composite sill

composite sill

[kəm′päz·ət ′sil]
(geology)
A sill consisting of several intrusions differing in chemical and mineralogical compositions.
References in periodicals archive ?
Several manufacturers also have tackled a problem area by incorporating composite sill systems into entry doors, preventing-water from wicking up into the door frame.
Campbell says he's seeing increasingly more use of composite parts in windows, such as composite sills, and that this is where the growth is.