Designing Buildings - User contributions [en]

Knee wall

2021-11-17T21:16:57Z

Measurite:

A knee wall is a short [https://en.wikipedia.org/wiki/Wall wall], typically under three feet (one metre) in height, used to support the [https://en.wikipedia.org/wiki/Rafter rafters] in timber roof construction. In his book A Visual Dictionary of Architecture, [https://en.wikipedia.org/wiki/Frank_Ching Francis D. K. Ching] defines a knee wall as "a short wall supporting rafters at some intermediate position along their length."[https://en.wikipedia.org/wiki/Knee_wall#cite_note-1 [1]] The knee wall provides support to rafters which therefore need not be large enough to span from the [https://en.wikipedia.org/wiki/Ridge ridge] to the [https://en.wikipedia.org/wiki/Eaves 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.

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 [https://en.wikipedia.org/wiki/Attic attic], i.e. the ceiling is the underside of the roof and slopes down on one or more sides.

See the following link [https://en.wikipedia.org/wiki/Knee_wall https://en.wikipedia.org/wiki/Knee_wall]

In Ontario Canada, the Ontario Building Code also includes dwarf wall in place of knee wall for the same function. The following excerpt is from the OBC 2012 rev 7 effective Jan 1 2021

Rule 9_23_13_7. Intermediate Support For Rafters And Joists

(1) Ceiling joists and collar ties of not less than 38 mm by 89 mm lumber are permitted to be assumed to provide intermediate support to reduce the span for rafters and joists where the roof slope is 1 in 3 or greater.

(2) Collar ties referred to in Sentence (1) more than 2.4 m long shall be laterally supported near their centres by not less than 19 mm by 89 mm continuous members at right angles to the collar ties.

(3) Dwarf walls and struts may be used to provide intermediate support to reduce the span for rafters and joists.

(4) When struts are used to provide intermediate support, they shall be not less than 38 mm by 89 mm material extending from each rafter to a loadbearing wall at an angle of not less than 45° to the horizontal.

(5) When dwarf walls are used for rafter support, they shall be framed in the same manner as loadbearing walls and securely fastened top and bottom to the roof and ceiling framing to prevent overall movement.

(6) Solid blocking shall be installed between floor joists beneath dwarf walls referred to in Sentence (5) that enclose finished rooms.

[[Category:Definitions]]

Knee wall

2021-11-17T21:16:11Z

Measurite:

A knee wall is a short [https://en.wikipedia.org/wiki/Wall wall], typically under three feet (one metre) in height, used to support the [https://en.wikipedia.org/wiki/Rafter rafters] in timber roof construction. In his book A Visual Dictionary of Architecture, [https://en.wikipedia.org/wiki/Frank_Ching Francis D. K. Ching] defines a knee wall as "a short wall supporting rafters at some intermediate position along their length."[https://en.wikipedia.org/wiki/Knee_wall#cite_note-1 [1]] The knee wall provides support to rafters which therefore need not be large enough to span from the [https://en.wikipedia.org/wiki/Ridge ridge] to the [https://en.wikipedia.org/wiki/Eaves 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.

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 [https://en.wikipedia.org/wiki/Attic attic], i.e. the ceiling is the underside of the roof and slopes down on one or more sides.

See the following link [https://en.wikipedia.org/wiki/Knee_wall https://en.wikipedia.org/wiki/Knee_wall]

In Ontario Canada, the Ontario Building Code also includes dwarf wall in place of knee wall for the same function. The following excerpt is from the OBC 2012 rev 7 effective Jan 1 2021

Rule "9.23.13.7" Intermediate Support For Rafters And Joists

(1) Ceiling joists and collar ties of not less than 38 mm by 89 mm lumber are permitted to be assumed to provide intermediate support to reduce the span for rafters and joists where the roof slope is 1 in 3 or greater.

(2) Collar ties referred to in Sentence (1) more than 2.4 m long shall be laterally supported near their centres by not less than 19 mm by 89 mm continuous members at right angles to the collar ties.

(3) Dwarf walls and struts may be used to provide intermediate support to reduce the span for rafters and joists.

(4) When struts are used to provide intermediate support, they shall be not less than 38 mm by 89 mm material extending from each rafter to a loadbearing wall at an angle of not less than 45° to the horizontal.

(5) When dwarf walls are used for rafter support, they shall be framed in the same manner as loadbearing walls and securely fastened top and bottom to the roof and ceiling framing to prevent overall movement.

(6) Solid blocking shall be installed between floor joists beneath dwarf walls referred to in Sentence (5) that enclose finished rooms.

[[Category:Definitions]]

Knee wall

2021-11-17T21:14:44Z

Measurite:

A knee wall is a short [https://en.wikipedia.org/wiki/Wall wall], typically under three feet (one metre) in height, used to support the [https://en.wikipedia.org/wiki/Rafter rafters] in timber roof construction. In his book A Visual Dictionary of Architecture, [https://en.wikipedia.org/wiki/Frank_Ching Francis D. K. Ching] defines a knee wall as "a short wall supporting rafters at some intermediate position along their length."[https://en.wikipedia.org/wiki/Knee_wall#cite_note-1 [1]] The knee wall provides support to rafters which therefore need not be large enough to span from the [https://en.wikipedia.org/wiki/Ridge ridge] to the [https://en.wikipedia.org/wiki/Eaves 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.

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 [https://en.wikipedia.org/wiki/Attic attic], i.e. the ceiling is the underside of the roof and slopes down on one or more sides.

See the following link [https://en.wikipedia.org/wiki/Knee_wall https://en.wikipedia.org/wiki/Knee_wall]

In Ontario Canada, the Ontario Building Code also includes dwarf wall in place of knee wall for the same function. The following excerpt is from the OBC 2012 rev 7 effective Jan 1 2021

9.23.13.7. Intermediate Support For Rafters And Joists

(1) Ceiling joists and collar ties of not less than 38 mm by 89 mm lumber are permitted to be assumed to provide intermediate support to reduce the span for rafters and joists where the roof slope is 1 in 3 or greater.

(2) Collar ties referred to in Sentence (1) more than 2.4 m long shall be laterally supported near their centres by not less than 19 mm by 89 mm continuous members at right angles to the collar ties.

(3) Dwarf walls and struts may be used to provide intermediate support to reduce the span for rafters and joists.

(4) When struts are used to provide intermediate support, they shall be not less than 38 mm by 89 mm material extending from each rafter to a loadbearing wall at an angle of not less than 45° to the horizontal.

(5) When dwarf walls are used for rafter support, they shall be framed in the same manner as loadbearing walls and securely fastened top and bottom to the roof and ceiling framing to prevent overall movement.

(6) Solid blocking shall be installed between floor joists beneath dwarf walls referred to in Sentence (5) that enclose finished rooms.

[[Category:Definitions]]

Knee wall

2021-11-17T21:06:03Z

Measurite: Created page with "A knee wall is a short [https://en.wikipedia.org/wiki/Wall wall], typically under three feet (one metre) in height, used to support the [https://en.wikipedia.org/wiki/Rafter raft..."