In article , Pudding Dot Man At Gmail Dot Com wrote:

Any signs/sources of extra moisture on that corner?

Not that I could see. Storm blew mostly west to east.
Flaky area faced east, was partially protected.

Freezing water in the mortar can certainly result in
flaking as described.

90% of it concentrated on about 1/8 of the wall area?

Sure. The fact that the flaking was so localized tends
to suggest (to me) that you do have some localized
moisture.

Assuming that mechanical damage is unlikely, it's hard
to think what else might cause the situation you
describe.

BTW, don't forget to consider what's going on in the
inside of the house next to that corner. A leaking
pipe inside the home is certainly a possibility.

--
|~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ ~~~~~~~~~~~~~~~~~|
| Malcolm Hoar "The more I practice, the luckier I get". |
| Gary Player. |
| http://www.malch.com/ Shpx gur PQN. |
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ ~~~~~~~~~~~~~~~~~~