Ceiling Box + Engineered Joists

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Topic by Jimi_C posted 09-09-2012 07:18 PM 12049 views 0 times favorited 9 replies Add to Favorites Watch
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9 posts in 3338 days

09-09-2012 07:18 PM

I’m trying to install a new ceiling box over my kitchen island, due to the fact that the old box was not flush with the ceiling surface (it was flush with the top of the drywall, so about 1/2” too deep). After pulling the old box out, I saw why – my home was built using engineered joists (I-joists). The builder apparently decided to mount the old hanger bracket slightly above the I-joists bottom flange, so that the brackets on the end were bowed out. The overall result being the box was too shallow.

The replacement hanger I bought is just barely clipping that flange (less than 1/4”), so I cannot expand it without slightly lifting it up. This of course presents issues of its own, since once tipped up a little the “feet” (plastic triangles attached to the bar) no longer make contact very well making it damn near impossible to continue opening up (the triangles have a tendency to tip over, since they’re not making good contact). Also, since the bar would be slightly higher, the box would no longer be flush with the ceiling, which was the original issue I was trying to fix.

I’ve read a few suggestions online regarding how to fix this, but I thought I’d ask here as well. The common solution seems to be to attach plywood above the flange using liquid nails + screws. My concern with this solution is that the bar would be partially touching the flange and partially on the new plywood, so they’d have to be perfectly flush for this to work. The second solution would be to use a 2×4 with a rabbit on it to slip over the flange, so the bar would be making contact only with the new wood (still using LN and screws to attach to the joists). The down side is this is way more complex, and would involve cutting a rabbit in a 2×4 to the correct depth.

Either way, the hole for the light is much closer to one joist than the other, so getting screws into the far one is going to be a PITA.

Any thoughts or suggestions?

View J's profile


70 posts in 2348 days

09-09-2012 09:00 PM

Perhaps you should look for an “old work” ceiling box, or an old work ceiling box with a fan support if you are mounting something where weight will be an issue.

Here is a picture of a kit, the rod for spanning the joists operates like a turnbuckle so you dont need to worry about screws in the end or cutting and patching drywall. Install the rod and attach the box with U-bolts, or whatever type of bolts your kit includes.

-- I found the board stretcher... finally!

View MarkTheFiddler's profile


447 posts in 2374 days

09-10-2012 02:05 AM


I used one very similar to what you showed us it works perfectly.

The thing is, I can’t see how the kit you are showing wouldn’t work because it should hit dead center on the I-Beam. The box would be at the right height.


Are the I=beams a wood product or a plastic product? If so, I believe they sell the brand of remodel brace in J’s post at Lowes. It should clear the the bottom of the I beam and get a really firm grip.

About the 2X4 idea. If you are trying to use celing brace you already own (and possibly can’t return). A table saw would cut the right depth for you in a few passes. That is assuming you have a table saw.

If you are working with minimal tools, I’d say skip the rest of the headaches and get the remodel brace that is intended to sit a little higher than the bottom of the flange and comes with a deeper box. That advice only comes from the experience of trying to make the wrong part work so I can save a few bucks. I think saving a few bucks has paid me about 50 cents an hour.

Best of luck to you and please share the solution that gets the job done.

-- Working on my home for 2 years and counting.

View Jimi_C's profile


9 posts in 3338 days

09-10-2012 03:13 AM

@J – I am using an old work kit very similar to that, however it looks like that one has a deeper box and thus the feet sit up higher. That might be all I need to get over the lip of that flange, so I’ll look at that one.

@Mark – The joists are particleboard. The old work brace I have was bought at Lowes (or HD, they sell similar stuff). I actually have two – one is a Westinghouse Saf-T brace and the other is Hubbel/Raco. I actually do woodworking as well, so I do have a tablesaw and dado set, so doing a lipped 2×4 wouldn’t be too much of a problem.

View J's profile


70 posts in 2348 days

09-10-2012 03:59 AM

In your comment to Mark I see you have the two available options; they should both work. All you need to do is set the adjustable bar at the right height and pick the metal box that meets your needs. It looks like you are there, right at finished.
I hope your project goes well.

-- I found the board stretcher... finally!

View HammerRussel's profile


1 post in 2064 days

04-25-2013 08:17 AM

I am with J on this one. That ceiling box should work fine to solve your problem. I am not an expert in this, but I had my brother over to help set up the ceiling fan box. Initially, we had trouble because the box was not flushed with the ceiling, but we managed to deal with it. You might need to brace yourself for possible mishaps, our ceiling fan actually fell on us as we were setting it up. Luckily, the blades are made of plastic. But once you are done, you will feel like you have accomplished a great achievement.

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12 posts in 885 days

08-27-2016 07:41 PM

This old work ceiling box really works. J has provided you with a good idea. Go for it!

-- Love my Work!

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09-29-2016 01:52 PM

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6 posts in 135 days

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