All Other Ceilings

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Climate

ENERGY STAR Version 3, (Rev. 07)

Thermal Enclosure Checklist, Fully-Aligned Air Barriers. A complete air barrier shall be provided that is fully aligned with the insulation at interior or exterior surface of ceilings in Climate Zones 1-3; at interior surface of ceilings in Climate Zone 4-8. 

DOE Challenge Home

Exhibit 2: DOE Challenge Home Target Home. Infiltration (ACH50): Zones 1-2: 3; Zones 3-4: 2.5; Zones 5-7: 2; Zone 8: 1.5. Envelope leakage shall be determined by an approved verifier using a RESNET-approved testing protocol.

climate zone map

International Energy Conservation Code (IECC) Climate Regions

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Description

In simplest terms, a house is a six-sided assembly composed of four walls, a roof, and a floor. When these components are all connected, they comprise the building enclosure or the physical shell of the home. Within these assemblies are components that comprise the home’s thermal envelope (insulation) and air barrier. For the best performance, the home’s thermal layer should be fully aligned with (in full continuous contact with) the air barrier. According to the ENERGY STAR Thermal Enclosure System Rater Checklist (Version 3, Rev. 6), the air barrier may be required on the interior side of the insulation, the exterior side of the insulation, or both, depending on the building component and the climate. The ceiling air barrier can be on either the interior or exterior side of the insulation for homes in IECC Climate Zones 1-3, but in Climate Zones 4-8, it must be aligned with the interior surface of the ceiling (i.e., mudded, taped drywall).

 The ceiling air barrier should be continuous and all holes through it, for wiring, electrical boxes, light fixtures, flue and chimney pipes, duct chases, heating registers, soffits, etc., should be thoroughly air sealed before insulation is installed. See other air sealing for guides for instructions about specific air sealing situations. Wind dams and baffles should also be installed in the attic along the eaves in every rafter bay that has a soffit vent.  The wind dams provide a backing for the insulation so it doesn’t spill over the top plate and fall out of the soffit vents. Baffles are installed along the roof line to guide air from the soffit vents up along the underside of the roof, instead of having the air blow through the insulation, pushing it away from the eaves.

It is important to maintain a minimum amount of insulation, preferably equivalent to the insulation depth of the rest of the attic, over the top plates of the exterior walls. This will prevent cold spots along the interior walls and ensure the R-value across the ceiling. Building the roof with raised heel “energy” trusses will help allow the full height of insulation to be installed over the top plates. See Attic Eave Minimum Insulation for more information.

After all holes through the ceiling are air sealed and the baffles have been installed, the insulation can be installed in full contact with the ceiling drywall, which is the air barrier

Figure 1 - After all holes through the ceiling are air sealed and the baffles have been installed, the insulation can be installed in full contact with the ceiling drywall, which is the air barrier.

Baffles can be made of plastic, metal, cardboard, or molded rigid foam. The baffles provide an air space over the insulation to guide ventilation air from the soffit vents up along the underside of the roof deck

Figure 2 - Baffles can be made of plastic, metal, cardboard, or molded rigid foam. The baffles provide an air space over the insulation to guide ventilation air from the soffit vents up along the underside of the roof deck.

 

How to Air Seal and Insulate the Ceiling

 

1. Design the home with raised heel energy trusses ( if you are using trusses) or roof rafters with a raised top plate (if you are building the rafters on site).

 

 

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

Figure 3 - Raised heel, energy trusses extend further past the wall and are deeper at the wall allowing room for full insulation coverage over the top plate of the exterior walls.

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

Figure 4 - A site-built rafter roof with a raised top plate allows for more insulation underneath.

2. Thoroughly air seal all holes through the ceiling.

 

3. Install baffles in each rafter bay that has a vent. Choose and install the baffles correctly to provide the code-required minimum air space between the baffle and the roof deck.

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

Figure 5 - The soffit dam and baffle allow air to flow through the vents without disturbing the insulation covering the top plates.

4. Cover the ceiling deck with blown, batt, or spray foam insulation to the full height required to meet or exceed the minimum value for the climate zone. ENERGY STAR requires that all insulated ceiling surfaces meet the requirements for ceilings, regardless of slope (e.g., cathedral ceilings, tray ceilings, conditioned attic roof decks, flat ceilings, sloped ceilings).

Ensuring Success

Verify with a visual inspection that a continuous air barrier exists at the interior surface of ceilings in Climate Zones 4-8 and at the interior or exterior surface of ceilings in Climate Zones 1-3. This air barrier should be fully aligned with the insulation across the entire surface of the ceiling including at the eaves. Verify that wind dams and baffles are installed in every bay with a soffit vent to prevent wind washing. Measure baffles to confirm that the baffles meet the minimum code-required clearance between the baffle and the roof deck. 

Scope

All other ceilings

Fully Aligned Air Barriers

  1. At interior or exterior surface of ceilings in Climate Zones 1-3; at interior surface of ceilings in Climate Zones 4-8. Also, include barrier at interior edge of attic eave in all climate zones using a wind baffle that extends to the full height of the insulation. Include a baffle in every bay or a tabbed baffle in each bay with a soffit vent that will also prevent wind washing of insulation in adjacent bays.
  2. Install wind baffles with the minimum code required clearance between baffle and roof deck.

ENERGY STAR Notes:

An air barrier is defined as any durable solid material that blocks air flow between conditioned space and unconditioned space, including necessary sealing to block excessive air flow at edges and seams and adequate support to resist positive and negative pressures without displacement or damage. ENERGY STAR recommends, but does not require, rigid air barriers. Open-cell or closed-cell foam shall have a finished thickness >= 5.5 inches or 1.5 inches, respectively, to qualify as an air barrier unless the manufacturer indicates otherwise. If flexible air barriers such as house wrap are used, they shall be fully sealed at all seams and edges and supported using fasteners with caps or heads >= 1 inch in diameter unless otherwise indicated by the manufacturer. Flexible air barriers shall not be made of kraft paper, paper-based products, or other materials that are easily torn. If polyethylene is used, its thickness shall be >= 6 mil.

All insulated vertical surfaces are considered walls (e.g., exterior walls, knee walls) and must meet the air barrier requirements for walls. All insulated ceiling surfaces, regardless of slope (e.g., cathedral ceilings, tray ceilings, conditioned attic roof decks, flat ceilings, sloped ceilings), must meet the requirements for ceilings.

Training

Right and Wrong Images

Presentations

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Videos

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Compliance

ENERGY STAR Version 3, (Rev. 07)

Thermal Enclosure Checklist, Fully-Aligned Air Barriers. An air barrier is defined as any durable solid material that blocks air flow between conditioned space and unconditioned space, including necessary sealing to block excessive air flow at edges and seams and adequate support to resist positive and negative pressures without displacement or damage. ENERGY STAR recommends, but does not require, rigid air barriers. Open-cell or closed-cell foam shall have a finished thickness >= 5.5 inches or 1.5 inches, respectively, to qualify as an air barrier unless the manufacturer indicates otherwise. If flexible air barriers such as house wrap are used, they shall be fully sealed at all seams and edges and supported using fasteners with caps or heads >= 1 inch in diameter unless otherwise indicated by the manufacturer. Flexible air barriers shall not be made of kraft paper, paper-based products, or other materials that are easily torn. If polyethylene is used, its thickness shall be >= 6 mil. All insulated vertical surfaces are considered walls (e.g., exterior walls, knee walls) and must meet the air barrier requirements for walls. All insulated ceiling surfaces, regardless of slope (e.g., cathedral ceilings, tray ceilings, conditioned attic roof decks, flat ceilings, sloped ceilings), must meet the requirements for ceilings.      

DOE Challenge Home

Exhibit 1: Mandatory Requirements. Certified under ENERGY STAR Qualified Homes Version 3. Exhibit 2: DOE Challenge Home Target Home. Insulation levels shall meet or exceed the 2012 IECC (Table R402.1.1) and achieve Grade 1 installation, per RESNET standards. Infiltration (ACH50): Zones 1-2: 3; Zones 3-4: 2.5; Zones 5-7: 2; Zone 8: 1.5. Envelope leakage shall be determined by an approved verifier using a RESNET-approved testing protocol. Steel-frame ceilings, walls, and floors shall meet the insulation requirements of the 2012 IECC – Table 402.2.6. For ceilings with attic spaces, R-30 shall satisfy the requirement for R-38 and R-38 shall satisfy the requirement for R-49 wherever the full height of uncompressed insulation at the lower R-value extends over the wall top plate at the eaves. This exemption shall not apply if the alternative equivalent U-factor or total UA calculations are used.

2009 IECC

Ceiling/attic: Air barrier in any dropped ceiling/soffit is substantially aligned with insulation and any gaps are sealed.* Table 402.4.2 Air Barrier and Insulation Inspection Component Criteria, Air barrier and thermal barrier: Air permeable insulation is not used as a sealing material.

2009 IRC

Table N1102.4.2 Air Barrier and Insulation Inspection, Air barrier and thermal barrier: Air permeable insulation is not used as a sealing material.*

2012 IECC

Table R402.4.1.1 Air Barrier and Insulation Installation, Air barrier and thermal barrier: A continuous air barrier is installed in the building envelope including rim joists and exposed edges of insulation. Breaks or joints in the air barrier are sealed. Air permeable insulation is not used as a sealing material.*

2012 IRC

Table N1102.4.1.1 Air Barrier and Insulation Installation, Air barrier and thermal barrier: A continuous air barrier is installed in the building envelope including rim joists and exposed edges of insulation. Breaks or joints in the air barrier are sealed. Air permeable insulation is not used as a sealing material.*

*Due to copyright restrictions, exact code text is not provided. For specific code text, refer to the applicable code.

More Info.

Case Studies

None Available

References and Resources*

  1. Author(s): Lstiburek
    Organization(s): BSC
    Publication Date: May 2009

    Brochure about creating an air barrier by sealing drywall assemblies.

  2. Author(s): Lstiburek
    Organization(s): BSC
    Publication Date: February 2010

    Document providing background and approach for the prep work necessary prior to adding attic insulation - focusing on combustion safety, ventilation for indoor air quality, and attic ventilation for durability.

  3. Author(s): Southface Energy Institute, ORNL
    Organization(s): Southface Energy Institute, ORNL
    Publication Date: February 2000

    Information sheet with information about insulating and ventilating attics.

  4. Author(s): DOE
    Organization(s): DOE
    Publication Date: June 2013

    Standard requirements for DOE's Challenge Home national program certification.

  5. Author(s): EPA
    Organization(s): EPA
    Publication Date: June 2013

    Standard document containing the rater checklists and national program requirements for ENERGY STAR Certified Homes, Version 3 (Rev. 7).

  6. Author(s): Georgia Department of Community Affairs
    Organization(s): Georgia Department of Community Affairs
    Publication Date: January 2011

    Georgia state's minimum standard energy code, including state supplements and amendments.

  7. Author(s): Lstiburek
    Organization(s): BSC
    Publication Date: May 2009

    Information sheet about air sealing.

  8. Author(s): EPA
    Organization(s): EPA
    Publication Date: October 2011

    Guide describing details that serve as a visual reference for each of the line items in the Thermal Enclosure System Rater Checklist.

Last Updated: 08/15/2013

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