You can use a butt joint or a miter joint for the outside corner. Our recommendation is the butt joint because most installers find it easier.
Butt Joint : You will need to add 5/8" to the panel that is going to overlap. You might also want to compensate the stile width by 5/8" so that the finished end stile will be the same on both panels.
Miter Joint 90° corner: You will need to add 5/8" to both panels and cut the 45 degree miter angle at time of installation.
