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A knee wall is a short
A knee wall is a short wall
A wall is a structure and a surface that defines an area; carries a load; provides security, shelter, or soundproofing; or, is decorative. There are many kinds of walls, including:
* Walls in buildings that form a fundamental part of the supe ...
, typically under three feet (one metre) in height, used to support the rafter
A rafter is one of a series of sloped structural members such as wooden beams that extend from the ridge or hip to the wall plate, downslope perimeter or eave, and that are designed to support the roof shingles, roof deck and its associated ...
s 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
A ridge or a mountain ridge is a geographical feature consisting of a chain of mountains or hills that form a continuous elevated crest for an extended distance. The sides of the ridge slope away from the narrow top on either side. The line ...
to the eaves
The eaves are the edges of the roof which overhang the face of a wall and, normally, project beyond the side of a building. The eaves form an overhang to throw water clear of the walls and may be highly decorated as part of an architectural styl ...
. 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.
The term is derived from the association with a human knee, partly bent. Knee walls are common in houses in which the ceiling on the top floor is an attic
An attic (sometimes referred to as a '' loft'') is a space found directly below the pitched roof of a house or other building; an attic may also be called a ''sky parlor'' or a garret. Because attics fill the space between the ceiling of the ...
, i.e. the ceiling is the underside of the roof and slopes down on one or more sides.
Jamb height
Since there is no legal definition of the jamb height, further specifications are required as to how it is to be measured. It is generally accepted that the knee wall begins at the upper edge of the soffit of the floor below. There is no uniform use of the term for the end of the knee stick. In the greatest extent of the knee wall, this extends to the imaginary intersection of the outer wall with the upper edge of the rafter. The smallest dimension is when the knee wall is understood to mean only the wall that goes beyond the attic ceiling (excluding the base purlin). Between these possibilities, other methods of measurement are in use.See also
*Sleeper wall
A sleeper wall may refer to the following types of walls:
*sleeper wall is a short wall used to support floor joists, beam and block or hollowcore slabs at ground floor. It is constructed in this fashion when a suspended floor(Also called suspen ...
– a short wall used to support floor joists of a ground floor
References
Types of wall Building engineering {{Architecturalelement-stub