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I need to build a brace to support this light fixture in my dining room.

enter image description here

The eyelet screws on either end should be attached to the existing ceiling joists. However, mine run opposite the direction that I need them to. My plan is to cut 2x8 supports and fasten them between the joists, then attach the eyelet screws into the new supports.

I am considering running a length of metal rod through the new supports so that I can hold it more firmly in place using washers and nuts on either end. Overkill? Would this add any structural benefit or just wishful thinking?

Do I need to leave a gap at the top of the supports for airflow? I am concerned about trapping heat from the electrical box in the cavity that I'll be creating. If a gap is needed, how much space should I leave at the top?

Any other concerns for mounting a very heavy lighting fixture?

enter image description here enter image description here

EDIT: Clarifying one proposed plan:

enter image description here

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  • 1
    How much does that fixture weigh? I think 2x8 blocking is a little bit overkill and metal rods are unnecessary. Are you sure that the eyelet screws are intended to connect directly to the joists and carry the load? The eyelets don't look to be in the right configuration to do that in most cases. Can you post additional pictures of the reverse side of the base plate and the location in the attic (and the electrical box location) where you want to mount this? Sep 13 at 12:15
  • @GregNickoloff The 48" beam weighs about 80 lbs. I believe you're right; the eyelet screws are too short to go through the (wood) base plate, drywall, and into the joists. The base plate is the same on both sides with only a cutout for the wiring. The dining room is on our first floor with a bedroom, not attic, above it. Picture of the current situation has been added to the original post. Thank you!
    – Yuck
    Sep 13 at 12:50
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    "running a length of metal rod through the new supports " - unnecessary, decent construction screws are good for nearly 1000lbs pull out force apiece. Sep 13 at 15:31
  • Honestly, consider digging out 3/4 of the mass by emptying the center of the wooden beams. That's a LOT of weight to suspend over people. Noone will see down into it.
    – Criggie
    Sep 14 at 4:35
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    I'd definitely ensure that this could also support the weight of someone hanging on it. just in case. Sep 14 at 13:00
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You could attach blocking to the joists on both sides of the existing electrical box and bracing, etc.

By attaching the blocking vertically, you will maximize the weight capacity, but by attaching horizontally you can provide a larger area to "hit" with the mounting hardware. Both orientations should support the weight adequately. Sections of 2x4 mounted vertically would easily support the weight, but you might use 2x6 or 2x8 if you mount it horizontally to maximize the surface area.

Make sure the blocking is as tight as it can be between the joists (within reason) and the ends are nice and square, etc. then fasten with 3-3.5" construction screws through the joists. Mount the blocking so that the bottom surface is flush with the bottom surface of the joists. sketch of joists and added blocking, etc.

Attach the "base plate" of the lighting fixture through the drywall to the blocking. You can use "old fashioned" looking lag screws to attach the block. These are available at BigBox, etc. and will match the ironwork on the fixture.

Stylized fastener example Example fastener

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  • This was intuitively what I had planned on doing. I'm glad to see that it's a suitable solution. I wish I could give points to (or buy a 🍺 for) everyone who responded because all answers helped me think about this problem better.
    – Yuck
    Sep 13 at 19:29
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    I'm always up for a beer! Next time you're in Toledo.... You can up-vote everything for a few points to everyone...if you haven't already. Sep 13 at 19:37
  • @Yuck This is a very good solution, when Greg mentions construction screws, pick a good brand like Spax. The rated shear load will be printed on the packaging, so with the load divided by 12 screws, you can see just how much overkill you are applying to support your 100lb fixture!
    – Glen Yates
    Sep 13 at 21:36
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    @GlenYates: FYI, shear strength is not what holds anything up in this situation. The shear load on the screws will be pretty much 0. Frictional force between the joists and the blocking is what holds everything up, the screws are just there to ensure that that frictional preload is present. Shear strength in many screws is pretty miserable compared to their their tensional capacity, but that's OK. This is also why several of us have mentioned to make sure the blocking is square and fits snugly before tightening in place. Sep 14 at 3:39
  • I ended up doing this with one 2x8 on either side of the box. Base plate will be mounted parallel to the joists. The 2x8 pieces are attached through the joist with 3 Simpson Strong-Tie #10x3-1/2" screws. As mentioned I don't believe these are actually providing load bearing support. I will use 1 3/8x4-1/2" screw eye to hold each side of the beam. These are rated at 155 lbs each (DuraSteel part number 320133).
    – Yuck
    Sep 15 at 1:29
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Update after seeing the fixture image:

There's no need to bolt the box to the support framing other than to secure it in position. Nothing hangs from the box (so it doesn't even need to be fan-rated). I would still run the 2x10 over the box, and I'd add blocking on each side of the box to bring it down flush with the adjacent joists. This will give you solid backing for the fixture board and/or the eye screws.

|  |__________________________________|  |<-- joist
|  |__________________________________|<-|--- backing board
|__|____________||_____||_____________|__|
                   ^                ^
                   light box        spacer block

A 2x10 spanning just ~15" will carry that load without breaking a sweat. It's all a matter of good fastening.


Earlier answer:

I would run a 2x6 or larger, laid flat, over the box. Secure it with at least three 3" gold construction screws or two 1/4"x3" lag screws at each end. Bolt the box to it. (If the box you have now isn't fan-rated, upgrade it. You need the mounting screw holes for the fixture to be robust enough for the job.)


Heat escaping electrical boxes isn't generally a concern. If it was, all boxes would be required to have clearance or insulation. If enough heat is being generated to cause a safety issue, something's badly wrong with the wiring.


Unsolicited protip: Next time you cut a hole in drywall for repairs, leave an inch or two extending past the adjacent framing. This way you can float backing for the patch without having to fasten it to the existing framing. It's much quicker and doesn't require careful positioning.


Engineering point of interest: The chains on that fixture hold approximately twice the weight you might think. This is because of their angles. Whereas a vertical chain would hole more or less half the weight of the fixture, they now hold roughly the entire weight of it... each. Load force increases exponentially as the angle strays from vertical. If you're selecting chain yourself, be sure that it's up to the task.

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  • Thanks, I added a photo of a 2x10 to illustrate my understanding of what you're suggesting. Would I remove the existing brace and support straps? Seems I'd need to in order to fit the 2x10 (or even 2x6) in there. And would I just screw the box to the 2x10 once it's in place? What prevents the 2x10 from buckling in the middle?
    – Yuck
    Sep 13 at 15:33
  • @Yuck the cross bracing is designed to prevent the joists from twisting. When you put your 2x in there, you'll be adding significant stiffness that will help prevent this twisting.
    – FreeMan
    Sep 13 at 15:51
  • Answer revised now that I can see the fixture.
    – isherwood
    Sep 13 at 16:04
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    Instead of using the backing board, could I just use a 2x6 on either side of the box flush with the bottom of the joist, securing those with lag screws. Then attach the base plate using the eye screws through the drywall ceiling and into those 2x6? It seems like that would be simpler as long as it's still sufficient for that weight.
    – Yuck
    Sep 13 at 16:29
  • Now you're carrying all the weight on what's essentially a hinge. Those blocks can flex downward, putting huge force on the screws. It would probably hold, but it's nowhere near as strong.
    – isherwood
    Sep 13 at 16:45
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This is what I would do personally:

Support

I would get a 2x8 or larger, cut it to fit the width, cut a notch to fit the box, the fasten that between the joists. Make sure you cut the width of that to fit as snugly as possible without having to excessively force it in, gentle tapping with your fist is ideal. Put 3 or so screws such as these DeckMate screws on each side. The resulting structure will be sufficiently rigid that the joists will come down before the light support does. Secure the upper board with the eyelets to this 2x8 with similar screws with the right aesthetics, such as these low profile screws. Secure the box with the same screws you use to secure the support.

The notching of the bottom of this support is a non-issue, even a 2x4 spanning the joists would be enough to support the light fixture. A notched 2x6 is going to have plenty of leftover rigidity, 2x8 or larger just increases the already-plenty safety factor.

Definitely use a fan rated box, as maybe 20 years in the future you'll want a new aesthetic and might put a fan in or something else that needs to be supported entirely by the box.

Edit: if you are mounting the base plate parallel to the joists, then just do this with two 2x6s in the right position to place the screws through the baseplate in attractive locations, and forget about the notching. Again, even a pair of 2x4s is more than enough for the task.

If mounting perpendicular to the joists, and the position of the eyelets are such that they are outside the joist space where the box is, then it would make sense to do the above, with a support on each side of the box's space.

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I suggest running a 2x header between the joist and level with the junction box. Then hanging the fixture on the eyebolts that fastened on the 2x. It will be much sturdy.

enter image description here enter image description hereenter image description here

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  • I wouldn't do this with bolts, as it will be such a pain in the neck when you want/need to remove it. Screws of some sort are a much better bet, as they can be withdrawn without ripping out the whole ceiling. Sep 14 at 9:52
  • @MikeBrockington THe solution is simple, see the updated sketch.
    – r13
    Sep 14 at 13:49
  • What is the purpose of the second/lower nut? (I would still go with an eye-bolt with a wood-screw thread on it - so much simpler.) Sep 15 at 8:49
  • @MikeBrockington The top nut carries the weight, the bottom nuts to prevent the bolt from wobbling.
    – r13
    Sep 15 at 14:00
  • @MikeBrockington Yes, the screw is simpler for the majority of works, but for hanging heavyweight and movable overhead items, there is a chance the screw may split the wood due to its large size, and pull out from the wood while shaking back and forth during an earthquake event. My philosophy for such construction is always "better safer than sorry".
    – r13
    Sep 15 at 14:47

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