Installing Door and Window Trim
One common problem when trimming a window or door is the jamb of the door or window does not come out flush with the interior wall. This causes the trim to rock. Below is a simple tip for installing door casing.
In many of these cases it is necessary to install “extension jambs.” An extension jamb is a thin strip of wood that makes p the difference between the door jamb and the wallboard. Think of it as a shim to make both surfaces even out.
If the space between the jamb and wall material is small, say 3/16″ of less, you can use this tip with great success.
Tip for installing Door Casing : Flatten drywall
Use your hammer to bang down or crunch the Sheetrock down next to the jamb. Be careful as to not damage the Sheetrock out past the trim width. [i.e., what your trim will cover.]