4.1004.2 Preparation for Batt Insulation

Topic: 
Attics
Subtopic: 
Knee Walls
For supporting material, see Building America Solution Center.
Desired Outcome: 
Airtight cavity and properly insulated knee wall Knee wall Any wall between the conditioned space and the attic
TitleSpecification(s)Objective(s)
4.1004.2a
Knee wall Knee wall Any wall between the conditioned space and the attic prep for batts

 All knee walls will have a top and bottom plate or blockers installed using a Rigid material Rigid material Drywall, oriented strand board, duct board, cardboard, or any other stiff product that may support the load of insulation while serving as a durable air barrier

All joints, cracks, and penetrations will be sealed in finished material, including interior surface to framing connections 

When knee wall Knee wall Any wall between the conditioned space and the attic floor and walls are being insulated, the floor joist running under the knee wall Knee wall Any wall between the conditioned space and the attic will be air sealed.
 

Eliminate bending, sagging, or movement that may result in air leakage

Prevent air leakage through the top or bottom of the knee wall Knee wall Any wall between the conditioned space and the attic

Create an air barrier Air barrier The separation between the interior and exterior environments of a building that slows air flow to the point that no smoke movement is visible at 50 pascals of pressure difference across the boundary

4.1004.2b
Installation

Insulation will be installed using one of the following methods:

  • New batts will be installed in accordance with manufacture specifications
  • All existing batted insulation will be adjusted to ensure it is in full contact with the interior cladding and the top and bottom plates

Eliminate misalignment of existing insulation

4.1004.2c
Backing knee wall Knee wall Any wall between the conditioned space and the attic

If rigid material Rigid material Drywall, oriented strand board, duct board, cardboard, or any other stiff product that may support the load of insulation while serving as a durable air barrier is used, material will be installed to cover 100% of the surface of the knee wall Knee wall Any wall between the conditioned space and the attic

If foam sheathing is used, sheathing will be listed for uncovered use in attic, or covered with a fire barrier

Prevent insulation from settling or moving