Help with projector ceiling mount on I-joist


Old 01-30-15, 10:15 AM
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Help with projector ceiling mount on I-joist


I was going to attach the ceiling mount plate to the joist (two screws) but was surprised to find out the joist is not the lumber type but I-joist or engineered joist.

My projector is 16lb, the mounting hardware maybe a few pounds so total maybe around 20lb.

I would like to know if it is OK to attach the mount same way for lumber joist, i.e. screw in the center of the joist. Or, should I bolt on the flange off-center. I don't have a lot of space there, about 3/4" (See picture.)

Or: maybe I should not do either of these but strengthening the structure. And if so, what should I do?

Please see attached picture.

Thank you very much.
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Old 01-30-15, 01:57 PM
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I've been looking at this thread for a while. I can see your problem but I'm not really sure how to rectify it. I thought the piece of wood at the bottom of the engineered joist was a 2x4 but your measurements appear to be smaller.

I would think that putting the lags in the center would be the strongest mounting choice. Definitely would need to predrill thru the "2x4".

Wait to see what others have to add to this.

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Old 01-31-15, 06:19 AM
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Hopefully you can get to the joist to mount a piece of plywood to the top and bottom runners. This locks the runners together so the bottom can't separate. Once that's done you can use U-clamps to hold the projector mount's vertical pipe.

You could use two pieces of plywood facing each other with a 2x6 between them to provide a plate for the mount.

Either way, it will be easier if you attach the hardware or build the plywood frame before you mount it to the joists. Those are supposed to be carriage bolts on the plate.

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Old 01-31-15, 06:31 AM
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I agree with Rick and Pete on their solutions, but an I joist won't come unglued with 20 lbs attached to it. I have tried to uncouple them just for grins, and the only thing left was the glue with shards of OSB and 2x lumber. I WOULD be concerned that the fasteners you use may not hold the weight. How wide is your attachment plate? if it is wider than 1 3/4", then you need to do as the second drawing of Rick describes to give a solid plate-to-plate connection.
Old 01-31-15, 12:05 PM
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Thank you guys for your input.

Rick's picture is really nice. I searched this problem for a long time and could not reach this picture.

I decided to just screw into the center per Pete's suggestion. I am using two 1/4X1-1/4 lag screws. The plate is large but only two screws for mounting into joist. I hope this is strong enough?

After a few months I will check everything and if something is not quite good, I will add plywood or 2x4 like in Rick's picture.

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