Question Can I safely mount to the bottom chord of a truss?

stevetb77

Novice Member
I'm finally going to ceiling mount my Sony HW40ES projector after 1.5 years of use.
My ceiling is vaulted. I'm using the Chief CMA395 vaulted ceiling adapter (mounting plate) and Chief RPMAU mount. I suspect the whole thing (including projector) weighs around 35 pounds.
I've read it's perfectly safe to mount something like this to ceiling joists. However I learned recently that this is technically not a joist, but actually the "bottom chord" of a truss. I can't find a definitive answer (at least that I can understand) as to whether or not it would be safe to mount to this bottom chord or not. The chord is about 1.75" wide, so I need to get right in the center if I do it (using two 3/8 x 2 1/2" lag screws per the instructions).

My gut tells me I'm ok.. but from what I read bottom chords can't support nearly as much as joists...
Wish I had a clue. =D

This is kind of my only option next to shelf mounting, which I don't want to do for logistical reasons. It would be great if I could rig something in the attic between bottom chords, but I haven't successfully been able to get myself all the way down there to that area. It's extremely narrow, and I'd have to literally inch out of that tight spot going reverse against gravity. Not easy.

I appreciate any feedback, thank you!!!

Projector / mount
1.jpg

I want to put it about where the black dot is
2.jpg

It is very close to the wall, I imagine that would be a even stronger than putting it further up.
It has to go close to the wall to fill my 135" screen.

**Correction - the wood is just a hair under 1.5" wide where I want to mount. I just made holes to check.

Update:

On the way down..
3.jpg

Using laminate flooring planks to support my weight I managed to shimmy myself nearly there..
My hands can reach where I intend to place the 1st lag screw.. but I have to basically have my head sideways to even fit this far. Not for the claustrophobic! I don't think I would effectively be able to do any rigging from up there due to being wedged like a sardine.. though I suppose I could remove a large piece of the sheetrock from below(?). My preference is just to mount to the chord from below and be done with it, as long is truly is a secure thing to do.

And here's where I want to attach to from below:
4.jpg
 
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stevetb77

Novice Member
Thanks Dan! I'm not so concerned about the projector falling.. the ceiling mount plate can supposedly hold up to 500 lbs. I was more concerned about damaging / weakening the truss. I wasn't sure if it was smart to hang anything from a bottom chord or not.

Should be fine. It's certainly not going to just fall off without some serious force applied to it.

Dan.
 

stevetb77

Novice Member
Yes there is an attic, and there is a crawlspace over this vaulted ceiling but it is extremely narrow at the point where I want to mount. It narrows as it goes down. I'm not sure I'd be able to make it down to that point. Past attempts to do so failed. If I did succeed, I'm not sure I'd ever be able to make it out. ; )
 

paulyoung666

Distinguished Member
That's a shame, I was thinking about adding some studding in to make extra sure, don't suppose you have a small child you could employ lol !!!
 

stevetb77

Novice Member
LOL, I do but the attic looks like scenes from many horror films. It's the last place that kid wants to go. ; )
When you say add some studding, are you talking about some 2x4s or something between the two adjacent chords to help distribute the load?
Ya if I could get down there I'd probably just rig it between two chords..
 

BrianC1

Active Member
Trusses are in tension and not usually sized for resistance to bending forces. Depending on the construction, there may be ceiling joists up there or the trusses may be acting as ceiling joists. If the bottom chords are supporting the ceiling all by themselves they are also acting as joists and should have been sized accordingly. I imagine it is about 100mm deep and if so 35 pounds near the end should be no problem. But you do need a good look at this truss/joist from above!
 

stevetb77

Novice Member
I updated my first post with pics from above, thank you!

Trusses are in tension and not usually sized for resistance to bending forces. Depending on the construction, there may be ceiling joists up there or the trusses may be acting as ceiling joists. If the bottom chords are supporting the ceiling all by themselves they are also acting as joists and should have been sized accordingly. I imagine it is about 100mm deep and if so 35 pounds near the end should be no problem. But you do need a good look at this truss/joist from above!
 

BrianC1

Active Member
If it's a piece of 2x4 I really don't see that there will be a problem.
 

BrianC1

Active Member
Better still, don't use lag screws. Use structural screws. No pilot holes needed. Much easier.
 

stevetb77

Novice Member
Wow thanks for the replies everyone, I really appreciate it!
BrianC1 thanks for the info on the structural screws.. unfortunately I had already drilled the pilot holes before I saw your post!
 

BrianC1

Active Member
I trust it wasn't a problem!
 

stevetb77

Novice Member
The instructions for the ceiling mount say to use 3/8 2 1/2" lag screws. I was thinking that if I cut out a small piece of sheetrock I could get access to use 3/8 4 1/2" hex bolts with a nut and a washer on top. Would that be a stronger hold? I'm paranoid about this kind of thing.. the thought of a screw holding this in place against gravity with nothing bracing it on the other side makes me nervous. Perhaps that is due to my lack of knowledge regarding construction / building materials. I live in California. I'd like to know that my projector isn't going down in a Quake unless my house falls too. ;)
 
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