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Advice on Installing Cantilever Mount on Half Concrete, Half Ply-reinforced Drywall

154 Views 1 Reply 2 Participants Last post by  pilotart
Hi all,

Apologies in advance if this is wrong section of forum. Saw some other mounting threads in this one though. Need some help on how to safely mount TV / recommended hardware and installation location on wall.

My predicament:
* I have a pretty heavy TV (85 pounds) and mount another 25lbs, and trying to get mull-motion/articulating mount safely on my wall.
* I had my contractor put in 1.5" of plywood attached to two metal studs where the mount would be installed on the drywall
* To center the TV with my couch, it would involve putting one end of the mount into 8" thick concrete/masonry while other half on the drywall

I'm not installing this myself (will have another professional do it) but I'd like to make sure I understand the recommended hardware/approach.

Couple questions:
1a. If the mount is installed partially on concrete and partially on drywall, any major issues with that?
1b. I've heard toggle bolts recommended. Would those be drilled/installed where the stud or into the plywood backing
2a. If want to move the TV/couch over to the right so that the mounting bracket would be fully on the metal studs, is this ill-advised or does the plywood give it enough support?
2b. If the bracket supports stud spacing between 16-24" and my studs are 24" apart, should holes be drilled into the plywood or drilled into the metal studs? I wasn't sure if the plywood is meant to the be location where the mount is attached, or does mount still get drilled into metal studs and the plywood helps with weight bearing.


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You need to know the exact composition of your 'concrete' wall.

If its CBS you must avoid mortar joints and best strength is not near the center of any block, you drill into a web.

In my case, I had a solid (reinforced concrete) perimeter cap beam above CBS and frame construction above that.

I had to insure that the top (of three) lag bolts was securely into the cap beam. This was the mount I had to use:

My Wall did not allow for other than a vertical alignment of mounting bolts. The top lag bolt takes most of the stress.

I had taken photos during construction, as all the details were now hidden behind a final layer of insulation and dry-wall.

The 'studs' (1 x 2 wood) between Concrete and CBS were in no way sufficient to hold mount, they just provide space for insulation and for attaching dry-wall, but they were very important as a spacer and I had to be sure to mount with the bolts centered over their location.

My alternative (had I not known construction details) would have been to remove dry-wall and insulation down to concrete. This would have also cost me a couple inches of my mounts extension arm's distance from the wall. :cool:
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