What can be damaging the bricks and mortar on the outside of my house?

It could be something called spalling,that is where over a period of years the outside face of the brick starts to detach from the rest of it,and is more apparent when we have a cold winter as frost gets in behind the weakened face of the brick and forces it off.If it is very bad then you have to rake out the mortar joints and replace the bricks(its quite easy)the only problem can be getting bricks too match.The same problem could be said of the mortar.