Can I "sneak" pipe under a slab?

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Old 10-12-12, 10:22 PM
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Can I "sneak" pipe under a slab?

I'm often impressed with the ingenious and simple tricks people have used through the years to get past a hurdle in a project. I'm hoping there is one for my situation. I need to run supply and drain pipe from a crawlspace to a planned laundry tub in an addition on slab. The slab is only 9 feet across. Is there a trick to feeding the lines under the slab to come up through a hole drilled with a rental drill?

The earth in this location is all sand.
 
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Old 10-13-12, 01:43 AM
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I've seen pipes installed under a slab, end to end, but to come up thru a hole in the slab is going to be tricky.
 
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Old 10-13-12, 01:50 AM
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The easiest and probably least expensive way to accomplish what you want, believe it or not, is to saw an opening/path in the slab and then repair it with concrete when you are done.
 
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Old 10-13-12, 08:33 AM
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The easiest and probably least expensive way to accomplish what you want, believe it or not, is to saw an opening/path in the slab and then repair it with concrete when you are done.
This is my fallback plan if there's no "redneck" method of feeding pipe underneath. Seems like someone might have tried an ice spud, repeatedly jam in a pipe & empty, shopvac...I wouldn't even consider this if I thought I'd hit rock, clay, roots, etc but everywhere I dig in that lakeside community I only hit light dirt & sand.

Just to "git er dun" I normally would rent a saw & then clean up the big mess but it's a 2-hour round trip to the nearest rental.

 
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Old 10-13-12, 09:18 AM
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I know you want to break the slab but did yo check your pitch?

I see you are tieing to the toilet line somehow. You may not meet where you need to. Remember 1/4" per ft.

It would seem the main line would exit where I show. You can always trench outside. Blue is vent.

As far as water lines there is no reason you cannot go up in the attic. Run it under the insulation. The heat from the room keeps it from freezing. I have never had an issue and we
re-pipe homes on slabs like that 98% of the time.


But do what you need.


To run under the slab you would need a bullet mole.


BulletMoleŽ: The fastest, easiest, cost effective, way to install irrigation pipe or electrical conduit under sidewalks, driveways, and other hardscapes





 
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Old 10-13-12, 10:16 AM
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lawrosa.....that Bullet Mole is incredible. It's amazing the way it broke thru that boulder.
 
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Old 10-14-12, 08:02 AM
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Bullet Mole looks like it would work. For what I have in mind probably so would any hand-driven well pipe setup. I could hand-drive a galvanized drain pipe horizontally. ( or 2--the second one to sleeve the supply lines)

lawrosa your suggestion opens a slew of new questions.
Why would I want to run the drain outside where it would need to be below the frost line? That's a LOT more digging than the 3" drop needed to pitch the drain under the slab. Plus if I start at the frost line where your drainline would exit the house and drop 1/4" per foot as it runs around the foundation, am I not going to end up several inches below where the main drain exits the house on its way to the septic tank? Wouldn't that be a show-stopper?

Currently the toilet, sink & shower drains all drop straight down through the ~4 foot space in the crawl and vanish into the dirt. They must connect together somewhere under the surface. In any case there are 3 pipes to choose from for my tap.


Am I being dense and missing something obvious here? The supply lines and the drain lines are 12' away from the laundry tub location, in a straight line, through a crawl space to which I have access via a hatch in the new basement.
This cottage is a gut renovation & I've laid out my floor plan to put all the supply & drains in a straight line along the same side of the house as the septic tank. IMO all this "back story" is unnecessary to the question here.
 
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Old 10-14-12, 08:36 AM
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Why would I want to run the drain outside where it would need to be below the frost line?


If your toilet exits where I show, I doubt it will be 4ft down. But you never know. A good way to tell is how deep is the septic?

My line is 21" below grade.... Yours?

Usually its water lines that are buried that deep.
am I not going to end up several inches below where the main drain exits the house on its way to the septic tank? Wouldn't that be a show-stopper?


You only need to go as deep as the line is outside. Again what height is your septic?


Currently the toilet, sink & shower drains all drop straight down through the ~4 foot space in the crawl and vanish into the dirt. They must connect together somewhere under the surface. In any case there are 3 pipes to choose from for my tap.
Thats Odd..... That would mean your septic is at least 6 ft under ground to the top of the septic??? That would mean they dug a 15 ft deep hole to install the septic?...

Never seen it.....but if you say so...

IMO all this "back story" is unnecessary to the question here.

Yes then.... Start hammering, cutting or what ever you need to make it work.


To answer your original question,

I would run the two 1/2 pex lines in a piece of 1 1/2" pvc next to the drain line you put in the slab. This way its sleeved the entire length.

You will need a long sweep to come out of the slab so the pex does not kink.

If you do not do that and a leak develops you would need to break up the cement to repair.

Vent the drain line accordingly. And yes 3" drop @12ft.


Good luck. Let us know how it works out.













 
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Old 10-14-12, 11:43 AM
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You're making some implausible and very exaggerated assumptions about my setup. Is this to make me look uninformed? The frost line in Michigan is 42-48 inches. The TOP of my tank is about 3 feet below ground and is located by the rear of the house on a sloped lot. I have no idea why you would say my tank top would be buried 2 feet below the frost line...this makes no sense to me as the inlet should be a few inches below the top--not above it. You seem to be getting your wild depth numbers from my statement that the pipes drop down about 4 feet into the dirt. My floor is of course above grade and some of that has been excavated for easy access to the plumbing & electrical. I thought all this describes a rather normal system.
 
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Old 10-14-12, 12:16 PM
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You're making some implausible and very exaggerated assumptions about my setup. Is this to make me look uninformed? The frost line in Michigan is 42-48 inches. The TOP of my tank is about 3 feet below ground and is located by the rear of the house on a sloped lot. I have no idea why you would say my tank top would be buried 2 feet below the frost line...this makes no sense to me as the inlet should be a few inches below the top--not above it
Oh I am so sorry you are somewhat offended. But I did not assume anything. I asked you a questions in post #8. Here is it again below.

If your toilet exits where I show, I doubt it will be 4ft down. But you never know. A good way to tell is how deep is the septic?


And here is another question I asked.


You only need to go as deep as the line is outside. Again what height is your septic?


And more questions marks. This is regarding pipes coming directly from fixture and down into the earth. In all my plumbing years I have never seen this.

Thats Odd..... That would mean your septic is at least 6 ft under ground to the top of the septic??? That would mean they dug a 15 ft deep hole to install the septic?...



My line is 21" below grade.... Yours?


In regards to your comment below, you asked for advice. If you do not like the advice and are angry at something, then possibly you would like to seek advice elsewhere.

I am only a volunteer here and offer my time for free. I felt I offered the best advice to you. I was merely trying to save you the trouble of cutting the slab.

implausible and very exaggerated assumptions











 
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