I'm considering installing a skylight in my living room that would require a rather large 4'x7' opening in the ceiling. I'm concerned about how to frame the opening in the ceiling because it is flat drywall, with an attic above, and it would require cutting several ceiling joists along the length of the opening in order to frame a lightshaft. The two ceiling joists at the ends it seems would have to support a pretty big load and I am unsure about how to go about reinforcing them or making sure that the ceiling has enough support.