Butting Thicker Trim to Thinner Casing
A closer look at three ways to butt up a thicker trim to a thinner casing.
1) Butt Joint (above) The Butt Joint is used when the Vertical trim is Wider than the Horizontal trim. The Butt joint is made using a simple straight cut on the horizontal trim and is joined to, or Butted up against the wider vertical trim. In the event that your existing casing is not thick enough, you have the option of changing the casing or of adding a "back band" on top of the existing casing as shown above.
2) Beveling Back (above) Beveling is used when the horizontal trim is thicker than the vertical trim. You should bevel the larger trim back on an angle, usually 45 degrees, in order to meet the thickness of the narrower trim. This gives it a cleaner appearance and does not leave a sharp corner.
3) Return (above and below) The Return is made using a miter cut on the horizontal trim and cutting out a separate "Pie" piece to fill in the gap and attach it to the wall. The Return is an excellent option when you are finishing on a wall or opening with no trim or when your horizontal trim is thicker than your vertical trim.