Attic Knee Wall

An attic knee wall is a short wall that extends from the floor of an attic room to the roof rafters.

Attic knee wall.

The doors can be installed in two versions of opening right or left. But you do so at the expense of floor space. Doing this is just one step in finishing off an attic to make it a useful space and it helps to insulate your attic space against air infiltration from the outside. There are two ways to block off this air flow.

Knee walls are short usually wooden walls installed around the sides of an attic where the rafters meet the floor. The 2 5 8 thick sash fully filled with thermo insulating material provides an excellent barrier reducing heat loss r value 9 5. A reader asks if i need to install a knee wall in my attic but what is the purpose of a knee wall. Knee walls are the short interior walls built beneath the roof rafters.

The problem with many kneewalls is that they have fiberglass batt insulation with nothing covering them on the attic side as shown in the photo below. In the photo at left the kneewall is the short wall with the door in it. Not every home has knee walls. The knee wall forms the wall of the attic room and it also creates an enclosed space under the eaves behind the wall.

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. These low walls help define the living space by creating vertical surfaces between the sloping rafters and the finished floor. The doors as standard are equipped with handle and finishing lining. Knee walls are not found in all attics.

They re most often found in finished attics and top floor living spaces. 1 a continuous air barrier can be installed on the exterior of the kneewall framing from the top of the knee wall down to the attic floor including the spaces between the attic floor joists from the bottom of the knee wall to the ceiling deck below or 2 a continuous air barrier can be installed along the underside of the attic roofline from the top of the knee wall to the top plate of the home s exterior wall. 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.

A knee wall is a short vertical wall roughly two or three feet high that blocks in that useless triangular space. The dwt knee wall access doors are new and highly energy efficient design. The higher the knee wall the greater the amount of useful wall space you create in your finished attic. If you aren t sure whether or not your attic contains knee walls go and look around the edges.

What are knee walls.