knee wall
a partition for supporting roof rafters when the span is great or for forming a side wall (as of a second-story room) under a pitched roof
Knee wall Definition & Meaning - Merriam-Webster)
When to Install a Knee Wall in Your AtticA knee wall is a short wall, typically under three feet (one metre) in height, used to support the rafters in timber roof construction. In his book A Visual Dictionary of Architecture, Francis D. K. Ching defines a knee wall as "a short wall supporting rafters at some intermediate position along their length." The knee wall provides support to rafters which therefore need not be large enough to span from the ridge to the eaves. Typically the knee wall is covered with plaster or gypsum board, enclosing the useful part of the attic space (not necessarily high enough for a person to stand up), while the remaining small space under the eaves is only useful for storage.
Knee wall - WikipediaAls Kniestock (oder auch Drempel beziehungsweise Trempel) bezeichnet man die an der Traufseite eines Hauses über die Rohdecke des letzten Obergeschosses hinaus gemauerte Außenwand, auf der die Dachkonstruktion aufliegt. Er ist ein typisches Merkmal von Pfettendächern.
Kniestock – Wikipedia