RicodJour wrote:

More information, please. What exactly are you attaching? How much
does it weigh fully loaded?

The thing that's ultimately being attached is window trim. Not sure
about the weight, but I suspect not much. The trim was attached to three
approximately 4"x6" wood blocks nailed to an exterior brick wall.

I've never installed something like that before and don't know what is
the usual/proper way to do it. I just assumed that whoever originally
put that in place knew what they were doing.