I'm looking for some answers to a problem I just encountered. I was finishing out a staircase where the general contractor had specified and supplied material. I had many problems with wood movement on this project, but one in particular baffled me. I was using 1 1/4" x 11" pine for skirt boards. These were applied to the outside of the stairs and cut to fit tight between fir posts. After a couple of days almost all of the joints had opened at the heel of the plumb cut making it appear as if the angle was miscut. The posts themselves had had some earlier twisting problems, but all the rail joints that I cut to them remained tight, so I can't attribute the problem to their further movement. The pine skirtboards had been stained on both sides prior to my working with them. It just seemed odd to me that they all pulled away at the heel of the cut. Anybody got any answers for this?