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Old 06-08-2019, 11:06 AM   #1
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Question Conduits Exiting Cast Concrete Walls

We just started a project with a ton of cast concrete walls.



In most situations there would be no problems, we would drill a hole in the forms just big enough for our conduits to fit through and then the GC would pour the concrete around the pipes. However the GC has just informed us that we are not allowed to pass any conduits through their forms. So now we are scrambling a little to find a solution.



Per the job spec we can only use RPVC piping. The walls in question are 8" thick, and a 3/4" RPVC 90 is 7", but I'm a little nervous to tape the end up and hope that it doesn't move when they pour. Even with sufficient tie wire that's just begging for a pipe to fill with concrete or be pushed away from the edge of the wall to never be seen again. And even though the 7" leaves enough coverage to pass spec having the back of the 90 1" away from the outer edge of the cast make me nervous that somewhere down the line some one will drill a hole for a concrete anchor and hit these pipes.



Any ideas?
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Old 06-08-2019, 11:54 AM   #2
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Sounds like GC (or concrete subcontractor) needs to provide you with sleeves of the proper size in the proper location.
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Old 06-08-2019, 12:09 PM   #3
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Can you set a box facing the form? Inside the form facing out. Pull it up tight with tie wire and tape box and connectors well?
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Old 06-08-2019, 12:51 PM   #4
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Google conduit stub downs or conduit slab inserts.


These are made with a tighter radius and a flange for securing them to a concrete form.
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Old 06-08-2019, 01:38 PM   #5
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Quote:
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Can you set a box facing the form? Inside the form facing out. Pull it up tight with tie wire and tape box and connectors well?



Unfortunately not, there will be inaccessible drywall ceiling located all around the stair wells, and due to the nature of the building an access hatch is out of the question.


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Google conduit stub downs or conduit slab inserts.


These are made with a tighter radius and a flange for securing them to a concrete form.



I'm going to have to look into that. As I mentioned to John Valdes im up against inaccessible dry wall ceilings so I need to be very careful about my bends. How are those to pull through? They look really tight.....
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Old 06-09-2019, 08:35 PM   #6
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Offer up an apprentice to drill an oversized piece of plywood with your conduits through it to attach to their forms? Split the plywood horizontally, so that it comes off in two pieces once the GC is ready to strip the forms. If you can get the GC to cut out a rectangle in the forms, then you can use that piece behind your oversized piece to keep the wall flush all the way up.
At least that way, the GC won't have to be messing around with all of your conduit penetrations, and they may look at it that you are at least will to work with them.
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Old 06-09-2019, 11:11 PM   #7
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Can you screw/nail a round concrete box to the back of the form. Before you attach it take out a 3/4" KO out of the back. Slide 90 in and tape up the end. Either pack the box with newspaper before you attach it to the form, or fill it with spray foam after. Then tie the conduit down good. The void left by the box would be perfect to change over to EMT later. You can patch the hole later if necessary, but if it is above a ceiling I wouldn't bother.


We did a mostly precast prison years ago. All the conduits and boxes had to be laid out ahead of time for the precast company to install. In places where the conduit had to run horizontal between panels, not often, they would stub the conduit into Styrofoam towards the face of the form. later the conduits were connected with Carflex and the concrete patched. maybe you can do something like that? Then you wouldn't need a 90. Put the 90 on later.
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Old 06-10-2019, 09:00 AM   #8
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I've been doing this for 20 years all our pipes are in concrete. There's a couple of ways to skin a cat. This room is a floating slab so we can't go directly into the equipment.

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Old 06-10-2019, 03:06 PM   #9
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Can you screw/nail a round concrete box to the back of the form. Before you attach it take out a 3/4" KO out of the back. Slide 90 in and tape up the end. Either pack the box with newspaper before you attach it to the form, or fill it with spray foam after. Then tie the conduit down good. The void left by the box would be perfect to change over to EMT later. You can patch the hole later if necessary, but if it is above a ceiling I wouldn't bother.


We did a mostly precast prison years ago. All the conduits and boxes had to be laid out ahead of time for the precast company to install. In places where the conduit had to run horizontal between panels, not often, they would stub the conduit into Styrofoam towards the face of the form. later the conduits were connected with Carflex and the concrete patched. maybe you can do something like that? Then you wouldn't need a 90. Put the 90 on later.

We're in the same boat, precast prison. Im going to look into boxes, not a bad idea. The ones we have on site right now are the deep boxes, same idea more infill I guess.



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I've been doing this for 20 years all our pipes are in concrete. There's a couple of ways to skin a cat. This room is a floating slab so we can't go directly into the equipment.

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That looks amazing, Heavyritefoot, what did you pack around the pipe to get such tight holes to your pipe?
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Old 06-10-2019, 07:29 PM   #10
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Quote:
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We're in the same boat, precast prison. Im going to look into boxes, not a bad idea. The ones we have on site right now are the deep boxes, same idea more infill I guess.
In our situation we had to review each panel being supplied by the precast company. We had to detail what we needed in each panel. We had Power, Light, Phone/Data, Security, Everything.... Once detailed the precast company put in the conduit and boxes off site and the panels were brought in from out of state.



The only thing we didn't have to detail was the actual jail cell. They already had their modular detail. They were built complete. Plumbing and electrical fixtures were already installed. Even the bunks. Then they were stacked six stories tall. Two wings. Two cells put together formed a small triangular chase between them. We connected the risers in the chase. All the way down, across the slab/basement and back up to their respective floors security and electrical rooms. Very few drop/security ceilings.



Many drops were done with regular tile boxes mounted flush to the back of the form. Later Raco #187 extension boxes were installed, and then piped to.


You may be able to make your own sleeve out of EMT using Caddy 740 pipe positioning clips instead of using round boxes?



I would like to know what type of sleeve Heavyritefoot used? were they Arlington CPS sleeves?
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Old 06-10-2019, 10:03 PM   #11
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Ipex makes a lot of items for concrete. Precast is made off site....they put the boxes in for us. What your talking about is form work it's a 200mm thick wall then they laminate 13mm drywall right on it or some walls they furr out a bit. For those pipes I used a blue jay, come or hat. There's three different names for the same item. I'll get a picture of a coke for you tomorrow morning when I'm at work...That's what I would use what your describing for your work...........Here's a picture of the top of the mechanical penthouse 45 floor. Lots of pipe.

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