Attic Knee Wall Sheathing

Seal all the edges penetrations and seams.

Attic knee wall sheathing. The airflow in the ducts suffers from friction losses and the air loses heat to the cold attic space as it makes its way to the room. So companies like norbord started creating tallwall windstorm panels to help alleviate this. Cover the whole wall. The traditional approach is to insulate the kneewall and the attic floor behind the kneewall.

Cover the whole wall. In an ideal world we install soffit vents as intakes make sure the slopes can breathe with ventilation baffles and exhaust through a ridge vent. On one wall that is partially exposed to the outside but mainly in the attic the original builder used fiberboard. It is recommended that insulation be encapsulated on all six sides with a rigid air barrier like sheathing or foam board.

Ventilating knee wall attics is challenging. Here are the three keys to sheathing an attic kneewall properly. There is bare insulation just hanging between the 2x4 s so an air barrier looks to be needed. Seal all the edges penetrations and seams.

We live in a cape cod style home and i d like to install an air barrier on the second floor knee walls. The death of the 8 sheet one of the biggest items when sheathing a wall vertically is that the sheathing has to be continuous 602 10 4 5 which meant that an 8 sheet wouldn t cut it in many places so longer ones were required. There are two ways to insulate triangular attics behind kneewalls. Sheathe the kneewall during framing.

Old school roof vents which look like rectangles on the roof work pretty well too. The best way to handle a knee wall area is to move the thermal barrier to the roofline left and stand up the knee walls after the ceiling has been drywalled. There are two ways to block off this air flow. This helps keep the supply air coming into the room nice and warm.

So after we seal up the insulated air barrier for the bonus room knee wall we install a thick blanket of cellulose insulation around the duct. Sometimes though there are no soffits. Radiant barrier wall sheathing can be attached to the attic exterior side of a knee wall to cut down on radiant heat gain or heat loss in the winter. For production builders who may have less control in scheduling trade partners the knee wall can serve as the thermal barrier right as long as sheathing is installed on the back side.

Here are the three keys to sheathing an attic kneewall properly.