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A 70" TV weighing 35kg is being mounted on stud partition wall using a fixed position TV mount which is 600mm wide. It will hit two studs approximately 230mm apart in the centre of the TV mount. While studs are normally 600mm apart, they are closer together beside a concrete column which is hidden by the plasterboard over it.

Behind the wall as it was being constructed

The wall has 12.5mm plasterboard over 6mm plywood over the stud partition.

The TV Mount (rated for 100kg) came with 6.3x55mm screws and wall plugs for use in a variety of materials - brick/concrete/wood.

Should I use the included screws or instead use Goldscrew Woodscrews or TurboCoach Coach Screws? If so, what diameter and length would you suggest?

Here's what came with the TV mount. Looks like they suggest driving the screws straight into the wood, however I assume for a screw of this size a pilot hole should be used?

Screws which came with the TV mount

  • The "W-A" screws are certainly strong enough. But I would go with a screw better designed - e.g., an easier to drive head, built-in washer (or wide head), etc. I don't think a pilot hole is needed - with the right screws and a good drill/driver. – manassehkatz-Reinstate Monica Nov 22 '18 at 18:04
  • That was the reason for my post. Which screws in particular do you think are better suited to the job? – Marcus Nov 22 '18 at 18:08
  • Screws like I listed in my answer or like you listed in the comment to my answer - i.e., longer than the original 55mm, sharp, wide head, etc. – manassehkatz-Reinstate Monica Nov 22 '18 at 18:15
  • These are hexagon head lags, nothing like a Philips head screw. Much easier to drive. The shank is big enough to warrant a pilot hole for each. 1/8" minimum. up to 3/16" maximum IF the screw is larger than 1/4". If you get much longer than 1 1/4" into the framing, the potential to hit a wire or something else covered by the wall is possible. – Jack Nov 23 '18 at 16:44
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The screws that is supplied with the mount are rated to do the job, the plywood layer under the drywall is the only additional layer that is not typical in woof frame construction. With that in mind, it is still thin enough so the screws will hold the TV you have, or any other TV. The rule of thumb I use is 1" of screw into the framing behind the drywall and the plywood. Your screws you have should give about 1 1/4" of depth into the framing. Get at least 4 screws into the wall and you will be fine. The shear strength of the screws far exceed the 70 lbs you will apply on them. IMHO....

  • Thanks. Think it should be ok with 4 screws into the studs which are fairly close together? Is it likely to be a problem if these 4 screws into the studs are off-centre of the TV mount if say I wish the TV to sit more to the left? – Marcus Nov 22 '18 at 17:49
  • Best would be if the center of the TV is somewhere in between the studs that are screwed to the TV mount. – manassehkatz-Reinstate Monica Nov 22 '18 at 18:13
  • Off center will still work. Just as a confirmation, attach the mount with 2 screws firmly with washers behind the head of the screws to the metal of the mount, and apply a downward pressure on one side, the screws, you should find if the pressure is applied gradual like the TV will, will hold fine. Adding 2 more screws will keep the mount in place more so. – Jack Nov 23 '18 at 16:38
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To translate to my US dimensions:

You have 1/2" drywall over 1/4" plywood on top of clean studs. The supplied screws are 1/4" x 2". Those are probably strong enough, but I would go with 2-1/2" or even 3" cabinet screws - something like these. There is normally a concern of "what if there is something inside the studs that you might hit with a screw. In this case, you have seen the open walls so that should not be a concern, so if it were me I would go with longer screws. 55mm - 12.5mm - 6mm = 36.5mm ~ 1.4". If you decide to use other screws, make sure they have a large enough head that they secure properly over the holes in the TV mount, or use appropriate washers together with the screws.

  • Looks like the equivalent over in the UK would be these: screwfix.com/p/… – Marcus Nov 22 '18 at 17:47
  • Yes, those screws are similar. They have a wide head (sort of like a built-in washer) and sharp end and threaded only partway - all of which makes sense in this type of setup (e.g., you don't need threads on the part in the drywall). – manassehkatz-Reinstate Monica Nov 22 '18 at 18:03
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I use those yellow or green, star bit deck screws from HD for nearly everything. because of the star bit, you can drive them deeper than drywall screws, which often torque out if you are driving long ones and hit a knot or some hard wood.

But, yea, nearly anything with enough length to get an good 1 1/2 or 2 inches into the stud will work. Use as many as you have holes for in the mount.

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for a flush mount the weight is in shear and strong screws are not needed, the supplied screws will hold about 100kg each.

  • If anything I was thinking the included screws are rather on the thick side. Good to know. – Marcus Nov 22 '18 at 18:06

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