BASC Search | Building America Solution Center

Unvented Attic Insulation

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

Measure the depth of insulation

Publication Date

Fri, 01/01/2010 - 12:00

Insulation Below Attic Platforms

Guide describing how to install insulation below attic platforms

Attic Eave Minimum Insulation

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

Batt Insulation for Existing Vented Attics

Guide describing how to increase insulation in existing homes by installing batt insulation on the ceiling plane of a vented attic.

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.

Wrong – Insulation will not be aligned with air barrier

Publication Date

Fri, 10/28/2011 - 12:00

Failure in attic insulation effectiveness caused by wind washing pushing insulation away from the edges of the attic space.

Publication Date

Tue, 12/01/2009 - 12:00

The attic kneewall and the open floor cavities under kneewall are both sealed and insulated in one step with spray foam insulation

Publication Date

Tue, 12/01/2009 - 12:00

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.

Wrong – The framing will not allow for required insulation depth.

Publication Date

Fri, 10/28/2011 - 12:00

Right – The framing allows for required insulation depth.

Publication Date

Fri, 10/28/2011 - 12:00

Spray Foam Insulation Applied to Existing Attic Floor

Guide describing how to apply spray foam insulation to ceilings in existing homes.

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 – The knee wall is properly insulated and air sealed.

Publication Date

Fri, 10/28/2011 - 12:00

1 inch exterior insulation sheathing as attic eave baffle and vent

DWG

PDF

Right – HVAC platform installed to allow for proper insulation depth

Publication Date

Fri, 10/28/2011 - 12:00

Right – Insulation installed to correct depth and will be aligned with air barrier

Publication Date

Fri, 10/28/2011 - 12:00

Install insulation under platforms constructed in the attic for storage or equipment.

Publication Date

Fri, 10/28/2011 - 12:00

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

Publication Date

Fri, 10/28/2011 - 12:00

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

Publication Date

Fri, 10/28/2011 - 12:00

Air seal and insulate drawer and closet boxes in attic kneewalls

Reference

Retrofit Techniques and Technologies: Air Sealing, Volume 10

Author(s)

Baechler Michael C,

Gilbride Theresa L,

Hefty Marye G,

Cole Pam C,

Williamson Jennifer,

Love Pat M

Organization(s)

Pacific Northwest National Laboratory,

PNNL,

Oak Ridge National Laboratory,

ORNL,

U.S. Department of Energy,

DOE

Report identifying the steps to take, with the help of a qualified home performance contractor, to seal unwanted air leaks while ensuring healthy levels of ventilation and avoiding sources of indoor air pollution.

Publication Date

Mon, 04/12/2010 - 12:00

2009-2021 IECC and IRC Minimum Insulation Requirements for New Homes

Table adapted from Table R402.1.1 in the 2009 and 2012 IECC and Table R402.1.2 in the 2015 and 2018 IECC (Table N1102.1 in 2009 IRC, Table 1102.1.1 in 2012 IRC, and Table N1102.1.2 in 2015 and 2018 IRC).

Wrong – The framing and wind baffle installation will not allow for required insulation depth.

Publication Date

Fri, 10/28/2011 - 12:00

Wrong – Drop down stairs do not have insulation cover installed

Publication Date

Fri, 10/28/2011 - 12:00

Wrong – Attic access panel does not have an insulation cover installed

Publication Date

Fri, 10/28/2011 - 12:00

A standard site-built roof of rafters may pinch the insulation at the eaves

Publication Date

Sat, 01/01/2011 - 12:00

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

Publication Date

Fri, 10/28/2011 - 12:00

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

Publication Date

Fri, 10/28/2011 - 12:00

Right – Top and bottom plates were installed prior to backing and insulation.

Publication Date

Fri, 10/28/2011 - 12:00

Wrong - Wind baffle installation will not allow insulation over the top plate.

Publication Date

Fri, 10/28/2011 - 12:00

Wrong – No blocking installed to prevent attic insulation from falling into stairs and opening

Publication Date

Fri, 10/28/2011 - 12:00

A site-built rafter roof with a raised top plate allows for more insulation underneath.

Publication Date

Sat, 01/01/2011 - 12:00

Sloped roof with cavity spray foam insulation, strapping, and gypsum board thermal barrier

Publication Date

Fri, 05/01/2015 - 12:00

Limited attic access can make inspections for missing air barriers and insulation challenging

Publication Date

Wed, 04/01/2015 - 12:00

Install a continuous air barrier below or above ceiling insulation and install wind baffles.

Publication Date

Sat, 10/01/2011 - 12:00

Right - Wind baffle installation will allow proper insulation depth over the top plate.

Publication Date

Fri, 10/28/2011 - 12:00

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

Publication Date

Fri, 10/28/2011 - 12:00

Right – Blocking has been installed around the perimeter of this attic access to prevent insulation falling into the house

Publication Date

Fri, 10/28/2011 - 12:00

Flat roof with cavity spray foam plus loose-fill insulation and gypsum board thermal barrier.

Publication Date

Fri, 05/01/2015 - 12:00

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

The soffit dam and baffle allow air to flow through the vents without disturbing the insulation covering the top plates

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

Publication Date

Sat, 01/01/2011 - 12:00

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

Publication Date

Tue, 12/01/2009 - 12:00

After all holes through the ceiling are air-sealed and the baffles have been installed, then the insulation can be installed.

Publication Date

Thu, 06/28/2012 - 12:00

Right – Attic access hatch has been properly insulated by attaching a fiberglass batt, gasketed, and opening has blocking

Publication Date

Sat, 10/01/2011 - 12:00

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.

Publication Date

Fri, 10/28/2011 - 12:00

Right-- IR photo shows how effectively spray foam insulated/air sealed attic kneewall and the floor cavities under kneewall

Publication Date

Tue, 12/01/2009 - 12:00

Limited attic access may make it necessary to use a bore scope when inspecting for missing air barriers and insulation in existing buildings.

Publication Date

Tue, 12/01/2009 - 12:00

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

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.

Publication Date

Sat, 01/01/2011 - 12:00

Attic Knee Walls

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

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.

Wind Washing

Guide describing wind washing and how to prevent it.

Dropped Ceiling/Soffit Below Unconditioned Attic

Guide describing how to insulate and air-seal dropped ceilings and soffits to prevent air leakage.

Air Sealing Attic Access Panels/Doors/Stairs

Guide describing how to air-seal attic access panels, doors, and stairs to provide a continuous air barrier at the ceiling.

Ducts in Raised Ceiling Sections

Guide describing method for designing and installing ducts in a raised ceiling chase.

Install Top Plates or Blocking at the Top of Walls Adjoining Unconditioned Spaces

Guide describing how to correctly air-seal a wall with missing top plates or open wall cavities.

DOE ZERH HIA 2017 Case Study: United Way of Long Island, United Veterans Beacon House, Huntington Station, NY

Author(s)

Pacific Northwest National Laboratory,

U.S. Department of Energy

Organization(s)

PNNL,

DOE

Publication Date

September, 2017

Case study showing project and performance data and energy-efficiency measures for a DOE 2017 Housing Innovation Award winning home that was certified to the DOE Zero Energy Ready Home criteria.

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.

Air Sealing Duct and Flue Shafts

Guide describing how to air-seal duct and flue shafts.

Air-seal the attic kneewall door opening with weatherstripping.

Publication Date

Thu, 01/01/2009 - 12:00

Technology Solutions Case Study: Complete and Fully Aligned Air Barrier

Author(s)

Pacific Northwest National Laboratory

Organization(s)

PNNL

Publication Date

August, 2012

Case study describing the elimination of excessive humidity in the attic of a multi-floor, single-family home that was causing condensation and water damage along the roof and eaves.

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.

DOE ZERH HIA 2017 Case Study: Thrive Home Builders, Courtyard Rows, Lone Tree, CO

Author(s)

Pacific Northwest National Laboratory,

U.S. Department of Energy

Organization(s)

PNNL,

DOE

Publication Date

September, 2017

Case study describing a DOE Zero Energy Ready Home 2017 Housing Innovation Award winner that scored HERS 41 without PV and 8 with PV.

Air Sealing Bathroom and Kitchen Exhaust Fans

Guide describing how to air-seal bathroom and kitchen exhaust fans.

Form a sheet metal shield around the flue pipe

Pre-Retrofit Assessment of Attics, Ceilings, and Roofs

Information guide describing things to consider in the attic, ceiling, or roof before attempting retrofits of items including HVAC, wiring, or structural systems.

Form sheet metal shield around pipe keeping 3-inch clearance

Install wood framing cross pieces in the attic rafter bays on each side of the duct chase

The thermal boundary for a gable roof can be located at either a) the flat ceiling with a vented attic or b) the roof line for an unvented attic

DOE ZERH HIA 2013 Case Study: Preferred Builders, Old Greenwich, Connecticut

Author(s)

Pacific Northwest National Laboratory,

U.S. Department of Energy

Organization(s)

PNNL,

DOE

Publication Date

April, 2013

Case study describing a DOE Zero Energy Ready Home 2013 Housing Innovation Award Winner in Old Greenwich CT, that scored HERS 42 without PV and HERS 20 with PV.

A low-sloped shed roof with the thermal boundary located at either a) the flat ceiling with a vented attic or b) the roof line for an unvented attic

A 1- and ½-story home with a room located in the attic and the thermal boundary located at either a) the walls and ceiling of the attic room with small vented attic spaces or b) the roof line for an unvented attic

This kneewall has no top plate and the resulting gap provides a wide-open pathway for air and vapor to travel between the living space and the attic

Wrong – No top plate was installed.

Publication Date

Fri, 10/28/2011 - 12:00

Wrong – There is no weather stripping or gasket around the attic stair hatch

Publication Date

Fri, 10/28/2011 - 12:00

Wrong – No rigid backing was installed on the attic knee wall.

Publication Date

Fri, 10/28/2011 - 12:00

Air seal attic access panels and drop-down stairs to minimize air leakage.

Publication Date

Fri, 10/28/2011 - 12:00

Right - Continuous wall sheathing and blocking has been installed to brace the raised heel trusses.

Publication Date

Sat, 10/01/2011 - 12:00

Right – Attic access door has foam and rubber weatherstripping installed that remains in contact when closed.

Publication Date

Fri, 10/28/2011 - 12:00

Investigating Solutions to Wind Washing Issues in 2-Story Florida Homes; Phase 1

Author(s)

Cummings James B,

Withers Charles R,

LaHiff Ian L

Organization(s)

Florida Solar Energy Center,

FSEC

Publication Date

December, 2009

Research study describing field testing performed in 32 two-story Florida homes to characterize wind washing failures of the house air and thermal boundary.

Opportunities for Energy Conservation and Improved Comfort From Wind Washing Retrofits in Two-Story Homes - Part I

Author(s)

Withers Charles R,

Cummings James B

Organization(s)

Florida Solar Energy Center,

FSEC

Publication Date

September, 2010

Report highlighting the evaluation methods used and extent of wind washing found in a study analyzing wind washing in thirty-two two-story homes.

Air seal the attic access panel with weather stripping

Reference

Retrofit Techniques and Technologies: Air Sealing, Volume 10

Author(s)

Baechler Michael C,

Gilbride Theresa L,

Hefty Marye G,

Cole Pam C,

Williamson Jennifer,

Love Pat M

Organization(s)

Pacific Northwest National Laboratory,

PNNL,

Oak Ridge National Laboratory,

ORNL,

U.S. Department of Energy,

DOE

Report identifying the steps to take, with the help of a qualified home performance contractor, to seal unwanted air leaks while ensuring healthy levels of ventilation and avoiding sources of indoor air pollution.

Publication Date

Mon, 04/12/2010 - 12:00

Air seal the attic access pull-down stairs opening with weather stripping

Reference

Retrofit Techniques and Technologies: Air Sealing, Volume 10

Author(s)

Baechler Michael C,

Gilbride Theresa L,

Hefty Marye G,

Cole Pam C,

Williamson Jennifer,

Love Pat M

Organization(s)

Pacific Northwest National Laboratory,

PNNL,

Oak Ridge National Laboratory,

ORNL,

U.S. Department of Energy,

DOE

Report identifying the steps to take, with the help of a qualified home performance contractor, to seal unwanted air leaks while ensuring healthy levels of ventilation and avoiding sources of indoor air pollution.

Publication Date

Mon, 04/12/2010 - 12:00

New Whole-House Solutions Case Study: Tom Walsh & Co., New Columbia, Portland, OR

Author(s)

Pacific Northwest National Laboratory

Organization(s)

PNNL

Publication Date

February, 2013

Case study describing a new construction building project of 20 homes that earned HERS scores that represent greater than 50% energy savings in heating and cooling over the 2004 IECC.

Calculating Attic Passive Ventilation

Information guide describing how to calculate attic passive ventilation with example calculations.

New Whole-House Solutions Case Study: Schneider Homes, Inc., Village at Miller Creek, Burien, WA

Author(s)

Pacific Northwest National Laboratory

Organization(s)

PNNL

Publication Date

February, 2013

Case study describing new home construction in the marine climate that achieved 50% savings over the 2004 IECC.

Whole House Ventilation Strategies for Existing Homes

Guide describing how to select and install whole-house ventilation systems for existing homes.