On 11/02/2020 00:49, williamwright wrote:
On 10/02/2020 15:13, newshound wrote:

Personally I would put in high quality plastic plugs and something
like 5 inch No 12 screws if fixing directly. In fact, since you need a
spacer I would probably screw that securely to the wall, and simply
screw the bracket to the spacer. This has the advantage that if you
"lose" one or more screws to soggy mortar, or similar, you can put
another screw somewhere more secure. And also locate the bracket
exactly where you want it, and get it exactly upright.

What's more you can temporarily put the baseplate on the spacer and
drill right through it, then put bolts through from the back (run epoxy
along them before insertion) and then when the spacer is fixed to the
wall put the baseplate on it and hold with nuts. Dremmel the thread
flush with the nuts.

Bill

Agreed, if you actually need bolts (as you might with a slimmer spacer).
But if you have 50 mm of solid wood, or even three layers of 18 mm
plywood (which I would glue together) you can probably fit the bracket
directly using 2 inch No 12's (or the metric equivalent).