A corner block is a square piece of wood placed in the corner of horizontal and vertical trim bits on a window or door. It may be plain or carved with an intricate design, and it makes the job of fitting the casing easy, because only directly finish cuts are demanded. (The casing is the trim that covers the seams in which door jambs, windows or wall openings are placed.)
Mason Construction Company
This corner block is easy to see. The unpainted, square wood block at the corner has a circle detail carved in it. The casing is painted white and has fluted details carved in it that seem like grooves.
Shannon Malone
At the turn of this century, corner cubes were employed as a decorative element. They were carved with bull-eyes, flowers, rosettes, stars, shellfish or ripples.
Round Here Renovations
Corner cubes are used on the bedroom’s casings.
Patricia Horton
Casings replaced post and lintel construction, which was made up of large visible squared timbers that supported door and window openings. When stud walls began to be sheathed in plaster, then casing turned into a necessary trim.
Round Here Renovations
Corner cubes simplify casing installation, because just straight cuts and dimensions are necessary for the horizontal and vertical boards.
Without a corner block, the casing matches in the corner in a 45-degree angle. Angled cuts need mitering; they are more challenging to align and may be less exact.
SC Homes
At times the detail of this corner block is repeated in the plinth, that’s the foundation of the door casing.
Shannon Malone
Using glue and a pneumatic nailer is the simplest way to install a corner block. This original corner block at the top left adorns a space with raised panel doors and a fluted casing.
More: Rosette Blocks Show It’s Hip to Be Square
