If your flooring runs parallel with the door you ll likely have only one piece of laminate to trim.
Laminate under door trim.
Using a framing square measure the depth of your door jamb by sliding the square under the newly cut gap until the tool hits the door frame or stud.
You can deal with door jambs by trimming the molding that conceals the.
I made a quick video on how to undercut door jambs for laminate flooring it is a diy job most people could undertake themselves if the have some basic tools.
The 1 2 inch gap is for the doorway only.
If there s a gap under your door casing and also a gap between two rooms under a door where two different installations of laminate flooring join you can install t molding to hide both gaps.
Measure on the inner jamb as well as both sides of the door where the trim is located.