Attic Knee Wall Air Barrier

They are 2 4 construction kraft faced r 11 batts in the wall with the paper facing the drywall and a plastic vapor barrier in the knee wall attic.

Attic knee wall air barrier. Rigid air barrier material could include rigid foam insulation drywall plywood or osb among others. Attic knee walls are typically short vertical walls approximately 2 to 3 feet high in an attic that separates attic space from conditioned space. Although drywall may work as a sufficient air barrier if not penetrated knee walls can suffer from insufficient air barriers. Fit it flush against the vent and first floor top plate and foam seal around it.

Explanation offered in the video is that. Housewrap can be an adequate air barrier too and is easier to get into tight kneewall spaces. Knee walls and bonus room air seal issues duration. The bottom plate of the knee wall rests on top of the floor joists leaving a large pathway for attic air to come up into the air cavity of the knee wall.

Proper air barrier installed on kneewall. First the sealing of the joints of the rigid material or house wrap on the attic side of the knee wall surface is not needed if and i strongly state if the knee wall has been throughly air sealed. Most common attic knee walls are associated with the creation of a bonus room that can have many uses. Assuming styrofoam vent chutes are installed rough cut a foam block to fit between the rafters.

That has the potential to degrade the insulation as convective air loops through the insulation now i m wondering if the approach i was thinking of using is flawed and needs to be adjusted. First you will want to add traditional insulation between the studs this can be batt insulation spray foam or even rigid foam insulation. If i place vertical runs of r 30 unfaced against the current plastic barrier i d use a perforated. Air leakage is at the pressure barrier which is before the thermal barrier.

Install a continuous air barrier on the exterior side of the attic knee wall framing with a rigid air barrier or other supporting material to prevent the knee wall cavity insulation from sagging and to create a continuous thermal barrier. Without a little help 2 gable vents on each side of a knee wall attic won t move much air. Fiberboard is just fine as an air barrier in that application. Knee walls that share space with a conditioned room in your home should have a combination of both traditional insulation and foil radiant barrier insulation.

Just be sure to air seal it to the framing and make sure that any seams between sheets of housewrap occur at framing members not between studs taped with housewrap tape. The first point is sealing the soffit venting. Air sealing the attic.