US Patent 10472882 Modular sub-sill unit

A modular sub-sill unit to provide improved water drainage is attachable to a bottom part of a sill and to a portion of an exterior wall that corresponds to the bottom of an opening, such as a door, window, or skylight. The sub-sill unit may include a top plate, which provides a plurality of weep holes that allow liquid to pass through and be deposited on an inner deflection wall. The inner deflection wall deflects the liquid into a water trough or channel, which extends across the length of the sub-sill unit at a front edge facing outwardly from the exterior wall. The liquid then exits through a plurality of exit holes in the outer front edge. The inner deflection wall thus creates a dry zone that prevents the liquid from reaching a base plate and protects the fasteners that attach the base plate to the exterior wall.