The visible reveal between trim and frame needs an agreed consistent position. Existing irregularities can affect the result. Replacing decorative material does not authorise reshaping the structural opening or hiding a frame condition that needs separate repair.
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.
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.