Trim for Shim Doctrine

This doctrine in house construction is a concept of using the straightness or alignment of trim or trim assemblies to facilitate alignment or trimming tasks in the post-structural framing phases of house construction. The general concept is one of replacing the function which shims typically provide - by using trim instead.

When accurate trimming is required in house construction, such as house corners or door frames (such as closet) - instead of using numerous shims for truing and alignment - use trim assemblies to produce the truing or alignment that is required. Trim installation is assumed to be faster than shimming. See for example the under-stair closet door - [1]

Another part of this doctrine includes propping up the trim with a trim puller or pry bar on the back side of the trim, so that the trim does not get sucked in upon nailing or screwing. This applies in conditions of laying trim and attaching trim against non-flat walls so that the trim remains straight without waving - or otherwise retaining the straightness and alignment of trim - to cover up non-straightness or non-alignment of rough framing.

For finishing work, trim may be deliberately evened out with a trim puller, with gaps subsequently filled or caulked. This creates a straight finish upon painting, even if the underlying structure is not straight, flat, or otherwise aligned.

This is part of a more general doctrine of Design-for-Tolerancing.