"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.

That strikes me as a very good idea; thanks.