Wall question for brick layers.

[Doctor Zoidburg]

I have a building with a wall that faces south. The mortar between the bricks seem to be wearing away, especialy under and around the windows.
What are my choices to repair the wall? I have seen other get contractors to put up a styrofoam type of insulation on the wall and then plastering the foam board. Is this a good ( and cheap ) solution? What other choices do I have?

 

[SPQR]

Before you do that have you confirmed that the wearing away hasn't been caused by trapped moisture or water?

Because of the location of the wearing away, it could pontentially be some type of water pooling in and around the windows.

So although the foam may work it could only be short term stop gap measure.