plumbing leak in slab...

RatLabGuy

RatLabGuy

You look like a monkey and smell like one too
Joined
May 18, 2005
Location
Churchville, MD
Ugh. So, have a potential PITA plumbing issue.
Our laundry room and far bathroom are on a 4" raised cement slab that is on the back end of the garage slab, connected to the side of the house.
Somewhere inside this slab, there is a water leak I can't get to. All I know is that there are water lines I can see from the basement that go through the rim joist into the slab. There is laundry and a toilet on the exterior wall, and a sink on an opposite interior wall but the supplies to it come up from the floor, not in the wall.
So, at some point in the floor they must split. All I know is that somewhere embedded in there the cold line is leaking. We didn't even know, I just noticed one day last fall that I could just barely hear water flowing, and if I jiggle the supply line to the sink it changes pitch... and the well pump was running a lot. Otherwise no signs of water. As far as I can tell water was just leaking under the slab. So, we just cut off the water unless we do laundry until I can fix it :D
Well now water has started appearing in the adjoining basement wall floor seem, so it's time to do something about this...

I assume the *right* way to fix this is to bust up the damn slab, but I don't even know where it is. What a pain.
But I wonder - is there any reason I couldn't just cut off and abandon the existing lines, and instead re-route new ones to the fixtures? That will be a pain too, b/c I'll have to go from a source in the basement all the way up into the attic and across, then down into an exterior wall. But even that seems like less work.
 
Maybe you could run the new line out of the basement and around to the exterior wall in a trench underground? would that be easier?
 
This is why I will never own a slab house. I know a lot of people that have them.... I've been on to many job sites pouring concrete and seen the abuse the lines get and then just get covered up.

Sounds to me like your laundry was an add on to the existing house? The water is probably going between the slab and your basement wall where it just drained away.
On the outside can you see any separation of the slab from the house? That may have been what started it.
Like said above, you could probably figure out a way of just rerouting some pex instead of tearing out the slab. That would be my choice.
 
I wouldn't use any of the existing line, hot or cold.

Can you make lemonade out of this deal somehow? I mean, you can easily bust up the slab, run new pipes, and repour. It's work, but it's not complicated. Pipes in the attic will freeze. Pipes in exterior walls will freeze. Pipes outside have to be probably 18-24" down, and then you still have to figure out how to get them to the fixtures without going through the walls or attic or cutting open the floor.

So it comes back to the question: you have to do something. How can you get a net benefit above and beyond pipes that don't leak?

Also, I assume there's a waste line or three under that slab. If they're bell end cast iron, I'd consider replacing them as well.
 
If you've got a leak.....you've got potentially more than just a moisture problem. I've seen slab leaks lead to sinkholes. Especially in a garage area (heavier liveload, and point load from tire)

That shit from the 90's (polybutylene QEST "quest") is nothing but a soaker system when concealed. I have no idea what you may have as existing piping.

Cup/cap/abandon in place is the cheapest route. Followed by pex couplers routed up and over then down in the walls. Easy to fish it, and if you're good, you can really snake pex into places with a little creativity that keeps you from having to use a fitting (weak point in a pex system)

I never approve or spec pex in ANY application (other than residential repair) but it has it's place. This is one of them. Like Shawn said, if you route it outside the building envelope (heated space) you'll need to insulate it, but if you're lucky you can bury it between rafters/studs under the insulation.

The next best option is sawcut the slab and hammer out the existing concrete. Floor cutters can be rented, or hell, you can hire a plumber to cut it. Figure $15 a linear foot for a cut...(as well as whatever it's going to cost to get a guy there....maybe $75-$100) This is the most expensive option, but you also get the added comfort of knowing what the underslab damage is/was.

You can also uncover your lines (hope you've got a strong back, or a Jose and maybe a hose B to help) and run new below slab (jointless soft copper, insulated) piping to ensure it's done right. I'm not concrete guy so I'm not sure how much the replacement concrete will run you. But this is the most comprehensive and expensive route.
 
Seen 2 fixes for slab on grade houses where the owners just ran new lines down the hallway and called it good. Quick, easy, cheap and 100% effective...
 
You can do all that concrete work yourself, though. It's messy, but a circular saw with an abrasive blade can score it down an inch or so, then sledge to bust out the pieces. You can put it all back with $4 bags of quickcrete.

I have a Milwaukee saw that's about 15 years old. It's probably cut more brick, block, and concrete than wood.

But seriously, if you ever thought "it would be nice to have a shower in here" or "I wish we had one of those cutsey little mud rooms with the cubholes for kid shit" or "why in the fawk did they put the washer and dryer behind the door?", now's the time to do something about it.
 
Is the laundry room "nice" or just a utility room? Maybe you could build up a chase to hide the lines?

Had a similar problem at friend place in a finished basement. Added a line of built in cabinets, ran the line in the kick space.
 
Haha, thanks.

Some tidbits:
This is a late 60's Ranch house. I would NEVER buy a house w/ a slab foundation for this same reason. This is the only place it's an issue, all other water lines are easily accessible from the basement. It never occurred to me maybe this part was framed in later - basically the garage slab is the width of the house and they framed in the back 6-ish feet, but it's raised up higher... now that I think of it my neighbors' houses have full-depth garages and the laundry in the garage or basement.
But the guy (OP) that owned the house and his brother were builders, and made most of the houses in the neighborhood, then made his so it has a lot of unusual features for a 60s ranch, like a full walk-up staircase to the attic. And it's a little bigger than all the neighbors ;-).
Best I can tell the pipes in there are copper. Maybe this was framed in later, who knows.
No way to avoid the laundry and toilet supply being in the exterior wall b/c that's where the gas supply and dryer vent are.
Grey water line to septic is kind of strange too - instead of running all the way back to the main stack outlet in the basement, which is 3/4 of the way down the length of the house from here - on this end of the house, from the kitchen and what is in this slab apparently goes the other way out to a second line going out to the septic. So the grey water lines in this slab part are totally invisible to me.

Being a 60s ranch, the original attic insulation is terrible, R13, and I've rolled another R30 over it over the joists. The attic (sadly) doesn't get that cold. So the good news there is that if I ran up through the attic and kept it close to the floor I could keep it insulated between or under the R30 rolls.
Didn't think about Pex, I've always used CPVC.
House exterior is brick. No way I'm going through that.

Yeah I'm a little worried about where the water has been going and what's been vanishing under there. Last fall one day I noticed that the bricks down low on the back of the house looked wet, at first I thought it was from the outside faucet leaking but it was in a strange place. Since then I think now that water may have been leeching out and through capillary action maybe the bricks were absorbing it?

Shawn I here ya. If I do re-route the pipes I at least see this as a chance to add a sink to the garage on the other side of that wall. Getting the waste line connected will be interesting though.
 
kaiser715 said:
Is the laundry room "nice" or just a utility room? Maybe you could build up a chase to hide the lines?

Had a similar problem at friend place in a finished basement. Added a line of built in cabinets, ran the line in the kick space.
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I don't have any way to get to it from a source underneath. The rim joist in the basement is flat against the slab. And where they connect is the kitchen floor and open doorway to step from the kitchen to the slab, so I can't go up and over. Plus there's an exterior door going out back right between that entry and the laundry so I can't cover up the pathway.
Only option is repair, or complete rerouting up through some interior wall into the attic, over, and back down.
 
Now that I think of it - a joint in the attic is inevitable b/c I have to split it to go to the sink in the bathroom, and exterior wall for the laundry. Damnit.
Unless I did something weird like route down to the laundry, then put the joint there (turns out there's an access panel to the wall there so that's easy) then back up through the wall and over to the sink.
 
Jeff B said:
Why?
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Just because our projects are schools, colleges, churches, banks, library's hi-rise etc...commercial applications that usually require a 50+yr life expectancy. Standard spec is:

Hard Copper Tube: ASTM B 88, Types L, water tube, drawn temper.
Soft Copper Tube: ASTM B 88, Types K, water tube, annealed temper.

We don't allow T-drill, or mechanical connections either.

Wrought‑Copper, Solder‑Joint Pressure Fittings: ASME B16.22
Solder, brazing, and welding filler metals are specified in Division 15 Section "Basic Mechanical Materials and Methods."

And we absolutely won't allow CPVC supply piping for any kind of commercial, or multi-residential....even if hired by a contractor for design build. WAY too many failures associated with CPVC supply piping (even the FlowGuard Gold®...saw LOTS of failure on that at Pennybyrn At Maryfield in Jamestown).

Now, having said all THAT, maintenance departments will repair facilities all day long with pex, CPVC, t-drill, and mechanical coupling methods (because they're cheap) and swear by their repairs, but there's too much liability associated for us to stick our necks out on anything but standard copper on commercial. And it's not the product to be brutally honest, it's the fittings and how they're installed. If a helper mocks up a copper runout, and forgets to solder a joint, the second the system goes under pressure the failure is found. In a pex application, the fitting and the clamp can provide enough initial strength to hide for a while if it's not properly torqued. Maybe even long enough to have building operation cycle a time or 2, but once there's movement (water hammer) it starts coming undone. And then there's the sheetrock screw factor, and trying to protect pex/cpvc.
 
Nothing to add to help OP, but I will add that I cannot wait to get ALL the copper out of my house and install new pex! 25 year old house and leak after leak and none of them are at a joint. Just a pinhole in a straight section.
 
RatLabGuy said:
Now that I think of it - a joint in the attic is inevitable
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That's NOT the end of the world. A joint will be your most likely source of a failure. But if you've cut the pipe square, installed the fitting correctly and properly clamped the ring, you shouldn't have a problem.
 
89wrangler said:
I cannot wait to get ALL the copper out of my house and install new pex! 25 year old house and leak after leak and none of them are at a joint. Just a pinhole in a straight section.
Click to expand...

I would venture to say that you have 2 possible culprits. (just speculation)

You may have an unusually low PH (high acid), which doesn't allow scaling of the insides of your pipes (quite the opposite of many municipal water systems trying to RAISE the scale level of piping to coat old primary water lines to keep them from failing...I.E. the more scale, the thicker the wall of the pipes and less likelihood they have to replace them due to failure)

And/or you have a high pressure/velocity issue (well pump too high or PRV not functioning properly) which Pex fittings will reveal as well.
 
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I own two houses all copper no issues. My old one was installed in 1954 (according to the newspaper insulation) and all good.

X2 against pex for it just seems sketchy to me... What happens in 20-30 years when the little metal clips rust and fail? Anything that contains water will swell and contract along with plenty of condensation.

I for one am preparing the best I can to not be either under, nor on top of a house after I turn 75... But for this instance sounds like pex may very well be the only way to go?
 
RatLabGuy said:
Now that I think of it - a joint in the attic is inevitable b/c I have to split it to go to the sink in the bathroom
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Home run it. Put two pex manifolds in the basement and home run the supplies from each fixture back to the manifold. Pex pipe is close enough to free not to matter.

6BangBronk said:
What happens in 20-30 years when the little metal clips rust and fail?
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They're usually copper, and they're not exposed to moisture. If they're not copper, they're pex.

Every 50 year old house in Raleigh that's on a well or used to be on a well is just about due for a whole new set of interior piping. It starts with the hot water pipe. Closest to the water heater will go first. After that it's around the washing machine attachment (water hammer), then anywhere there's a threaded connection. Once those all get repaired with new pipe, it starts somewhere midway through the pipe runs.
 
OK so pretend I go the new lines route.
School me on why PEX over CPVC in the attic. I have done many CPVC fittings and feel OK about them. I like the "instant failure, or not at all" aspect.

My thinking is that to get the line from the basement up there, I am going to have to pick an ideal interior wall (that doesn't have an elec. line in the way) and drill holes in the top and bottom wall plates, VERY CAREFULLY measured so they line up, and fish it up there from the bottom up, hitting the top hole ninja-style. I've done this before with conduit for electrical. I think I dropped a line w/ a weight down the top hole until it fell through the bottom, then used the wire to guide the pipe up to meet the top hole.
Hard to see how that would work with PEX - I'd have to first fish a rigid pipe or conduit, then use that to chase it.
If I have to use that rigid pipe anyway why not just use CPVC?
 
shawn said:
Home run it. Put two pex manifolds in the basement and home run the supplies from each fixture back to the manifold. Pex pipe is close enough to free not to matter.
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I have a manabloc manifold sitting around waiting for that project in our house. Might move the water heater too. Home run setups really make sense for many reasons.
 
shawn said:
Every 50 year old house in Raleigh that's on a well or used to be on a well is just about due for a whole new set of interior piping. It starts with the hot water pipe. Closest to the water heater will go first. After that it's around the washing machine attachment (water hammer), then anywhere there's a threaded connection. Once those all get repaired with new pipe, it starts somewhere midway through the pipe runs.
Click to expand...

That's when I will have no choice but to hop on board with pex for I'm sure mine will wait to go bad when copper prices are through the roof...

But I still have a mental taste of plastic when I drink from pex. Like every water dispenser from every fridge I ever tasted. But then again, I'm so particular of my water that I buy mine by the 5 gallon jug and only way I disperse is from a crock.
 
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