drywall-anchorwalls
I need to hang a 25Kg mirror on a wall, however I do not know what type of wall it is, I think it is possibly plasterboard or thermalite blocks.
I have been looking at various fixings online, and you get a lot of variation between plasterboard and thermalite wall plugs, and also wall plugs that can be used within different wall types.
Is is best to drill the wall and find the wall type and use those specific wall plug types, or buy the wall plugs that are suitable for any wall type?
Sounds like you're dealing with a pressure sensitive vinyl. It's not going to go down with out a fight. The best course of action is to hit it with a heat gun and very slowly pull with light steady pressure, let the heat do the work. If you do it right the adhesive will detach from the wall and the vinyl in about equal measure, which of course means you'll have to deal with the residual next. If it's the kind of adhesive I think it is, Goo Gone works okay (or any of the orange oil based cleaners) but Rapid Remover is designed for the job. If none of those will touch it then it's something solvent based and you'll have to step up to something with acetone in it (Goof Off) but test a little spot first to make sure it's not going to ruin your paint. He's a link with a bit more information. http://www.signwarehouse.com/blog/a-basic-guide-to-vinyl-removal-options/
It's probably double 5/8ths drywall, I'd use toggle bolts. And then washers and 3" deck screws to the stud for safety (not drywall screws), even if you're going to do all four corners with toggle bolts. There should be some one-by inside the cabinet at the top (and possibly the bottom) this is where you want your fasteners penetrating, not just through the flimsy back panel. Your local hardware store should have these:
1/4" x 4" Toggle Bolt: (tannerbolt.com)
You can skimp on diameter if you want, but the shorter they are, the harder it's going to be to install all four at the same time. The size shown is my go-to.
Hand tighten only, or you risk stripping the tiny nut in the spreader or compromising the drywall integrity. You need to be able to feel what's going on in there; they should just be snug. Be extra careful with smaller diameter toggles as they have even wimpier nuts.
Other types of drywall fasteners are discussed here: What benefit do plasterboard drywall screws have?
Best Answer
In the case of either plaster or Thermalite panels, plastic plug-type anchors should suffice. I'd use those sized for a #12 or #14 screw of adequate length (per the anchor manufacturer's suggestion), and be sure to drill exactly the correct size.
Be sure that you only leave the screw protruding only as far as necessary to allow the hooks to engage. Torsional force is what tears anchors out of walls, so you want to keep the load tight against the wall.