be out as an option.

    The reason we have codes is to provide a known, good, reliable, safe method of completing the task at hand. These generally have been tested both in a lab, by analysis, and in the field and proven to work. On your own property, you can make a determination, although it may be illegal, as to whether you will follow the rules just like you can decide if you'll stop at the stop sign or exceed the speed limit. Doing so may or may not be safe, but it is still illegal. The codes are designed for those 'what-if' situations, the average person either doesn't know, or thinks will never happen to him...just like those people that say I don't wear a seatbelt as I'm a great driver and never would need one then get hit headon by someone in the wrong lane, all mangled.
  16. ballvalve

    ballvalve General Engineering Contractor

    Messages:
    3,261
    Location:
    northfork, california
    We also have paper money, which was foisted upon us as a good and safe, reliable method of making transactions.... with absolutely no value except to bankers and the government that have granted themselves the right to bankrupt the earth with its unregulated games. At least coins have some residual value as copper and nickel and iron, but when the system crashes, all you can do is use your T-bills and cash as toilet paper and kleenex.

    I wear seatbelts, use that funny money, and follow most of the codes [buy a permit, that is] outside of minor projects. But one must judge when the codes have no value or are skewed, and break them. It would take very little for canned food and guns to become the currency of favor.

    I have been putting sprinklers in utility rooms for years, with a pat on the back of the inspectors. Building a rental under the old code, but added sprinklers with the understanding that they would sign it off as "not to code" - not doing the absurd tests and flow requirements. Real world conditions say that 95% of all fires are restricted to one head opening anyway.
  17. bluebinky

    bluebinky Member

    Messages:
    393
    Location:
    Santa Clara, CA
    This one is absurd. I've heard that many inspectors will look the other way as long as you don't make the final connection and it wouldn't cause a hazard if you did ("illegally") after they're gone.

    Hard to otherwise disagree with all the other code requirements I've been able to comprehend so far, though...
  18. cruiser

    cruiser Member

    Messages:
    46
    Location:
    California
    op here :)

    All my research indicates flaring for soft copper only, whilst I can use soft copper for the extension of the lines how do I join it to the existing copper assuming it's not 'soft', how would I know if it were?

    Thanks
  19. ballvalve

    ballvalve General Engineering Contractor

    Messages:
    3,261
    Location:
    northfork, california
    I hope you dont apply absurd to sprinklers in a utility room. Smoke detectors just get you outside to toast marshmellows. When they work.

    Never saw any prohibition of sprinklers prior to the new absurd laws. Doing "more" is rarely frowned on by inspectors.

    I have put a lot of hose bibs in bedrooms and near fireplaces, great for watering plants and saving a house when the christmas tree starts burning.

    Hardly absurd, along with my roof sprinkler with a 100' throw that left my house standing out of 27 burned in the last wildfire. Educated a lot of firefighters that next smouldering day. If I charged for the photos they and the film crews took, I would be a millionaire.
  20. bluebinky

    bluebinky Member

    Messages:
    393
    Location:
    Santa Clara, CA
    Oops,

    I think you misunderstood what I was referring to as absurd! I am 100% for sprinklers and think in agreement with you on that. After re-reading my post, I see why the confusion...

    Anyway, the absurd part to me is that the code (NFPA 13D, if I remember correctly) says that you must have sufficient water flow to operate two heads simultaneously. If you can't meet that requirement, you are not allowed to install any sprinklers!? That is what I define as absurd. Even though the statistics are 95% in your favor of the system doing its job in case of fire.

    I was told once "break that connection to the sprinklers as your cannot connect an otherwise fine sprinkler system with your puny 5/8 utility meter". I turned the shutoff valve and disconnected a union. The guy signed off the permit and walked away. I had it hooked back up before he reached his car. Apparently, even inspectors shake there head at that one...
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