A channel assembly for framing a doorway includes a primary frame element having adjacent inside and outside channel sections respectively provided with trim sections adapted to overlie inside and outside walls. A separate door stop member includes hook elements engageable with catch devices integral with one such channel section to permit removable attachment of the stop member. Hinge and strike provisions are achieved through a separate plate also having hook elements and which are snap-fittedly engageable with catch devices integral with the inside channel section such that any of various customized hinge and strike provisions may be provided with any one frame element. The frame element may comprise a unitary member for installation with a fixed wall thickness or, separate inside and outside channel sections slidably overlapping one another to permit accommodation of varying wall thicknesses. In either instance, trim sections normal to the ends of the frame element provide a finish trim overlying the wallboards and this trim may comprise and integral portion of the frame element or include separate, snap-on members.