We are remodeling our bathroom. We completely gutted it and redid the plumbing for a new shower base with fiber glass walls. When we put up the ceiling, (we used the MS board, it was purple) we noticed that we had left a half inch gap between the wall beams and the MS board on one side, meaning it was not flush against the wall beams. What can we do to remediate this? Should we take the board down and redo it or is there something that we can use to fill the gap?