4.1004.1 Preparation for Dense Packing

Topic:

Attics

Subtopic:

Knee Walls

Desired Outcome:

Airtight cavity and insulated knee wall Knee wall Any wall between the conditioned space and the attic

For supporting material, see Calculation of the Infiltration Credit, General Information on Spray Polyurethane Foam (SPF), Referenced Standards and Building America Solution Center.

Single-Family Homes

	Title	Specification(s)	Objective(s)
	4.1004.1a Backing	All knee walls will have top and bottom plate or blockers installed using rigid materials 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 If fabric is used before dense packing, it will be secured, according to manufacturers specifications or with furring strips every wall stud 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 accessible knee wall Knee wall Any wall between the conditioned space and the attic area If foam sheathing is used, sheathing will be listed for uncovered use in an attic or covered with a fire barrier	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 Ensure material will not tear under stress from wind loads or insulation
	4.1004.1b Installation	All existing batted insulation will be adjusted to ensure it is in full contact with the interior cladding and the top and bottom plates Insulation that is blown behind fabric or 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 material will be blown dense to a minimum specification of 3.5 pounds per cubic foot for cellulose Follow manufacturer's requirements for fiberglass dense pack Dense pack The process of installing loose-fill insulation to reduce air flow and perform to a stated R-value applications	Eliminate misalignment of existing insulation Prevent insulation from settling or moving

Title

Specification(s)

Objective(s)

4.1004.1a
Backing

All knee walls will have top and bottom plate or blockers installed using rigid materials

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

If fabric is used before dense packing, it will be secured, according to manufacturers specifications or with furring strips every wall stud

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 accessible knee wall Knee wall Any wall between the conditioned space and the attic area

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

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

Ensure material will not tear under stress from wind loads or insulation

4.1004.1b
Installation

All existing batted insulation will be adjusted to ensure it is in full contact with the interior cladding and the top and bottom plates

Insulation that is blown behind fabric or 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 material will be blown dense to a minimum specification of 3.5 pounds per cubic foot for cellulose

Follow manufacturer's requirements for fiberglass dense pack Dense pack The process of installing loose-fill insulation to reduce air flow and perform to a stated R-value applications

Eliminate misalignment of existing insulation

Prevent insulation from settling or moving