BASC Search | Building America Solution Center

Conceptual insulation at cape-style roof - ceiling and knee wall cavity insulation

Conceptual insulation at cape-style roof - ceiling and knee wall cavity insulation

CAD File

Right – The knee wall is properly insulated and air sealed.

Right – The knee wall is properly insulated and air sealed.

Image

Install an air barrier on the exterior of attic knee wall insulation.

Install an air barrier on the exterior of attic knee wall insulation.

Image

Right – The backing on this knee wall was air sealed prior to insulation.

Right – The backing on this knee wall was air sealed prior to insulation.

Image

Spray foam insulates and air seals the underside of the attic roof and walls.

Spray foam insulates and air seals the underside of the attic roof and walls.

Image

Right – Rigid backing was installed prior to insulating the attic knee walls.

Right – Rigid backing was installed prior to insulating the attic knee walls.

Image

Wrong – The backing on this knee wall was not air sealed prior to adding insulation.

Wrong – The backing on this knee wall was not air sealed prior to adding insulation.

Image

Raised heel energy trusses extend past the exterior wall and are deeper at the wall allowing room for full insulation coverage over the top plate of the exterior walls.

Image

Right – Spray foam air seals and insulates the walls including the walls behind the fireplace and covers the underside of the roof deck of this mixed-dry climate home to provide an insulated attic space for HVAC ducts.

Right – Spray foam air seals and insulates the walls including the walls behind the fireplace and covers the underside of the roof deck of this mixed-dry climate home to provide an insulated attic space for HVAC ducts.

Image

Right - The wall top plates are sealed with foam before installing insulation on the ceiling deck

Right - The wall top plates are sealed with foam before installing insulation on the ceiling deck.

Image

Right - Spray foam insulation air-seals the ceiling-to-drywall seams at the wall top plate.

Image

Right - Spray foam insulation has been sprayed onto the underside of the sloped roof and the gable end wall to provide a sealed, insulated attic for housing the HVAC ducts

Right - Spray foam insulation has been sprayed onto the underside of the sloped roof and the gable end wall to provide a sealed, insulated attic for housing the HVAC ducts

Image

Design the roof with raised heel trusses to allow full insulation over the top plates of the exterior walls.

Design the roof with raised heel trusses to allow full insulation over the top plates of the exterior walls.

Image

Spray foam insulation was installed on the underside of the roof deck and on gable end attic walls to create an unvented attic

Spray foam insulation was installed on the underside of the roof deck and on gable end attic walls to create an unvented attic

Image

In cathedral ceilings, parallel chord trusses allow thicker insulation levels over the exterior wall top plates.

In cathedral ceilings, parallel chord trusses allow thicker insulation levels over the exterior wall top plates.

Image

Standard roof trusses are narrow at the eaves, preventing full insulation coverage over the top plate of the exterior walls

Image

Right – This attic knee wall and the floor joist cavity openings beneath it are being sealed and insulated with spray foam.

Right – This attic knee wall and the floor joist cavity openings beneath it are being sealed and insulated with spray foam.

Image

Wrong: open wall cavity connected to this return air plenum is allowing cellulose attic insulation to be pulled into the furnace

Wrong: open wall cavity connected to this return air plenum is allowing cellulose attic insulation to be pulled into the furnace

Image

Wrong – The batt insulation on this knee wall is not properly supported and there is no air sealed rigid backing to provide a solid air barrier.

Wrong – The batt insulation on this knee wall is not properly supported and there is no air sealed rigid backing to provide a solid air barrier.

Image

The attic knee walls were constructed from 2x6s and insulated with R-19 batt, backed with 1 inch of XPS foam board with taped joints to provide a solid air barrier over the insulated surfaces.

The attic knee walls were constructed from 2x6s and insulated with R-19 batt, backed with 1 inch of XPS foam board with taped joints to provide a solid air barrier over the insulated surfaces.

Image

Right - These raised heel roof trusses provide 16 inches of space over the outer walls for full insulation coverage at the attic perimeter.

Right - These raised heel roof trusses provide 16 inches of space over the outer walls for full insulation coverage at the attic perimeter.

Image

Right - These attic knee walls are insulated with rigid foam and sealed with spray foam to form a continuous air barrier at the gable end of this cathedral ceiling.

Right - These attic knee walls are insulated with rigid foam and sealed with spray foam to form a continuous air barrier at the gable end of this cathedral ceiling.

Image

The unvented attic is insulated along the underside of the roof deck with 7 inches (R-49) of closed-cell spray foam, providing vaulted ceilings and a conditioned knee wall space for ducting.

The unvented attic is insulated along the underside of the roof deck with 7 inches (R-49) of closed-cell spray foam, providing vaulted ceilings and a conditioned knee wall space for ducting.

Image

ICF walls and an attic sealed and insulated to R-63 on the underside of the roof deck with 10 inches of open‐cell spray foam plus 2.7 inches of closed‐cell spray foam provide a complete thermal break around this home.

ICF walls and an attic sealed and insulated to R-63 on the underside of the roof deck with 10 inches of open‐cell spray foam plus 2.7 inches of closed‐cell spray foam provide a complete thermal break around this home.

Image

Conceptual insulation at cape-style roof - roof cavity insulation with rigid insulation closure

Conceptual insulation at cape-style roof - roof cavity insulation with rigid insulation closure

CAD File

Attic Knee Walls

Guide

Guide describing how to insulate and air-seal attic knee walls and floor joist cavities under knee walls.

Attic Knee Walls

Video

Video describing how to insulate and air seal attic knee walls.

Attic Eave Minimum Insulation

Guide

Guide providing guidance on insulating attic eaves in new and existing single-family homes and multifamily buildings.

Walls Adjoining Porch Roof

Guide

This guide describes how to install a rigid air barrier to separate the porch attic from the conditioned space.

Installation of Cavity Insulation, Info-501

Reference

Article explaining installing cavity insulation.