Seal all the edges penetrations and seams.
Attic knee wall sheathing.
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.
Sheathe the kneewall during framing for new construction.
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.
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.
It is recommended that insulation be encapsulated on all six sides with a rigid air barrier like sheathing or foam board.
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.
This helps keep the supply air coming into the room nice and warm.
The traditional approach is to insulate the kneewall and the attic floor behind the kneewall.
There are two ways to block off this air flow.
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.
There is bare insulation just hanging between the 2x4 s so an air barrier looks to be needed.
There are two ways to insulate triangular attics behind kneewalls.
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.
Sometimes though there are no soffits.
Cover the whole wall.
Cover the whole wall.
A leaky kneewall also can provide a pathway for escaping warm air to heat up roof sheathing which can contribute to ice dams.
Ventilating knee wall attics is challenging.
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.
So companies like norbord started creating tallwall windstorm panels to help alleviate this.
Here are the three keys to sheathing an attic kneewall properly.
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.
Old school roof vents which look like rectangles on the roof work pretty well too.
