Foam Board Attic Knee Wall

Foam insulation boards can be attached to concrete walls as well and in such a case care should be taken not to chip the cement.

Foam board attic knee wall. Start at left or right side to install the first board using cap. An insulated kneewall is effectively an exterior wall so you ll need a layer of rigid foam drywall osb or thermoply on the back side of the kneewall to prevent cold air from degrading the performance of the insulation. There are as many ways to do it as there are people who do it. You can use foam board to make baffles near your soffit vents and then blow in enough insulation to reach the r value you want.

Cut boards to snugly fit from bottom to top of wall. Another way to install the radiant barrier on a knee wall is to do so via the cathedral ceiling method. I ve also seen attic kneewalls sheathed with non rigid materials mainly housewrap. I ve seen osb oriented strand board the flaky plywood foamboard and structural or non structural cardboard sheathing materials like thermo ply.

Using foam spacers you can attach the foil behind the drywall and then stuff the remainder of the wall cavity with traditional insulation or foam board. Replace foam into the board and then tape with homesealr. The best way to provide that sheathing is to use a rigid material. This method has you place the foil closest to the inside of the wall cavity with an air gap.

You ll need to air seal all the penetrations and leaky spots like joists under the kneewall. When installing foam insulation boards in the attic make sure you start from one corner and work your way around the room. Then you will leave the wall exposed to the attic so the radiant barrier is facing an air space the attic air space. If you want the attic to be outside then using foamboard on the attic side of the knee wall is a good idea.

Attic knee wall gable ends. Boards may be used vertically or horizontally to minimize cuts.