 Custom weatherstripping, compared to pre-weatherstripped units, requires much more time and is considered to be a specialized skill.Weatherstrippers install a threshold, cut the door and install a sweep or J-hook to the bottom of the door, and nail spring-steel bronze into the doorjamb to seal the gap.Door weatherstripping is critical for thermal comfort and the overall energy efficiency of any building, particularly in Zero Energy and Passive House building projects for cold climates.