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I am trying to mount a 75" TV in my basement, and upon initial investigation, the studs behind the drywall are mounted "sideways". Sideways as in the 3.5" side is facing the wall meaning that I only have 2" of wall through the drywall and the stud itself. Ideally the studs would have the 1.5" side facing the wall which would give me closer to 4" to drill the screws into. Giving that I only have 2", can I simply use the same screws that came with the mount (60mm lag bolts) and drill those through the wall and stud or do I need to get something smaller so the screws do not protrude?

I am assuming having 2" of wall is sufficient to support this mount and TV as well?

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  • Agree with the answers. However, if the studs were poorly attached and the mount feels loose -- like it's moving the wall -- you could get a couple of tapcon style concrete screws into the mix and make everything solid.
    – Aloysius Defenestrate
    Jan 14 at 22:43
  • Where should these be added? Should they be in addition to the 4 1.5” lag screws through the mount?
    – kschins
    Jan 15 at 0:34
  • You could either add tapcons through the mount (where there’s wood behind the drywall) or just through the wood. If the latter, drive the screws all the way through the drywall.
    – Aloysius Defenestrate
    Jan 15 at 14:20

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It will work just fine, but replace those lag screws with shorter ones.

I'm assuming that the reason the studs are parallel to the drywall is because the exterior wall is concrete and whoever finished the basement wanted to retain as much interior space as possible.

Aside from a little bit poorer insulation capability, this is just fine. The walls aren't bearing any load other than themselves (and what ends up mounted to them).

Most of the time when I see blocking added to a stud wall for mounting, it is installed just like that - with the longer dimension against the drywall. Make sure that you use lag screws that are 2" or less in length (1.5" stud + .5" drywall + the width of your mounting plate) so that you don't go all the way through and hit the concrete wall.

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  • Thank you! We just bought this home (old brick home) so the reason they are sideways is exactly due to this -- save room in the basement and the bottom half of the studs are up against a concrete foundation while the top half is a crawl space so we do have access to the back of the studs where I will be drilling. I will get < 2" lag bolts then to use.
    – kschins
    Jan 14 at 19:19
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    Use a fixed, not articulating, TV mount. If the top half of the studs is "sideways" and is unsupported by the concrete wall, so long as the tops of the studs are strongly fixed to the header you should be fine but I wouldn't push it, A very big TV, short screws, and sideways studs are three factors. Don't add a huge fourth one with an articulating mount.
    – jay613
    Jan 14 at 19:38
  • Yeah, my mount is fixed. Is it better to get 1.5” lag screws or use a carriage bolt through the stud with a nut on the end?
    – kschins
    Jan 14 at 20:42
  • Additionally, there's nothing wrong with adding more of the shorter lag screws too. Many wall mounts have more holes than they need, for versatility; may as well use them.
    – Criggie
    Jan 15 at 6:00
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The depth of the screws should be about 1in into lumber (past drywall) to provide sufficient pull-out strength. The available depth of 1.5in vs 3.5in matters little.

If there are insufficient fastening points available use a larger diameter screw, e.g. a #10 screw, a lag bolt, or a structural screw. Generally this is a much better approach than using long screws.

Moreover, any in wall wiring or piping (invisible to you) must have been kept at least 1.25in from the edge of the lumber. Thus fastening with screws longer than 1.5in (1in penetration plus 0.5in drywall) poses a risk of damaging wires.

The stud deflection due to the TV's load forces does depend on the orientation of the stud.

Deflection applied to the edge is far less than on the face, but very likely either case is sufficient for your TV, assuming it's a contemporary LED flat screen and you have at least 2 such studs available. If you are using an extendible arm we'r have to calculate the deflection and determine whether it might crack the drywall over time.

But risk of failure of the mount is not the issue. It is not uncommon to fasten sinks or other heavy hardware to a panel of plywood or to 2x4 or 2x6 backing lumber facing forward.

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