Roof Support Knee Wall

This article describes and illustrates the different types of support that prevents roof sagging and wall bulging at buildings including definitions of collar ties rafter ties and structural ridge beams.

Roof support knee wall.

Purlins as shown in sample photos below are installed for rafter support. In most instances they are no taller than 3 feet but some builders may custom fit them according to the roof s shape and size. You can see the image below for an example of a knee wall. Homeowners cannot take chances with the structural integrity of their roofs.

The knee wall forms the wall of the attic room and it also creates an enclosed space under the eaves behind the wall. The roof is subject to pressure placed on it by natural forces including snow rain. Check that the 2 by 4 is plumb with a spirit level. Knee walls are short usually wooden walls installed around the sides of an attic where the rafters meet the floor.

An important notation is that the purlin bracing should be off of walls or beams as needed. In his book a visual dictionary of architecture francis d. 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. 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.

Hold up to the rafter a scrap piece of 2 by 4 lumber a few inches longer than the planned knee wall height with its base on the floor. Collar ties rafter ties tension beams structural ridge beams. Sometimes commonly referred to as a corbel support or knee brace support versions of this bracket are routinely used on contemporary homes as a support for countertop overhangs shelves mantels or anywhere a cantilevered shelf or eave needs support or aesthetic enhancement. Add craftsman brackets to your home even it s not craftsman style if it has overhanging exposed eaves.

A knee wall is a short wall typically under three feet one metre in height used to support the rafters in timber roof construction.