Knee Wall Roof Supports

Purlins as shown in sample photos below are installed for rafter support.

Knee wall roof supports.

A knee wall is a short wall typically under three feet one metre in height used to support the rafters in timber roof construction. An important notation is that the purlin bracing should be off of walls or beams as needed. If you have existing brackets use one for reference. The braces struts or kickers should be within every 4 and should not be at a greater than a 45 degree angle towards the roof slope lower side.

Measure the eave overhang from the exterior wall and add 5 inches to the measurement to provide a reveal or extension on the end of the horizontal beam that supports the eave if desired but you can cut it longer or shorter. The out of plane loads are transferred to the floor system through a thick plate nested in the flanges of the member with two diameter fasteners or one diameter fastener for 250mw used for the connection. In his book a visual dictionary of architecture francis d. Knee walls are short usually wooden walls installed around the sides of an attic where the rafters meet the floor.

Use pressure treated 4 by 4 beams to build a basic craftsman bracket. 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. Unlike other kinds of knee walls this kind of wall extends all the way to the rafters but because of the slope of the roof it is shorter than a full height wall. Midwall is designed to support out of plane loading in cantilevered partial wall systems that are unsupported at the top track.

How to stabilize a knee wall. Knee walls are most commonly seen in bathroom settings where they separate a toilet niche from a countertop or provide a small separation between a vanity and a shower.