How to Achieve All Season Insulation and Air Barriers for Your Home

Your building's insulation and air tightness can follow guidelines of the independent rating of "Energy Performance" homes similar to the EPA "Thermal Bypass Inspection Checklist" which also covers "Energy Star" homes and fixture installations, etc. It calls for a sealed air-barrier and how it is done/certified. Here are some considerations of what that all requires to do -- and some exceptions. Because building an "Energy Star home" is a form of green building, most green builders and green home owners need to face and master oodles of red-tape to achieve the actual ratings.[1]

So, here are points on the checklist for Energy Star path or taking the Energy Performance path which is similar but less exacting in detail and precision.


  1. 1
    Examine three totally different ways that heat energy works with the laws of "heat-loss or heat-gain". Those are -- (i.) air passing through, or (ii.) thermal heat waves transmitting through solid materials, and even slowly through fluffy insulation and "dead air" -- and by (iii.) heat radiation and rays traveling in all 3 common states of matter. Infrared "as deep-penetrating heat rays" and ultraviolet (UV -- as in sun-light) can travel easily through a vacuum! Heat convection is heat rising -- and also, spreading out in all directions.

    Understand that it is really heat that has to be stopped -- not cold! Well, sure we block-off/block-out cold air and harsh unheated, winter winds blowing... Refrigerators/freezers are insulated to keep heat from being absorbed! Heat is a real commodity, but "cold" does not exist, as such: cold is only "less heat!" -- it's just heat moving and so losing of heat, heat lost (heat is lost from a building in cold weather; No! cold is not gained, at all!), the relative absence of heat! Air conditioners remove heat from the ambient, interior environment out to the external atmosphere.
    • The two main ways are found in section one of the six sections in the EPA's "Thermal Bypass Checklist":

      What Happens and How They Are Different:

      Air and Thermal barriers (The "Air Barrier" stops GAS (air blowing or seeping) versus "Thermal Barrier" including (i) HEAT WAVE traveling in soft, fluffy insulation that hinders/slows it [USE solid foam to stop heat conduction into the wooden or steel studs, joists and beams] -- and/or (ii) to REFLECT INFRARED radiant heat (rays) back [USE "mirror-like plastic backing" ON foam or ON plywood/oriented strand board (OSB)],

      Where that transpires:

      ~ 2.)
      Walls adjoining exterior or unconditioned spaces,

      ~ 3.) Floors between conditioned and exterior spaces,

      ~ 4.) Shafts (stairwells, skylights, etc.),

      ~ 5.) Attic and ceiling,

      ~ 6.) Common walls between dwelling units (town home, duplex, etc.).
  2. 2
    Insulate and create air barriers (durable seal) for floors, walls, ceilings (extensions, attachments, openings) on all six sides of your home/building (insulated box) -- top, bottom, back, front, left, and right.: external air tightness, wind tightness, encapsulation.[2]
    • Know the EPA's Checklist definition of an air barrier: “any solid material that blocks air flow between a conditioned space and an unconditioned space, including necessary sealing to block excessive air flow at edges and seams” — but “solid” can be interpreted in various ways; taken literally, the word refers to any substance that is not a liquid or a gas/vapor, but means a durable seal, so that sometimes is a house wrap like Tyvek, spun polyester (which is a highly breathable), but it does not pass liquid water -- or use asphalt/felt paper as a "solid" air barrier, also called a "water resistant barrier" (WRB).
  3. 3
    Understand conduction where heat flows through, and across more conductive materials in an otherwise well-insulated wall, floor or ceiling, for significant heat loss.
    • Use sprayed foam or foam board to interrupt heat flow into wood and metal components, where possible to minimize thermal exchange/flow by placing rigid foam board, for example between heated space and exterior siding sheathing -- or unheated attic space and ceiling.
    • An extreme problem is steel studs or beams in an insulated wall, ceiling or floor that would severely reduce the overall energy performance of that wall, because of thermal conduction, (exchange/flow) through the steel.
    • Yes, wood studs and joist do, also, conduct heat much more so than the insulation between the studs.
  4. 4
    Watch out for several areas where your builders might forget to include two or some of all three categories:
    • Exterior air barrier (on all 6 sides),
    • Interior air barriers (behind certain areas),
    • Insulation, including in openings, doors and windows and around them including "weather stripping, gaskets" at openings.
  5. 5
    Install internal barriers and insulation as mandatory measures for an "Energy Star Home", with the EPA Thermal Bypass Checklist (for example, drywall or foam "Thermo-ply" board) on the interior side of wall insulation behind a metal fireplace (and several similar areas) in colder climate zones.
  6. 6
    If builders are in warm climates (climate zones 1 through 3), they may eliminate the interior air barrier in several places that are required in zones 4 and higher (colder) -- but are still required in an "Energy Star Home" in all zones or as long as the insulation is fully supported in place and is installed according to RESNET’s insulation installation requirements for a "Grade One" performance rating,:
    • Over the insulation behind a metal fireplace (fire-rated drywall board),
    • Behind a tub/shower or tub (such as blueboard drywall or concrete board),
    • Behind attic knee walls (low walls -- seen with slanted attic ceilings),
    • At skylight shaft walls, and
    • At all staircase walls.
  7. 7
    Understand that the required interior insulation and barriers also include:
    • Behind tub/shower units "on exterior walls";
    • Behind zero-clearance metal fireplaces;
    • On walls at either side of attic stairs;
    • At interior soffits (for example, kitchen cabinet soffits);
    • At exterior walls;
    • Above porch ceilings.
  8. 8
    Insulate and weatherstrip around attic access doors and hatches.
  9. 9
    Fill the joist area in a bonus-room floor over a garage: The insulation should be in full contact with both the subfloor above and the exterior air barrier below, which is often a drywall ceiling in the garage.
    • Use cans of spray foam -- unless the builder/remodeler installs it with high volume spray foam equipment, and then the exterior air barrier is the exterior surface of the cured foam.
      • Canned foam is great for owners improving both air and thermal barriers and for small remodeling projects, for achieving a good/solid barrier.
  10. 10
    Insulate the edges of slabs in climate zones 4 or higher/colder — a requirement that can also be found in the International Residential Code.
  11. 11
    Realize there are exceptions to the "two-air-barrier" (internal and external) -- while this is about the rules:
    1. Ventilated airspace including the exterior air barrier can be omitted above insulation installed in an unfinished/non-living space of an attic floor, but adequate ventilation is usually desirable;
    2. The interior air barrier can be omitted at rim joists sometimes, but often should be sealed;
    3. The interior air barrier (behind insulation) can be omitted in warmer climate zones. (zones 1 through 3). The Thermal Bypass Checklist (such as installing all insulation according to RESNET’s "Grade One" insulation installation guidelines) is required both for builders following the path to obtaining an "Energy Star label" — using a “builder option package,” (BOP) — as well as for builders following the "Performance Home path" (can be somewhat sloppy -- but very sloppy insulation installs will warrant downgrading by the rater, resulting in a performance value "below that of a Grade One installation"). The Checklist has 25 items. While at least 19 of these items must be verified by a third-party home rater, up to 6 of the items can be “self-certified” by the builder.


  • In the official Thermal Bypass Checklist Guide, the EPA states, “Generally, the Thermal Bypass Inspection Checklist requires a sealed air-barrier on all six sides of insulation (top, bottom, back, front, left, and right); however, there are a few exceptions as noted throughout the Checklist.” The Checklist notes that “insulation shall be installed in full contact with [a] sealed interior and exterior air barrier.”
  • Energy Star also involves appliances, heat and air systems, water heating, lighting, home electronics, etc. besides home construction.
  • “Air barrier” -- The EPA uses of that term two ways and they need to be differentiated between

    (1) How it is usually understood as external (main barrier) against in-/ex-filtration, using barrier with seam-sealing/or adequate overlap (6 inches or so) of air barrier installations:

    Including vinyl/latex caulk, rubber gaskets, or that great canned spray foam.

    (2) "Versus", installing an internal layer to "seal"/enclose insulation that would otherwise be exposed within the box (not an exterior air barrier).
  • Heat compares to both electric flow AND light wave and radiant forms of energy, and so it needs both insulation and blocking or reflection.
  • Trainee Certification: Nonprofit "Residential Energy Services Network" (RESNET) approved the "Home Energy Team Institute" training in 2009, to train and certify home-energy auditors, as the first such training group approved by RESNET it offers its “Home Energy Survey Professional” certification to trainees; this is based on its National Home Energy Audit Standard (NHEAS) which provides the technical and procedural guidelines for various categories of home energy audits.
    • For information on RESNET’s insulation installation guidelines, see Bruce Harley’s article, “Insulation Inspections for Home Energy Ratings,” in the January/February 2005 issue of Home Energy magazine.[3]
  • One source of in-home comprehensive audits of the sort would be provided by HETI-certified auditors. HETI was founded in July 2008 and was an emerging service that had affiliates in eight states, including Pennsylvania, Wisconsin, New Jersey, Maryland, Iowa, Virginia, and Alabama, and in the District of Columbia. HETI candidates who earn RESNET certification are trained to consult with homeowners on energy efficiency improvements.
  • You could get some help with this at Home Depot online and at stores.[4]

Sources and Citations

  1. Energy Smart, Efficient Homes --
  2. "Navigating Energy Star’s Thermal Bypass Checklist", Oct 22 2010 by Martin Holladay, GBA Advisor,
  3. More information on RESNET’s insulation installation guidelines, Bruce Harley’s article, “Insulation Inspections for Home Energy Ratings,” January/February 2005, Home Energy.
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