Foam Board Attic Knee Wall

You ll need to air seal all the penetrations and leaky spots like joists under the kneewall.

Foam board attic knee wall.

Replace foam into the board and then tape with homesealr. This is not very easy in most of the older houses we work on because the hatches and attics are too small to get rigid foam board through. 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. The best way to provide that sheathing is to use a rigid material.

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. 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. 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. 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. 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.

When installing foam insulation boards in the attic make sure you start from one corner and work your way around the room. This method of insulation won t work if the triangular attic includes ducts or plumbing pipes. This method has you place the foil closest to the inside of the wall cavity with an air gap. One of the best methods is rigid foam board with sealed joints over insulation in the knee wall.

There are as many ways to do it as there are people who do it. Boards may be used vertically or horizontally to minimize cuts.