Plasterboard walls - what size fittings what weight?

[dob22352]

Hallo!

I live in a steel frame house (i.e. no battens I can get through with my equipment) and 2 kinds of wall:
a) 12.5 fireline wall with 25mm quilt in the void
b) 12.7mm fireline with open cavity (I think 25mm) behind.

1. I am wanting to put up a towel rail through tiles in my bathroom. The tiles are on a 12.5 fireline wall with 25mm quilt in the void. The tiles are c. 5mm thick. If I am to use heavy duty plasterboard fixings with wings, then that involves making a gigantic hole in the tile. What size and length do I need? What size drill bit will it involve? The fixings will have to be long enough to get through the whole wall, including the tiles. Detailed recommendations requested!

2. Is there any rule of thumb as to what weight these 2 kinds of plasterboard walls will carry without potential disaster? I realise it will depend, to some extent, on how many fixing point - visualise, for example, a rectangulat mirror which could have one one or two fixing points.

Thanks.
C

[thedoctor]

No rules of thumb I'm afraid but there are, in most DIY Stores, plasterboard fixings especially for bathroom/kitchen tiled walls. Our fixing to ceramic tiles project will be published by tomorrow dinner time so click into the website to see this.