Prepping a slab for kitchen island

15505 Views 10 Replies 6 Participants Last post by Knucklez, May 2, 2009

tiger275

Discussion Starter · Apr 30, 2009

I bought an existing home where the slab was prepared with a sink drain stubbed off through the slab but the unfinished plans called for the water and electric to be brought to the location inside the walls. My wife has decided that she does not like the original plans and wants an island instead. I need to prepare for this prior to installing the flooring and cabinets. I have a concrete guy who will cut me a trench (all the way to the soil) in the concrete and refill with concrete when complete. I need to place water supply lines and an electrical conduit (PVC - to run electrical later) in the trench. Then we will backfill/top with sand and refill with concrete and smooth to match the existing floor. From the wall (with the supply lines and electrical junction) to the island is around 70". So I will be going down, across and then back up.
I have multiple questions.
1) Is there a way to put something in the floor now and run the water supply lines later (like a conduit)? If so, does that force me to run PEX later since I cant see a way to route the copper down and then back up?
2) The whole house is copper today so I think I prefer to use copper for this. Can I mix copper (to the slab) with PEX (under the slab) and back to copper (on the island side)? If so, why would this be a good idea or bad idea? I assume PEX under the slab would not have any junctions so reduce leak opportunities
3) If I run copper, is there any reason not to sleeve it in PVC to reduce contact to with the concrete and allow for movement/flex
4) If I run PEX, can I run it both Hot and Cold in the same "conduit"

Sorry for all the questions. I would love to hear some constructive ways to prep this space now for the future work of adding the sink and electrical to the island.

Ed

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Just Bill

· #2 · Apr 30, 2009

Hard(copper) lines could be run and stubbed for later connection. Not sure that PEX is OK for potable water supply, check local code for all of your questions. Codes vary all across the country.

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majakdragon

· #3 · Apr 30, 2009

On all the slab jobs I have worked on, soft copper is run for the water lines. This eliminates any joints. Personally, I would not mix materials in a line. The part of the copper that would come in contact with the concrete is covered with a plastic (soft) cover/sleeve in red (for hot) and blue (for cold). I agree in checking local code as far as what material to use. There may also be a certain distance required between plumbing and electric lines under the slab.

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al's sewer

· #4 · Apr 30, 2009 (Edited)

I would recommend using soft copper also and I would use at least l or k type as they are thicker and last longer. I do not recommend as mentioned above using different metal materials unless you use dyna electric unions in an area where they would be accessible. Do not use any joints under the concrete slap. I also recommend insulating your pipe with either armaflex or rubbertex pipe insulation to avoid have rocks vibrate against the pipe and causing leaks in the future. You can also use the insulation for a sleeve therefore eliminating the use of a plastic sleeve. But again check your local codes to see if that is acceptable. Also some areas do not permit running water and electric lines in the same ditch so you might want to check on that also.

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tiger275

Discussion Starter · #5 · May 1, 2009

follow up

Thanks everyone for the great feedback. I have an appointment with the local code guys tomorrow and here is what I am going to ask them (based on what I think I understand from above)....
Can I run two parallel PVC pipes (chases) from the wall (maybe 6" up), down through the concrete, across the ground (to be buried in the repaired channel) and back up through the concrete into the island? The purpose of these two channels would be to allow me to come back at a later time and use 1 to fish electrical to the island and use the other to pass soft copper through from the wall to the island.

Does this sound like what you are all suggesting as the best coarse? It would allow me to repair in the future should I get a leak by simply running a new soft line and it would keep the electrical and water in seperate pipes.

Can I run two water lines in the same PVC sleeve? If so, what size copper and what size PVC would you suggest? I am thinking 2" or at least 1.5" with sweep 90s to help fish the pipe and electrical through later.

Thanks again for the great feedback and any additional advice you can offer.
Ed

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JDC

· #6 · May 1, 2009

You CAN run pvc conduits for pulling PEX later. I've had to do this numerous times for soda fountains and the like. The thing is that pulling the PEX can be a bit of a PIA. In addition, if the floor is going to be opened up anyway, why wait to put your lines in? You can go from copper to PEX to copper with the proper connections, but again....if the floor is open, why? I'd use type L soft copper, insulate it with foam rubber pipe insulation (not the cheapy crap they have at the box store..go to a supply house and specify foam rubber Armaflex). After that BURY it so that there is no contact with the new concrete. Be sure to tape up the ends so you dont get debris in the tubing during installation. Just stub the ends up in the wall and at the island. The tie in can be done later.

Good luck

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majakdragon

· #7 · May 1, 2009

I agree with JDC that fishing any type of piping through a sleeve will be difficult and would place the soft copper in the trench while it is open. The only thing I cannot tell you is how far apart electrical must be from plumbing lines. Please let us know what the inspector says.

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tiger275

Discussion Starter · #8 · May 2, 2009

Final answer

Well, thanks to everyone for the replies. Here is what the code guys in Loudon county TN said....
Run the flex copper (L) through and under the concrete (wrapped in armaflex or similar where it will touch the concrete). Make sure it is buried in sand or similar so that it does not contact the concrete under the slab (or wrap the entire run in insulation/armaflex). It is ok to run the electrical in the same trench. Just make sure they do not contact. They prefer the electrical in conduit.
So you guys were spot on.

Thanks

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majakdragon

· #9 · May 2, 2009

Glad it will work for you. Thanks for letting us know what the inspector said.

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al's sewer

· #10 · May 2, 2009

tiger275 said:
Well, thanks to everyone for the replies. Here is what the code guys in Loudon county TN said....
Run the flex copper (L) through and under the concrete (wrapped in armaflex or similar where it will touch the concrete). Make sure it is buried in sand or similar so that it does not contact the concrete under the slab (or wrap the entire run in insulation/armaflex). It is ok to run the electrical in the same trench. Just make sure they do not contact. They prefer the electrical in conduit.
So you guys were spot on.

Thanks

insulate the whole pipe for extra protection. I'm done

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Knucklez

· #11 · May 2, 2009

for the electrical that you mentioned.. make sure you put in some fairly strong string in the PVC so you have something to help guide a fishtape through it. nothing worse than finding out later that you can't thread a wire into the conduit!

Knucklez

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