Explanation offered in the video is that.
Attic knee wall air barrier.
Fit it flush against the vent and first floor top plate and foam seal around it.
Attic knee walls are typically short vertical walls approximately 2 to 3 feet high in an attic that separates attic space from conditioned space.
Housewrap can be an adequate air barrier too and is easier to get into tight kneewall spaces.
Fiberboard is just fine as an air barrier in that application.
The insulation in the knee walls of an attic is usually uncovered on the attic side.
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.
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.
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.
Without a little help 2 gable vents on each side of a knee wall attic won t move much air.
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.
Air sealing the attic.
Then you can add atticfoil on top of the traditional insulation by stapling it to the wall studs.
Assuming styrofoam vent chutes are installed rough cut a foam block to fit between the rafters.
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.
Rigid air barrier material could include rigid foam insulation drywall plywood or osb among others.
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.
If i place vertical runs of r 30 unfaced against the current plastic barrier i d use a perforated.
First you will want to add traditional insulation between the studs this can be batt insulation spray foam or even rigid foam insulation.
Most common attic knee walls are associated with the creation of a bonus room that can have many uses.
Knee walls and bonus room air seal issues duration.
Air leakage is at the pressure barrier which is before the thermal barrier.
The ceiling and knee wall drywall will act as your air barrier.
