Installing Plywood between Metal C Studs

[TheStud]

I live in a 2018 built house. As such, the internal partition walls are all constructed from Metal Studs (looks to be GypFrame C Studs), which seems to be the "new way" of doing things.

I am looking to put a TV up on the living room wall. Having considered all the options (plasterboard fittings, Toggle Bolts into the studs etc). As it is large and heavy, the most secure way seems to be mounting plywood between the metal studs and then mounting the TV onto the plywood.

It looks like British Gypsum offer exactly what I need "04447/2 - Service Support Plates" which sits on the studs either side and provides a surface for plywood to screw to.

I see how it all fits together, however I have no idea what screws would be used and it doesn't say anywhere.

I would use the normal TV mount provided lag bolts into the plywood, but what screws are needed to Mount the wood to the plates and what screws are used to mount the service plate itself to the C Studs? So that they can sustain the load? From all I can gather, it is just dry-wall screws? But then, doesn't this seem to then defy the point? or because we would then need to re-plaster on top of it, does the screw type become irrelevant as it would be sandwiched between the stud and the plasterboard?

 

[noseall]

What you need to remember is that a large expanse of ply trapped behind plasterboard, need not actually be fixed to the studs at all for it to do its job as a recipient of load through the plasterboard. Obviously one would fix it in place or else it would fall or be pushed back as you try and fix screws into it, but the principal that the ply exists, means that you can fix through into it and you would need some humongous force to pull it through the boards.