Choosing the right wall anchor (bathroom shelf)

[AndersMoNi]

Hi member

I've a question on which wall anchors to use for a shelf, which I want to put up in my bathroom.
The wall is contains of 1,5 cm (0.6 inch) plasterboard followed by a thin metal plate (part of a larger metal frame). After the metal plate there's just "empty space".
The shelf I want to put up is pretty heavy (solid old wooden boards), so I want to use some strong anchors but not sure how the thin metal plate will affect the anchor. I'm currently considering the following anchor (attached image), but would like to hear your suggestion. I'm also attaching a picture of the shelf want to put up.

Look forward to your help.

Regards,
Anders

 

[Stanley services]

If the cavity is standard and not too large, and has masonry behind, I usually get a very long 8mm masonry drill bit. Drill directly through to the masonry wall behind as far as possible, place an 8mm plug on the end of a large 120mm-150mm screw hand tightened, then bang the screw with the plug attached into the hole with a hammer until bedded into the hole in the masonry behind.
Finally use an impact driver to drive it home. the shelf will then never fall off. Hope this makes sense.