Many window openings in New Orleans are out of square. The most economical fix is to modify the window to the sill. This issue can sometimes present as a dropped upper sash that has been caulked in place. This requires removal of the upper sash, then cutting the top rail to the slope of the header.

In this example, the previous owner had filled the void with caulk. My client simply wanted the window to function. In order to make this happen, and allow the window to seal when closed, I added wood to the bottom rail before cutting it to the slope of the sill. It looks a little funky, but is perfectly functional.