I have just purchased $5000 in thin brick for a 3ft high facade all the
way around my building, just under some old vinyl siding (we cut three
feet of the siding off at the bottom).
We stapled on black tar paper, then--don't laugh--screwed on cement
board. FWIW, USG claims that their product is fit for use in applications
including "exteriors" and "brick veneer."
Every kind of mortar we have tried on the cement board has failed to keep
the brick on solidly. The brick sticks into place just fine, dries, and
then falls off with the slightest vibration (e.g, a door closing) even a
day later. We tried to add a scratch coat on top of the cement board with
the same results.
We have tried Portland Cement grades I and N mixed with fine sand to a
consistency similar to stiff sour cream.
What are we doing wrong? If you can, please tell me how to do this
without removing the cement board. (PLEASE, PLEASE...)
Thanks to all the home repair gods that deign to reply!