On Aug 20, 5:13*pm, George wrote:

Our house is built of more-or-less solid cement blocks (c 1920, we
think.) *It has a lower roof that butts against the main wall, which
joint I need to flash. *My plan for the counterflashing is to cut a slot
along the blocks, to accept the 'top' of some rake edge, with the other
face of the rake laying down over the step flashing.

A single kerf fits the rake edge, but snuggly. *I can go with that, and
bed the rake in (silicon?) caulking. *Or, I can cut a wider slot
(1/4-1/2"), and bed the rake edge in mortar.

Any thoughts on the pros/cons would be appreciated.

This is how it's supposed to be done:
http://www.van-mark.com/Roofing/UniP...oInstruct.html

The top bend 'barb' locks the flashing into the reglet (that's the
term for the slot you cut). Another way to lock it in place is to
roll up small pieces of flashing that will just fit into the reglet
with the counter flashing in place, and then use a cold chisel or old
screwdriver to push the little roll into place, with a hammer if
necessary. Everything gets caulked in place with polyurethane caulk.

R