I am installing some potlights and a dining room fixture (box) in my condo which is an older building - the ceiling is concrete-with wire mesh supported by rebar tied into 3" wide x 18" high steel joists. It is a very strong ceiling which has been smoothed and is in good repair.

I have cut the potlight holes without a problem - then measured for the dining room fixture and tested to be sure I wasn't under a steel joist - and then cut a hole to insert the box. Unfortunately - I found a solid 1/4"" rebar in the middle of my hole.

See:

My question is - can I just cut the re-bar (probably using either with a hack saw or a grinding wheel) OR should I avoid cutting it and move the hole over 2 inches? (which isn't as easy as it sounds).

Also - I intend to make a frame out of 1/2" plywood with 2 pieces 4" wide (to fit through the hole) and about 10-12" in length forming the 2 legs of an "H" then stack another piece of wood on top to complete the "H". Then I will screw the box into the center of the "H". (I can glue the pieces together - and add a few drywall screws from underneath to hold it).

Is this an acceptable way to secure the panel ? I am not planning to have a very heavy light fixture - maybe 10 - 15 lbs?

Thanks for your help

Robert

 

Not knowing how that re-bar is attached or used I think I'd would rather error on the side of safety and move the hole. Curious as to what the experts say.

 

Since you are just installing a fixture why not use a shallow pan box? You can install it directly to the rebar using some self taping screws.

 

Thanks for the suggestion about the shallow pan - I am currently googling them and that might be the best choice. But there is NO WAY to screw anything into this round 1/4" rebar IMO - its very hard. But I might be able to clamp something to it firmly and with a piece of wood above screw into it for added support.

 

A self tapping screw will go through the steel. That type of steel is not that hard. It some times takes a couple of screws, or predrilling a smaller hole to make it through, but it will.

Note the self drilling end on the screw:

[ATTACH=CONFIG]27592[/ATTACH]

 

OK I am willing to give it a shot and if it works GREAT !

 

Instead of using the self-tapping screws, you could drill right through the steel girder in a couple of places (you can drill through the shallow pan box if needed) and bolt it on.
NR

 

Thanks Kahuna - but how do you put a nut on the end of a fastener once the box is in the way?

 

Just use a U-bolt around the rebar. . Use the plate that comes with it to hold it to the rebar with the legs sticking out. Slide the pancake box over the legs and hold the box in place with two more nuts. If the regular nuts behind the box hold it out too much use speed nuts or just temporarily duct tape the you U-bolt.

 

This looks like plaster over metal lath and the lath is tied to 1/4" pencil rods.
I have run into this before. Usually I am there to repair the plaster after a water leak or when plumbers have been working above the plaster.
Do I see diamond mesh metal lath or rib lath around the edges of the hole.
Nice cut by the way. What did you use to make the hole?
You have plenty of suggestions on what to do.
Here is one more but first you need to see how your round rods are spaced.
Are they 12" apart or 16" ? How are the joists spaced? 3' or 4' or more or less? The closer everything is the safer it is to cut the rod.
My inclination would be to cut the rebar but be careful of vibration. If you cut it in such a way that you shake it up and down or back and fourth it could mess up the plaster.
If you want to move the fixture and close up this hole we can tell you how to do that. too. It is easy.

 

Taking suggestions from all, I would cut a slot to match the pencil rod in a 2x4, lay the 2x4 above the ceiling and screw my shallow box to the 2x4, which is now laying flat on your ceiling. No cutting of the pencil rod, no clamps, and the 2x4 will handle the weight of a light fixture, NOT A CEILING FAN, however.

 

I doubt if it is even necesary to cut a groove in the 2 x 4. The rod is probably well embedded in the plaster that pressed through the lath and would not be a bit surprised that the plaster is well above the rod. Stick a 2 x 4 as long as you can get through the hole, put some screws in it through the plaster 9but not all the way through, install the shallow box and install he lite. Fill the screw holes with some joint mu or spackle.

 

This bothers me. Especially coming from Chandler. That box won't be secured and would be free to shift around. That's not to code. And I'm sure would not pass inspection if found. If a fire were to occure do you think an insurance company would cover if this was found?

Move the hole and secure the box via 2 x 4 to the joist or other structual member.

 

I don't think the box will shift if the lumber is secured through the plaster and lath as tightcoat mentioned. The lumber can be drilled for the incoming cable and a shallow box secured to the lumber. I look at my post and find where I failed to mention the screws as did tightcoat. Do it a hundred times it's habit. Try to tell someone how to do it, you leave things out. Thanks for the catch. Moving the hole is an option, but it would require patching an ugly hole, and I am not sure how far apart the pencil rods are spaced. May hit another one trying to miss one

 

I would groove the piece of lumber id needed and mount the box to it. I wouldn't feel compelled to run any screws through the adjacent plaster.

Once that's all done and the ceiling is patched to the box, it's mot going to be able to move or shift, IMX.