Removal of old ceiling boxes

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jeff48356

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Livonia, Michigan
Some ceiling fixture boxes in old houses are mounted using a thick metal bar spanning two joists, with the box attached to it. Let's say, for example, the box needs to be removed in order to install a ceiling fan in a bedroom (replace it with a ceiling fan box with brace). If working from above in the attic, what is the best tool to use for cutting the metal bar right along the joists so that the new box & brace will be able to screw to them flush? Would a Multi-Max tool with a metal-cutting blade do the trick?
 
If you're in the attic why not just pry it loose if it's nailed?

If you can't pry it loose, I would use either a saws-all with a (short) metal cutting blade or a Dremel tool with a large fiberglass cutting wheel.
 
Little Bill said:
If you're in the attic why not just pry it loose if it's nailed?
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Because these bars are placed on the bottom of the joists with drywall (or plaster) over them, so part of the bar on either side is not accessible. I don't want to use a sawzall and possibly damage the ceiling. In the past, I've used a plug-in electric drill with an attachment for a 7-inch cutting wheel, but I was hoping for something battery-powered. (besides, I can't seem to locate that attachment I used to have.)
 
I love my oscillating multi-tool for certain things. Cutting metal is not one of them. The blades are $15-20 each and you will burn up a brand new one just doing one bracket. I would not feel comfortable throwing a bazillion sparks in an attic with a grinder. I think a reciprocating saw (sawzall) is your best choice. Or some very hefty metal snips.
 
jeff48356 said:
Because these bars are placed on the bottom of the joists with drywall (or plaster) over them, so part of the bar on either side is not accessible. I don't want to use a sawzall and possibly damage the ceiling. In the past, I've used a plug-in electric drill with an attachment for a 7-inch cutting wheel, but I was hoping for something battery-powered. (besides, I can't seem to locate that attachment I used to have.)
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I used the word "Dremel" but I mean any brand of the same type. I have a battery powered Milwaukee and cut lots of metal with it. The cut-off wheel/discs are cheap and most of the time I get several cuts out of a single disc.

I didn't realize you were talking about the bars being attached to the bottom, so you will have to be careful not to cut through the ceiling. It shouldn't be a problem if you take your time with the multi- tool/Dremel.
 
Little Bill said:
If you're in the attic why not just pry it loose if it's nailed?
Click to expand...

jeff48356 said:
Because these bars are placed on the bottom of the joists with drywall (or plaster) over them, so part of the bar on either side is not accessible.
Click to expand...

If we are talking about those old time metal boxes with a very heavy gauge metal bar(normally black in color) their is a way to pry them loose. You have to cut the brace in the middle and use a small pry-bar. The problem is they often used a 16 penny nail all the way through the joist and sometime they even bend the nail at the end.

I don't think there is even a nail hole in the part of the brace that fits under the joist. The brace should slide out.
 
If the brace is actually nailed to the bottom of the joist, I think I'd cut the brace just anywhere, bend it out of the way, and install a 2x4 block(s) to support the new fan.
 
That style old box is really a pain. I've gotten frustrated a few times and damaged the ceiling. If I remember right when it comes out from the joist it offsets up. If you cut it on the offset the new box might go over it.
 
I also hate that type of bar.

It was nailed to the bottom of the joists, and offset to allow for the depth of the box minus the ceiling thickness. I usually cut the bar in the middle with a recip saw, through the ceiling hole, then push the two halves sideways in opposite directions, so they pivot on the nails, making room for the new box bar, which may have to be angled slightly to clear the vertical parts of the old bar. If you push upwards, the tips of the bar break through the ceiling.

But, I can do this without entering the attic.
 
GerryB said:
That style old box is really a pain. I've gotten frustrated a few times and damaged the ceiling. If I remember right when it comes out from the joist it offsets up. If you cut it on the offset the new box might go over it.
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That's an idea for a design improvement on the new fan brace boxes.. they should have a rectangular knockout that can be removed on both of the feet of the brace, and it would fit over the old metal bar fragments, allowing the feet to rest on top of the drywall to ensure that the box would be flush with the ceiling.
 
LarryFine said:
I also hate that type of bar.

It was nailed to the bottom of the joists, and offset to allow for the depth of the box minus the ceiling thickness. I usually cut the bar in the middle with a recip saw, through the ceiling hole, then push the two halves sideways in opposite directions, so they pivot on the nails, making room for the new box bar, which may have to be angled slightly to clear the vertical parts of the old bar. If you push upwards, the tips of the bar break through the ceiling.

But, I can do this without entering the attic.
Click to expand...

You'd still need to enter the attic in order to replace the existing 14/2 cable with 14/3.
 
That was my thinking.. sounds like this box is good enough to support fan. If you're unsure why not block off top with 2×4 and screw thru top of box for extra support?

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KnightPower said:
That was my thinking.. sounds like this box is good enough to support fan. If you're unsure why not block off top with 2×4 and screw thru top of box for extra support?

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It's not just keeping the box from falling out of the ceiling. Fan rated boxes have heavier screws and hubs for those screws to hold the fan to the box.
 
KnightPower said:
That was my thinking.. sounds like this box is good enough to support fan. If you're unsure why not block off top with 2×4 and screw thru top of box for extra support?

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Click to expand...

Or nail a 2 x 4 on each side of the box and use lag screws through the fan support. They are made so that you can secure outside the box
 
jeff48356 said:
Because these bars are placed on the bottom of the joists with drywall (or plaster) over them, so part of the bar on either side is not accessible. I don't want to use a sawzall and possibly damage the ceiling. In the past, I've used a plug-in electric drill with an attachment for a 7-inch cutting wheel, but I was hoping for something battery-powered. (besides, I can't seem to locate that attachment I used to have.)
Click to expand...

I have removed these in open attics by cutting them with bolt cutters close to the joist. If ceiling is already damaged, you could cut out around the bottom of the joist & pry the bracket out. All I've seen were nailed in with about a 10 penny nail.
 
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Coppersmith said:
It's not just keeping the box from falling out of the ceiling. Fan rated boxes have heavier screws and hubs for those screws to hold the fan to the box.
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If you support the fan from something other then the box - so what?

The rules for fan support focuses too much on the rating of the box, what that box mounts to and how or an independent support method is just as important.
 
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