Cast iron drain – concrete slab: Options
I’ve searched the forum but I just can’t seem to find and answer as to how to break/cut the concrete slab without breaking the cast iron drain.
I hope you can help me.
I am planning on building a bathroom in my basement which requires me to cut the slab and tee into the main stack (cast iron) which is actually in a corner of the room, about 1 ft from each wall.
My plan is to either rent one of those big concrete saws or use my angle grinder with a diamond blade and a chisel to cut the slab and then cut the stack and use a PVC Y with rubber sleeves to connect everything back together.
Four questions:
1) What is the best (and cheapest) way to cut the slab and the cast iron pipe?
2) How to I cut/break the slab without any damage to the cast iron pipe?
3) How do I determine which way the drain is pointing under the slab before cutting it? The basement floor drain is right in the middle of the room, the stack is between the basement floor drain and the front of the house.
4) When pouring back fill concrete, do I need to wrap the pipe that comes out of the concrete in some sort of insulation to prevent the concrete from constricting it?
If you have any other recommendations please feel free to share them here.
Thanks
Replies
Except for the drain it'self all of the piping is under the slab.
I would get an electric demo hammer to break out the concrete.
You can use the grinder/saw to cut around the drain to isolate it.
AFTER you break up the floor you will have to dig down to get to the pipe.
I would rent a CI snap cutter to cut it.
And you probably will need to take out a section and use 2 'straight' couplers to patch in a PVC Y.
Most floor drains have real sharp trap that can be snaked. So on the side they have screw plug that when removed gives you access to the drain pipe past the trap.
So that is the direction of the drain run.
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A-holes. Hey every group has to have one. And I have been elected to be the one. I should make that my tagline.
First off I am not a Plumber but I will give a bit of info.
1) What is the best (and cheapest) way to cut the slab and the cast iron pipe?
Best way Diamond saw with a water feed cooling system (in a inclosed basement a Elec. is better then a gas powered demo saw since it is hard to vent out the exhaust.
Other way is a Diamond blade in a worm-drive saw and a bucket of water to keep a puddle of water to keep the blade cool as the water turns to a slury clean it up and start again with fresh clean puddle of water.
2) How to I cut/break the slab without any damage to the cast iron pipe?
See above you need to cut the concrete then carefully break it away without sledging on the pipe.
3) How do I determine which way the drain is pointing under the slab before cutting it? The basement floor drain is right in the middle of the room, the stack is between the basement floor drain and the front of the house.
Your floor drian may or may not even be tied to the sewer line. If it is it will have some way to keep it's trap full of water to prevent sewer gases from entering the basement.
In some older houses a whole house trap might be installed and this would keep sewer gases from entering trough the floor drain these were installed in houses plumbed before traps were installed at each fixture as they are now. if you have one of these it would be near a cleanout.
Also in areas that have storm water and sewer drains combined you can get sewer back flow so some type of back flow perventer will be in installed (ussally sewer back flows effect below grade drains but unless is is a major back flow it will not flood above grade fixtures. But a basement bath could have back flow.
Also the floor drain could be just be tied to a sump hole and interior curtain drain system and not even be conected to the sewer drain and stack.
As for which way the pipe runs without being there I could not say but you can find castiron pipe under a slab using a metal detector.a
4) When pouring back fill concrete, do I need to wrap the pipe that comes out of the concrete in some sort of insulation to prevent the concrete from constricting it?
NO
Pretty good answers for not being a plumber. ;-)
Except #4 while the concrete does not "constrict" the pipe it does need to be protected from the concrete.
Every code that I know of requires some sort of wrap to protect the pipe from concrete, except radiant heating tube, they can be laid directly in the slab.
“The world is a dangerous place, not because of those who do evil, but because of those who look on and do nothing.” —Albert Einstein
1. best is a concrete saw, cheapest is a sledge hammer.
2. Start away from the stack & punch a hole in the slab so you can undermine the concrete around the stack.
3. Sewer or septic? If sewer look for the manhole covers, generally the stack turns directly for that path to the sewers.
4. Yes, Rubitex¯ black foam rubber pipe insulation is perfect for that & cheap.
“The world is a dangerous place, not because of those who do evil, but because of those who look on and do nothing.” —Albert Einstein
I like to dbl wrap pipes with 5.5" sill seal foam... cheap, easy and always the correct size.A La Carte Government funding... the real democracy.
Been there, done that.
Sledgehammer. Big one. And someone with the kahunas to swing it. You'll be amazed how fast it goes. In fact, the time it took to type your post is how long it would take.
The sledge will throw some ceement chips and pieces of stone. Where good safety glasses.
Oh, the saw will be fast, but what a mess! The wet mud from a wet saw will plaster everything. Probably need muratic acid to clean it up. Try it dry and the dust will overwhelm you within seconds, not to mention the cleaning up of the ENTIRE house. You can build tents and bring in dust evacuators, but you're running up the bill. Cleaning up after the saw would take 10 times the amount of time the sledge method. And I love running my ceement saws! Gots lots of them. They're my friends.
The saw will leave smooth edges. The sledge will leave jagged. Which do you think will offer a better surface for your new ceement to grip to?
Those are great answers, thank you all for taking the time to post them.
Now I know what I need to do.
BTW, it's a sewer system so I need to keep that in mind.
The lastes FHB issue (April/May no. 194) has a nice trick on how to deal with dust, basically you cut a big water plastic jug lengthwise (the water cooler type) so you have a slopped base, cut a whole for your hand and shopvac hose and use it as a "cover" for your saw/angle grinder.
Thanks again.
Just last week....
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50 year old 4" concrete with river rock, clay from the devil's kiln and a cast/pvc connection at the sewer that couldn't be planned any worse.
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12" diamond saw (electric and waterless), 6 passes and still some to go, 16# hammer. The cast iron never cracked... 'til I meant to break it.
You may oughta plan on replacing the cast with pvc all the way to the sewer if it's pvc. What the hey, you're plumbing anyway. No better time than now to make it last for the duration.A La Carte Government funding... the real democracy.
Let's be real.
Your ceement floor is 4" thick? A 14" diamond blade cutoof saw will go 5.5". That's what you're gonna need.
Describe how that gas powered 14" saw will fit inside of one of those "dust collectors." And what type of vacuum will be necessary to keep your work area clean from that beast?
Good work Hackinatit, I hope I can achieve similar results. It will take me 1 million years but I'll get there.
Ehhh, dust.... ehhh, overrated, hehe.
I'm sure I'll come up with something to cut the slab, most of the time I try to work smart not hard, if one approach is not good I'll go to plan B.
I'll try to post some pictures once I start the work so you can see my progress (and mistakes).