Architectural detailing assembly method and apparatus

An architectural detailing assembly ( 10 ) and a method of forming an architectural detailing assembly. The architectural detailing assembly includes an architectural detailing ( 12 or 14 ) having a length terminating in an end surface ( 22 ), and an appearance surface ( 28 ) adapted to be viewed by a user once installed upon a building structure and having a predetermined profile. The architectural detailing also includes a spacer ( 16 ) having a first planar wall ( 38 ) adapted to be selectively coupled to the end surface of the architectural detailing and a second planar wall ( 40 ) oriented substantially parallel with the first planar wall and separated from the first planar wall by a thickness. The spacer includes a sealant backing surface ( 45 ) oriented substantially perpendicular to and extending between the first and second planar walls. The sealant backing surface is shaped to substantially have the predetermined profile.