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Discussion Starter · #1 ·
If I had solid wood joists, no big deal, but I'm not sure how to work with these i-joists. Sounds like you can't hang weight from them, they are designed to support weight on the top only. Anyone have a projector hanging from i-joists? I'm looking at buying an Epson 5050UB asap and I'm undecided on a mounting device model yet.


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If I had solid wood joists, no big deal, but I'm not sure how to work with these i-joists. Sounds like you can't hang weight from them, they are designed to support weight on the top only. Anyone have a projector hanging from i-joists? I'm looking at buying an Epson 5050UB asap and I'm undecided on a mounting device model yet.


Thanks!
They can support weight but the screws should be driven into the centre of the joist as flange size is often less than on a conventional joist.
 

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If it's finished in sheetrock, just use as many attachment points as you can to distribute the load. It isn't going to fail unless you put something really heavy concentrated in a single location of the bottom flange.

Ideally (for those who may run across this thread and have joists exposed) you would use blocking (dimensional lumber cut to fit between top and bottom flanges) glued and screwed to both sides of the web at attachment points. Screw through the flange into the blocking. If you need to attach between flanges use the same blocking on two adjacent joists and span with short header.

The bottom flange is glued to the web and that joint is designed to take shear loads and not a lot of tension. Drywall is screwed into the bottom flange and it handles that just fine. I wouldn't fret over double layer drywall either. Those loads are distributed over plenty of fasteners. So most PJ's with reasonable fastening would be just fine. On the other hand, I wouldn't use a single pair of eyebolts to hang a swing on my front porch and sit in it with my wife and children. I've never been a lucky gambler.
 

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Discussion Starter · #9 ·
If it's finished in sheetrock, just use as many attachment points as you can to distribute the load. It isn't going to fail unless you put something really heavy concentrated in a single location of the bottom flange.

Ideally (for those who may run across this thread and have joists exposed) you would use blocking (dimensional lumber cut to fit between top and bottom flanges) glued and screwed to both sides of the web at attachment points. Screw through the flange into the blocking. If you need to attach between flanges use the same blocking on two adjacent joists and span with short header.

The bottom flange is glued to the web and that joint is designed to take shear loads and not a lot of tension. Drywall is screwed into the bottom flange and it handles that just fine. I wouldn't fret over double layer drywall either. Those loads are distributed over plenty of fasteners. So most PJ's with reasonable fastening would be just fine. On the other hand, I wouldn't use a single pair of eyebolts to hang a swing on my front porch and sit in it with my wife and children. I've never been a lucky gambler.
So let's say I cut out a piece of sheet rock, the idea is to cut a 2x4(?) that would fit between the webbing and rest on top of the bottom part of the i-joist and then it would be glued and screwed into the webbing from the outside of both i-joists and then the mount would screw into the 2x4 piece that was added in?
 

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OK, for a 25 lb projector, this isn't needed. If you didn't have sheetrock, then sure why not "do it right." But with sheetrock there's no way I'd sweat it for 25 lb. Just use a small mounting plate screwed across two joists and a few screws into each. Not only would that be fine, but the lower flanges are resting on sheetrock screwed to an even larger area further distributing the load.

That being said, for reference, you'd want at least the solution seen in the pipe support image on this page.

https://www.weyerhaeuser.com/blog/supporting-exercise-equipment-with-tji-joists/

Better yet, span from bottom to top flange like the backer block in this pic

https://www.florenceapartmentsmm.com/4857/11/

The idea is to support the weight by the web at worst if it can't be supported from top flange.
 

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Discussion Starter · #11 ·
OK, for a 25 lb projector, this isn't needed. If you didn't have sheetrock, then sure why not "do it right." But with sheetrock there's no way I'd sweat it for 25 lb. Just use a small mounting plate screwed across two joists and a few screws into each. Not only would that be fine, but the lower flanges are resting on sheetrock screwed to an even larger area further distributing the load.

That being said, for reference, you'd want at least the solution seen in the pipe support image on this page.

https://www.weyerhaeuser.com/blog/supporting-exercise-equipment-with-tji-joists/

Better yet, span from bottom to top flange like the backer block in this pic

https://www.florenceapartmentsmm.com/4857/11/

The idea is to support the weight by the web at worst if it can't be supported from top flange.

Bigus, double checking. Are you saying that because it's already a finished ceiling, I should just get a projector mount of some sort and make sure it attaches to the bottom of two different i joists and call it good?
 

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That looks unnecessary. Do you already have sheetrock installed? If so, then screw a piece of decent quality plywood (so it doesn't warp and will finish nice) against the bottom side of the sheetrock. Hopefully you can find the joist locations with a stud finder if the sheetrock is already finished and painted. Size the plywood so that it spans at least 2 joists. These are often but not always 16" apart. Sometimes 12, sometimes 24. A square piece of plywood would be fine. Use several deck or wood screws into the flanges of each joist. You're only supporting 25 lb, it isn't a big deal. Paint the plywood to match ceiling, or a complimentary color, trim edges if desired.

Sorry if my earlier post lead you down the path of thinking any of that was necessary for a 25 lb projector. It isn't. But if it we're just exposed joists still, then sure why not.
 
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