PSUengineer1:
I agree with Hokie. Some of this has already been said or implied above, and I might just be saying it in slightly different words. The crack pattern shows how it is working now, not necessarily how it was designed. If the sliding door is working well, the lintel most likely is not the problem. What you really meant to say is the brick tends to act in an arching fashion over a lintel, with any lintel deflection and the cracking pattern shows that. But for the arching action to really work correctly and not cause the cracking you see, there must be a strong ability to impart arch supporting inward thrusts at the spring line of the arch (the head of the door opening elev.). The brick plane (or panel) on the left of the opening is stronger (stiffer) in this respect, than the shorter plane of the right. So, these thrusts tend to push things to the right. Then, you have the fact that brick is a naturally expansive material with age, and the more so with any water getting into the brick from (around) the window opening above. You could also have some thermal expansion, again pushing to the right due to that area being the weaker reaction plane. Finally, there could be some found. movement on the right corner. It is really good/helpful if you can watch these kinds of problems over a year’s worth of seasons, and if you can see them develop, rather than having them so well developed, that you are to late to see what caused what.