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Right – Seams in the deck sheathing are sealed with tape

Above Deck Rigid Foam Insulation for Existing Roofs

Guide describing the installation of insulating sheathing above the roof deck on existing homes. This retrofit assembly is appropriate for homes with conditioned attics or where the retrofit is intended to create a conditioned attic.

2x4 Raised Truss - Insulation Below Roof Deck CAD

DWG

PDF

Below Deck Spray Foam Insulation for Existing Roofs

Guide describing how to add spray foam insulation to the underside of the existing roof deck as part of the conversion of a vented attic to an unvented, insulated attic.

Right – A roller helps the tape to adhere over seams in the deck sheathing

2x10 Rafter - Insulation Above Roof Deck and In Rafter Cavity CAD

DWG

PDF

2x10 Rafter - Insulation Below Roof Deck In Rafter Cavity CAD

DWG

PDF

2x12 Rafter - Insulation Above Roof Deck and In Rafter Cavity CAD

DWG

PDF

2x12 Rafter - Insulation Below Roof Deck In Rafter Cavity CAD

DWG

PDF

Roof decking has adhered radiant barrier that is perforated, in addition to the nail holes

Three locations and methods for installing a roof deck radiant barrier in new construction

Publication Date

Mon, 06/01/2009 - 12:00

The attic is insulated along the underside of the roof deck with 8 inches of open-cell spray foam.

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

Spray foam insulates and air-seals the ceiling deck and top plates of this vented attic.

Publication Date

Fri, 02/01/2013 - 12:00

Right – Wind baffle installation maintains necessary code clearance between baffle and roof deck

Publication Date

Fri, 10/28/2011 - 12:00

Right - Closed-cell spray foam covers the ceiling and joists to insulate and air-seal the ceiling deck.

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

Publication Date

Fri, 10/15/2021 - 12:00

Right – Spray foam insulation is sprayed on the underside of the roof deck to provide a conditioned space in this low attic for the HVAC ducts.

Publication Date

Fri, 12/31/2021 - 12:00

In the attic, all of the top plate seams are sealed with canned spray foam before covering the ceiling deck with blown fiberglass.

Wrong – Roof underlayment is not fully adhered and roof deck seams are not sealed so roof is susceptible to high-wind events

Right – Roof underlayment is fully adhered and roof deck seams are sealed so roof is resistant to high-wind events

Right - The underside of the attic roof deck is insulated with open-cell spray foam to provide an insulated space for HVAC equipment.

Publication Date

Fri, 01/01/2010 - 12:00

There are three potential locations for an attic radiant barrier – adhered to the underside of the roof decking, hanging from the rafters, or on the ceiling insulation

Publication Date

Wed, 06/01/2005 - 12:00

Low-slope roof assemblies constructed of two deck sheathing layers sandwiching rigid foam, and topped with mechanically fastened membrane

IECC Climate Zone 2A: Unvented Attic with Spray Foam at Roof Deck, 2x6 Wall/CMU Wall, Elevated Slab

Publication Date

Wed, 10/18/2023 - 12:00

IECC Climate Zone 2A: Unvented Attic with Spray Foam at Roof Deck, 2x6 Wall/CMU Wall, Elevated Slab

Publication Date

Wed, 10/18/2023 - 12:00

Detail of an unvented cathedralized attic showing air-impermeable spray foam insulation plus batt insulation installed on the underside of the roof deck.

Baffles provide an air space over the insulation to guide ventilation air from the soffit vents up along the underside of the roof deck

Publication Date

Thu, 06/28/2012 - 12:00

Sloped roof with cavity spray foam insulation sprayed on underside of roof deck and covered with sprayed-on thermal or ignition barrier coating.

Publication Date

Fri, 05/01/2015 - 12:00

Right – Closed-cell polyurethane foam is sprayed on the underside of the roof deck to provide structural connections and seal seams in the sheathing to increase wind resistance

Spray foam insulation is applied along the underside of the roof deck to provide a conditioned and non-vented attic space for ducts and air handlers.

Reference

40% Whole-House Energy Savings in the Hot-Humid Climate, Volume 15

Author(s)

Baechler Michael C,

Gilbride Theresa L,

Hefty Marye G,

Cole Pam C,

Adams Karen T,

Noonan Chrissy F,

Love Pat M

Organization(s)

Pacific Northwest National Laboratory,

PNNL,

Oak Ridge National Laboratory,

ORNL,

U.S. Department of Energy,

DOE

A guidebook helping builders in hot-humid climates design and construct homes for energy efficiency, durability, health, safety, and comfort.

Publication Date

Thu, 09/01/2011 - 12:00

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.

To reduce the risk of condensation on the interior of the roof sheathing in cold weather, the ratio of exterior (above-deck) insulation must be increased as a percent of total attic insulation as outside temperature decreases

Publication Date

Sat, 10/01/2011 - 12:00

Right - This new sealed attic has 5.5 inches (R-20) of spray foam insulation along the underside of the roof deck providing a conditioned attic space for the heating and cooling ducts.

This attic was insulated with 5 inches of closed-cell spray foam on the underside of the roof deck plus 6.5 inches of blown fiberglass covered with sheetrock as a firebreak for a total R-58 roof assembly insulation value.

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.

Publication Date

Thu, 09/30/2021 - 12:00

The OSB roof decking product comes with an adhered radiant foil barrier which helps to prevent heat transfer in or out of the vented attic, while R-13 unfaced fiberglass fills the advanced-framed 2x6 walls.

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.

Unvented Insulated Sloped Roofs

Guide describing construction of sloped roofs that are unvented and are insulated above the roof deck.

Unvented Attic Insulation

Guide describing methods for insulating an unvented attic along the roof line.

Attic Air Sealing, Insulating, and Ventilating for Ice Dam Prevention

Information guide describing proper attic air-sealing, insulation, and ventilation to combat ice dam formation on roofs in cold climate zones.

Attic Radiant Barriers

Guide describing application of a radiant barrier layer in the attic to block radiant heat transfer between hot surfaces and heat-absorbing surfaces.

Condensation Control in Attics and Roofs in Cold Weather

Guide describing causes of condensation in attics and roof assemblies during cold weather and ways to reduce this condensation.

Vented versus Unvented Attic

Guide describing options for designing and locating the thermal boundary at either the attic floor or along the roof line in new and existing homes.

Air Sealing, Insulating, and Venting Attics and Roofs to Reduce Heat Gain

Information guide providing links to guides describing specific ways to air-seal, insulate, and ventilate attics and roofs to minimize heat gain in new and existing homes.

Cost Analysis of Roof-Only Air Sealing and Insulation Strategies on 1 1/2-Story Homes in Cold Climates

Author(s)

Ojczyk Cindy

Organization(s)

University of Minnesota,

U.S. Department of Energy,

DOE,

NothernSTAR

Publication Date

December, 2014

Report exploring alternative methods to find long-term solutions to energy loss in 1 ½-story homes to save energy, improve comfort, prevent frost buildup on the underside of the roof deck, and reduce the risk of ice dam formation/reformation.

Roof/Attic to Exterior Wall Air Control Upgrade

Guide outlining how to retrofit an exterior wall and/or attic to provide continuous air sealing.

Water Managed Roof – Re-roofing and Adding Insulation Over a Sloped Roof

Guide describing how to re-roof an existing home with a sloped and add insulation above the roof deck.

Air Sealing and Insulating Ceilings in Vented Attics

Guide describing how to air-seal and insulate a ceiling where the insulation is installed on top of the ceiling (on the attic floor) in a vented attic.

Air Sealing Drywall to Top Plate

Guide describing ways to seal drywall to the top plate of an exterior wall to air-seal the wall cavity.

Wind Washing

Guide describing wind washing and how to prevent it.

Controlling Moisture in Unvented Attics - Code Compliance Brief

Publication Date

May, 2017

The intent of this brief is to provide code-related information about controlling moisture in unvented attics by installing a vapor diffusion port/vent that would convey water vapor from an unvented attic to the outside when air-permeable insulation materials are installed and can be verified as being in compliance with the related codes and standards for residential construction. Providing consistent information to document compliance with codes and standards to all relevant parties responsible for verifying compliance (e.g., code officials, builders, contractors, designers, etc.) is expected to result in increased compliance and more timely, less challenging and more uniform plan review and field inspections.

Blown Insulation for Existing Vented Attic

Guide describing how to insulate a vented attic in an existing home using blown insulation added to the attic floor.

Support at Intervals for Flex Ducts

Guide describing how to hang ducts with supporting straps or saddles to adequately support ducts so they do not sag and are not pinched or compressed in a manner that would cause damage to the ducts, the duct insulation, or the duct air barrier covering.

Sealing and Insulating Existing Vented Attics - Code Compliance Brief

Publication Date

May, 2016

The intent of this brief is to provide code-related information about sealing and insulating existing vented attics to help ensure that the measure will be accepted as being in compliance with the code. Providing the same information to all interested parties (e.g., code officials, builders, contractors, designers, etc.) is expected to result in increased compliance and fewer innovations being questioned at the time of plan review and/or field inspection.