Top corners and returns need appropriate ordinary cutting and fitting. Show any unusual junctions before ordering material. A compatible profile and adequate lengths matter; filling large mismatches is not equivalent to a properly planned replacement surround.
Width, thickness and shape affect how the new surround meets the opening and nearby trim. Supply the proposed profile rather than relying on a distant photograph. This is decorative architrave replacement, distinct from repairing the door jamb or load-bearing parts of an opening.
Agree filling, joint preparation and the painting boundary. A primed replacement can still need final decoration after fitting. Window glazing, specialist seals and rated-door certification are outside the task even where the new architrave sits beside those systems.
Replace the accepted ordinary decorative surround with suitable joints and fixings, leaving the agreed preparation for finishing. Scope limits: Ordinary decorative surrounds only. No structural jamb or opening modifications, specialist glazing, fire-door certification or hazardous-material disturbance.