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I need to fix a 65 inch TV to a wall that is made of plasterboard on 18 mm OSB. These are fixed on with metal stud/rails at 600 mm intervals. My worry is the OSB isn't thick enough to hold the TV on its own, and the metal studs offer nothing to fix into of any great note. Any advice would be appreciated.

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Dave Thwaites
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  • I will point out that a lot has to do with how far out the unit "hangs". If it's pretty much flush to the wall, there's relatively little outward-pulling force on the fasteners, and you should be in pretty good shape. But if the mounting system holds the TV out 50cm from the wall then there's a lot of force pulling forward on the top fasteners, and they need to be anchored into the studs. – Hot Licks Jul 24 '20 at 22:48
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    I assume your TV has a VESA MIS-F mounting pattern with either (or several) of 400x200, 400x400, 600x200, 600x400, 800x400 mm hole patterns. The norm is designed for up to 113.6 kg, but your TV is a lot lighter. As pointed out above, lever forces to the wall depend on the distance wall-TV (and this also limits features such as possibility to rotate the TV). Wall mount kits for VESA MIS-F (if applicable) are available online and come with their own weight restriction, but mounting itself should be less problematic (see answers) because in the end you do not fix it only to plasterboard. – Hagen von Eitzen Jul 25 '20 at 11:13

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Assuming that "plasterboard on OSB" means that the studs were first fully covered with OSB, then that was dressed up with plasterboard for a nicer finish, you have a very sturdy wall! I just build a storage shed using 3/4" (~18mm) plywood as the floor. I expect it to hold 100s of kilos at the contact points for each of the shelving units.

If this is how your wall was built, you've got the added advantage of being able to put the TV anywhere you want because with the proper bolts, you don't really even need to worry about hitting a stud, that 18mm OSB should hold your TV without a second thought. Of course, hitting a stud is an added bonus, and will take the proper sheet-metal screws to get a good grip into the steel studs.

If you're referring to OSB on the outside of the building and drywall on the inside, then this advice goes out the window, use sheet-metal screws into the studs as Ecnerwal suggested. In either case, you have nothing to worry about.

FreeMan
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    Yes, you're quite right. The steel studs are fully covered with OSB, and then it's plasterboard on the top. That's quite reassuring then. I'll go ahead and get this thing hung up. Thanks for your help everyone. – Dave Thwaites Jul 24 '20 at 12:44
  • @DaveThwaites Is this a standard construction method where you live, or is this just an odd DIY one-off? If the former, I'd be interested to know where in the world builds houses like that! – J... Jul 24 '20 at 20:27
  • Seems like a shearwall, perhaps earthquake-code related, or it might be multifamily party-wall construction. – Ecnerwal Jul 25 '20 at 01:16
  • Its in France. We have a lot of thick, rubble construction walls that are usually lime motar. They're also surprisingly inefficient from an insulation perspective so in order to insulate and let the wall 'breathe', we erect internal metal studs about 120mm (or depth of insulation) from the wall, and then osb and plasterboard over the top. We don't use wood here, since in the alps temperature swings from -20 to +40 and the 2x4 wood will warp. – Dave Thwaites Jul 25 '20 at 13:08
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    @DaveThwaites You don't use wood there, but the temperature is not the reason. We use wood framing in Canada and the temperature here can swing from -50C to +40C. I suspect that wood would need extra materials to protect it against the dampness that can form in mortar walls. If the building was purely timber framed it would be fine. – J... Jul 25 '20 at 17:26
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Use proper sheet-metal screws into the studs. "Self-drilling" screws will save a step, or you can pre-drill the proper size hole for the screws.

Your worry is unrealistic - steel studs are quite robust.

Ecnerwal
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With 18 mm OSB attached to steel studs and drywall over that the wall is very strong. I don't think it would be necessary to screw the bracket into the studs. Four appropriate screws into the OSB should be sufficient with a safety factor, and no more than six would possibly be needed. This assumes that the bracket is fixed and holds the TV close to the wall.

Jim Stewart
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