Insulation Installation (RESNET Grade 1)

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ENERGY STAR Version 3, (Rev. 07)

Thermal Enclosure Checklist, Quality-Installed Insulation. All ceiling, wall, floor, and slab insulation shall achieve RESNET-defined Grade I installation or, alternatively, Grade II for surfaces that contain a layer of continuous, air impermeable insulation >= R-3 in Climate Zones 1 to 4, >= R-5 in Climate Zones 5 to 8.

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International Energy Conservation Code (IECC) Climate Regions

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Description

To meet the requirements of ENERGY STAR Ver. 3, Rev. 7, all ceiling, wall, floor, and slab insulation must achieve RESNET-defined Grade I installation or, alternatively, Grade II for surfaces that contain a layer of continuous air-impermeable insulation that is greater than or equal to R-3 in Climate Zones 1 to 4, and greater than or equal to R-5 in Climate Zones 5 to 8.

Grade I installation requires that the insulation material uniformly fill each cavity side to side and top to bottom, without substantial gaps or voids around obstructions, and that it be split and/or fitted tightly around wiring and other services in the cavity.

Gaps, voids, and compressions that cause the insulation to lose contact with the surface it is intended to insulate can cause cold spots in walls, which may encourage the formation of condensation in the wall cavity.  

Blown insulation such as loose fiberglass, cellulose, or mineral wool fibers flow easily around obstructions, such as wiring and piping, to provide complete coverage in the cavities. To install blown insulation, the open cavities are first covered with a netting that is stapled to the stud faces. A slit is cut in the netting in each cavity and the insulation is installed with a hose inserted through the slit. The installer can easily see where the insulation is going to ensure that each cavity is completely filled without voids. 

Spray foam is another option that readily fills areas around obstructions in wall cavities, and it has the advantage of providing both air sealing and insulation. The foam completely fills the open wall cavities and is trimmed flush with the stud faces before installing dry wall. Spray foam insulation is made of petroleum, soy, or castor oil-based polyurethane and is available in open-cell, low-density products or closed-cell, high-density products. Both insulate and air seal; high-density products can also provide a vapor barrier. Another option is sprayed-on cellulose or mineral wool that is mixed with adhesive and water then sprayed into the open cavities and allowed to dry before drywalling. If batt insulation is used, it must be cut to fit around any wiring or piping installed in the wall cavities. 

Regarding insulation levels, to meet ENERGY STAR Ver. 3, Rev. 7, a home must meet or exceed the component insulation requirements in the 2009 IECC, Table 402.1.1. For more information on insulation levels and exceptions that might apply, see IECC Code Level Insulation.

In depth information about insulation, including descriptions of the many types of insulation available, their R-values, applications and advantages and disadvantages of each kind, and installation guidance can be found in the Building America Best Practices Series Volume 17: Insulation, A Guide for Contractors to Share with Homeowners.  

How to Install Insulation to RESNET-Defined Grade I 

1.  Install insulation without misalignments, compressions, gaps, or voids in all wall cavities along the thermal barrier of the house.  

Unfaced fiberglass batt insulation is installed to completely fill the wall cavities

Figure 1 - Unfaced fiberglass batt insulation is installed to completely fill the wall cavities and is sliced to fit around wiring, piping, and other obstructions in the wall cavities. Reference 

This faced fiberglass batt insulation was incorrectly installed 

Figure 2 - This faced fiberglass batt insulation was incorrectly installed; it should be cut to fit around wiring and obstructions so that it can completely fill the wall cavity without compressions and voids. Reference  

2.  Install wall insulation so that it is enclosed on all six sides in each wall cavity. It should be in substantial contact with the sheathing material on at least one side (interior or exterior) of the cavity.

Blown fiberglass insulation fills netted wall cavities

Figure 3 - Blown fiberglass insulation fills netted wall cavities and flows easily around wiring and other obstructions to provide a uniform insulating layer without gaps or voids. Reference 

Blown cellulose insulation completely fills the netted wall and ceiling cavities  

Figure 4 - Blown cellulose insulation completely fills the netted wall and ceiling cavities and flows easily around wiring and other obstructions to provide a uniform insulating layer without gaps or voids. Reference 

 Spray foam insulation is installed in open wall cavities to air seal and insulate

Figure 5 - Spray foam insulation is installed in open wall cavities to air seal and insulate. Reference 

3.  Faced batt insulation should be stapled to the surface of framing. Side-stapling is permitted, provided the tabs are stapled neatly (no buckling), the batt is only compressed at the edges of each cavity to the depth of the tab itself, and the batt meets the other requirements of Grade I.

Faced fiberglass batt insulation can be stapled to the stud faces or slightly inset

Figure 6 - Faced fiberglass batt insulation can be stapled to the stud faces or slightly inset, but avoid compressing the batts and slit the insulation to fit around wiring and other obstructions.  Reference

4.  Install slab edge insulation for slab-on-grade floors if the floor surface is less than 12 inches below grade and if required by code in your climate zone. Slab insulation should extend to the top of the slab to provide a complete thermal break. If the insulation is installed between the exterior wall and the edge of the interior slab, the insulation may be cut at a 45-degree angle away from the exterior wall, allowing the poured slab concrete to cover and protect the top edge of the insulation.

Insulating the slab edge will keep the floor warmer and reduce the potential for condensation and elevated relative humidity by allowing the inside surface temperature of the slab perimeter to more closely track the home’s interior temperature. If the slab is monolithic with a grade beam (Figure 8), the insulation is installed on the exterior of the slab edge/grade beam and continues vertically to the bottom of the grade beam. Use insulation material that is appropriate for ground contact such as XPS, rigid fiberglass, or rigid rock wool and use insect controls appropriate for the region. The above-ground portion of the rigid foam should be protected from UV and impact damage with coated fiber cement board.

Rigid foam slab edge insulation is installed along the exterior edge of a monolithic slab foundation

Figure 7 - Rigid foam slab edge insulation is installed along the exterior edge of a monolithic slab foundation. Reference 

When the slab is independent from the perimeter foundation wall, insulation may be installed either on the exterior of the foundation wall or between the foundation wall and the slab (Figure 9), which provides more protection from the elements. When the insulation is between the foundation wall and the slab, it forms a bond break and also extends horizontally under the slab either at the perimeter or under the entire slab.  

 

Rigid foam forms an insulating bond break between the foundation wall and the slab

Figure 8 - Rigid foam forms an insulating bond break between the foundation wall and the slab. Reference 

5.  Where an insulated wall separates a garage, patio, porch, or other unconditioned space from the conditioned space of the house, install slab insulation to provide a thermal break between the conditioned and unconditioned slab. Where specific details cannot meet this ENERGY STAR Ver. 3, Rev 6. requirement, provide the detail to EPA to request an exemption prior to the home’s qualification. 

Ensuring Success

Raters are required to inspect and probe in, around, or through the insulation and/or vapor retarder in several places to see whether these requirements are met. During inspection, insulation and vapor retarders may be cut or pulled away so raters can see installation details. The raters should replace or repair the vapor retarder and insulation as necessary. During inspection (typically before drywall is installed), if the exterior sheathing is visible from the building interior through gaps in the cavity insulation material, it is not considered a Grade I installation.

Scope

Batt insulation should be cut to fit around wiring so that insulation can completely fill the wall cavity

High Performance Insulation

 All ceiling, wall, floor, and slab insulation shall achieve RESNET-defined Grade I installation or, alternatively, Grade II for surfaces that contain a layer of continuous, air impermeable insulation >= R-3 in Climate Zones 1 to 4, >= R-5 in Climate Zones 5 to 8:

  1. Install insulation without misalignments, compressions, gaps, or voids in all wall cavities along the thermal barrier of the house.

ENERGY STAR Notes:

What is grade I installation? 

Grade I installation requires that the insulation material uniformly fill each cavity side-to-side and top-to-bottom, without substantial gaps, or voids around obstructions (such as blocking or bridging), and be split, installed, and/or fitted tightly around wiring and other services in the cavity.

To attain a rating of Grade I, wall insulation shall be enclosed on all six sides, and shall be in substantial contact with the sheathing material on at least one side (interior or exterior) of the cavity.

For faced batt insulation, Grade I can be designated for side-stapled tabs, provided the tabs are stapled neatly (no buckling), and provided the batt is only compressed at the edges of each cavity, to the depth of the tab itself, and provided the batt meets the other requirements of Grade I.

How do raters inspect insulation?

Raters are required to inspect and probe in, around, or through the insulation and/ or vapor retarder in several places to see whether these requirements are met.

During inspection, insulation and vapor retarders may be cut or pulled away so raters can see installation details. The raters should replace or repair the vapor retarder and insulation as necessary. During inspection (typically before drywall is installed), if the exterior sheathing is visible from the building interior through gaps in the cavity insulation material, it is not considered a Grade I installation.

Insulation levels in a home shall meet or exceed the component insulation requirements in the 2009 IECC - Table 402.1.1. The following exceptions apply:

  1. Steel-frame ceilings, walls, and floors shall meet the insulation requirements of the 2009 IECC – Table 402.2.5. In CZ 1 and 2, the continuous insulation requirements in this table shall be permitted to be reduced to R-3 for steel-frame wall assemblies with studs spaced at 24-inch on center. This exception shall not apply if the alternative calculations in d) are used;
  2. 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 calculations in d) are used;
  3. For ceilings without attic spaces, R-30 shall satisfy the requirement for any required value above R-30 if the design of the roof / ceiling assembly does not provide sufficient space for the required insulation value. This exemption shall be limited to 500 square feet or 20% of the total insulated ceiling area, whichever is less. This exemption shall not apply if the alternative calculations in d) are used;
  4. An alternative equivalent U-factor or total UA calculation may also be used to demonstrate compliance, as follows:

An assembly with a U-factor equal or less than specified in 2009 IECC Table 402.1.3 complies.

A total building thermal envelope UA that is less than or equal to the total UA resulting from the U-factors in Table 402.1.3 also complies. The insulation levels of all non-fenestration components (i.e., ceilings, walls, floors, and slabs) can be traded off using the UA approach under both the Prescriptive and the Performance Path. Note that fenestration products (i.e., windows, skylights, doors) shall not be included in this calculation. Also, note that while ceiling and slab insulation can be included in trade-off calculations, Items 4.1 through 4.3 of the Checklist shall be met regardless of the UA tradeoffs calculated. The UA calculation shall be done using a method consistent with the ASHRAE Handbook of Fundamentals and shall include the thermal bridging effects of framing materials. The calculation for a steel-frame envelope assembly shall use the ASHRAE zone method or a method providing equivalent results, and not a series-parallel path calculation method.

Consistent with the 2009 IECC, slab edge insulation is only required for slab-on-grade floors with a floor surface less than 12 inches below grade. Slab insulation shall extend to the top of the slab to provide a complete thermal break. If the top edge of the insulation is installed between the exterior wall and the edge of the interior slab, it shall be permitted to be cut at a 45-degree angle away from the exterior wall.

Where an insulated wall separates a garage, patio, porch, or other unconditioned space from the conditioned space of the house, slab insulation shall also be installed at this interface to provide a thermal break between the conditioned and unconditioned slab. Where specific details cannot meet this requirement, partners shall provide the detail to EPA to request an exemption prior to the home’s qualification. EPA will compile exempted details and work with industry to develop feasible details for use in future revisions to the program. See a list of currently exempted details.

Training

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Compliance

ENERGY STAR Version 3, (Rev. 07)

Thermal Enclosure Checklist, Quality-Installed Insulation. All ceiling, wall, floor, and slab insulation shall achieve RESNET-defined Grade I installation or, alternatively, Grade II for surfaces that contain a layer of continuous, air impermeable insulation >= R-3 in Climate Zones 1 to 4, >= R-5 in Climate Zones 5 to 8.

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 the 2012 IECC and achieve Grade 1 installation, per RESNET standards. 

2009 IECC

Section 303.2 Installation. All materials, systems, and equipment to be installed per the manufacturer’s instructions and the International Building Code.

2012 IECC

Section R303.2 Installation. All materials, systems, and equipment to be installed per the manufacturer’s instructions and the International Building Code or International Residential Code, as applicable.

More Info.

Case Studies

  1. Author(s): PNNL
    Organization(s): PNNL
    Publication Date: April 2012

    Case study about a new home builder that strives to address health, safety, and durability issues in a hot and humid climate.

  2. Author(s): PNNL
    Organization(s): PNNL
    Publication Date: January 2013

    Case study about a builder in Georgia that designs energy-efficient homes for a green community, yielding homes with HERS scores as lowas 59 and electric bills as low as $50 a month.

  3. Author(s): PNNL
    Organization(s): PNNL
    Publication Date: April 2012

    Case study about a new construction building project of 20 luxury homes in northern New Jersey that were more energy efficient than ENERGY STAR and met the 50% energy savings requirements of the federal tax credit for new homes.

References and Resources*

  1. Author(s): Baechler, Gilbride, Hefty, Cole, Williamson, Love
    Organization(s): PNNL, ORNL
    Publication Date: September 2010

    Report providing builders in marine climates with guidance for building homes that have whole-house energy savings of 40% over the Building America benchmark with no added overall costs for consumers.

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

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

  3. 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).

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

    Information sheet about insulating slabs.

  5. 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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