But the j cap also creates a consistent line.
Flashing between siding and brick.
The metal flashing placed on wall top slopes back towards the building directing water inside the structure.
Details like this risk rot and insect damage to the structure.
In your case there is a great need for a flashing that runs along the top of any of the horizontal fascia boards.
You need to make sure each material sheds water over the top of the material below without getting behind or under the materials.
Transition from brick to siding.
My detail only shows how it should be capped and flashed if you do build it as shown.
It might be buried behind the siding where you can t see it.
Using a metal j flashing between these types of transitions provides a barrier between siding and transitions that protects against water intrusion.
Maybe in this case the flashing extends upwards behind the building siding forming a zee shape that might reduce this risk.
There should already be a metal flashing that is sealed to the brick.