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Musings of an Energy Nerd

New Air Sealing Requirements in the 2009 International Residential Code

The latest version of the IRC gives you two options: comply with an air-sealing checklist or perform a blower-door test

Once local jurisdictions adopt the 2009 IRC, blower door technicians are likely to get very busy.
Image Credit: Martin Holladay

One of the most cost-effective ways of lowering residential energy costs is to reduce a home’s air leakage rate, so it makes sense for energy codes to ratchet up air-sealing requirements. The latest (2009) version of the International Residential Code does exactly that.

Just like the earlier 2006 code, the 2009 IRC includes a requirement (in section N1102.4.1) that “the building thermal envelope shall be durably sealed to limit infiltration.” The language in that section is unchanged; the code still requires that “The following shall be caulked, gasketed, weatherstripped, or otherwise sealed with an air barrier material, suitable film, or solid material:

1. All joints, seams and penetrations.

2. Site-built windows, doors and skylights.

3. Openings between window and door assemblies and their respective jambs and framing.

4. Utility penetrations.

5. Dropped ceilings or chases adjacent to the thermal envelope.

6. Knee walls.

7. Walls and ceilings separating the garage from conditioned spaces.

8. Behind tubs and showers on exterior walls.

9. Common walls between dwelling units.

10. Other sources of infiltration.”

New air sealing requirements, with two compliance options

In addition to these provisions, the 2009 IRC includes further air-sealing requirements in section N1102.4.2.

This new section gives builders two options: either the builder must comply with the requirements of an air barrier and insulation inspection checklist (Table N1102.4.2), and submit to a “visual inspection,” or the builder must show that “tested air leakage is less than 7 ACH when tested with a blower door at a pressure of 50 pascals.”

The checklist option

The items on the air barrier and insulation inspection checklist (see Image 2, below) make sense, although two provisions (the provisions requiring that crawl space walls and the corners of above-grade walls must be insulated) are vaguely worded and therefore ambiguous.

Here’s a partial list of the checklist items:

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  1. GBA Editor
    Allison A. Bailes III, PhD | | #1

    Georgia requires the Blower Door test
    It's nice to see the IRC join the IECC in the air-sealing requirements. The state of Georgia last year passed a new energy code ( that disallows the visual inspection to demonstrate compliance. Every new house must have a Blower Door test.

    As for who can do the testing in Georgia, they decided to keep it loose now. Builders can test their own work, but first they have to get certified as Duct & Envelope Tightness (DET) Verifiers ( It's a start.

  2. user-723121 | | #2

    State adoption of IRC
    Martin, I thought one of the conditions of accepting DOE Weatherization $ as part of the stimulus package was states accepting funds are required to adopt the latest IRC code. What is the timeline for state adoption of the 2009 IRC , what about 2012 IRC and IECC? I checked and they are showing about 2/3 of the states adopting 2009 IRC by 2015, sounds kind of pokey. We will have 2 new code cycles by then.

  3. 5C8rvfuWev | | #3

    More AHJ
    Allison Bailes said:

    "The state of Georgia last year passed a new energy code ( that disallows the visual inspection to demonstrate compliance. Every new house must have a Blower Door test."

    That's fabulous news for me as I'm planning to build here in GA.

    But earlier this year two new subdivisions opened locally for buyers in the $300k range. Given the market locally I wondered at the logic and imagined they were doing something "new" -- i.e., up my alley. They had their first open houses in late March, a finished unit and 3 more on the way.

    I left disgusted. They were big, and they were all framed and insulated -- without any sign of sealing either in the framing envelope or in the crawlspaces. These are, according to the code revisions Allison witnessed being passed, subject to the 2009 IRC.

    This week I plan to stop by the Planning Dept in the same county. While I'm there I think I'll stop by the Code Enforcement office upstairs to ask when their training will begin.


  4. EJ Palma | | #4

    As in the case of the TARP
    As in the case of the TARP money that was handed out to banks and was not accounted for, so goes much of the money from the Recovery and Reinvestment Act. Many cities around the country received the money without following the mandates, and follow-up supervision and accountability of the funds was lax. In response to Joe, I find your sarcasm regarding code officials a bit disconcerting. As a Building Official in the State of Connecticut (21 years), as well as a Designer and Builder (36 years), an accredited Green Professional with the NAHB, and presently achieving LEED accreditation, it is my opinion that one does not get the result they are looking for with sarcasm and negative criticism.. Joe do the Building Officials in your municipality approach you with a sarcastic, condescending attitude toward your projects, your training, or your certifications and intellect? If they do then they are not doing their job correctly as code officials, educators, and facilitators of the letter and intent of the codes. If they do not, then it makes one appear quite shallow and adversarial presenting a condescending attitude toward them. Primarily though, it does very little in promoting an integrated harmonious process between you and the officials of your local municipality. States are just catching up on the training aspects of the new IRC 2009 & 2012, IECC 2009 & 2012. Building department budgets for code books and training facilities have been devastated by the economy. Adoption of the codes is always behind schedule, and in many instances reactive as opposed to proactive. That is no excuse for any of us not understanding the technical aspects of our jobs. Besides being a builder, what are your credentials? The ICC has offered free training for the IECC 2009 in all states, have you taken it? They even give you a copy of the code book and workbook. Instead of the "sheesh", if you already have not done it, you would be better served to educate yourself in the ICC family of codes. Also maybe you should get accredited in the field of green building through USGBC or the NAHB or one of the many excellent local grass roots organizations found around the country. That would be something "new" and up your "alley". At that point you would be able to speak from an "educated" platform instead of one without any intellectual foundation except negativity and criticism.

  5. davidmeiland | | #5

    Washington State reqs
    Washington has its own energy code, modeled on the IECC. The airtightness requirement is not volume based (ACH) but is derived from square footage of floor area. It sets the bar at *roughly* 5 ACH50 for a house with 8-foot ceilings, but houses with higher ceilings get a break because their volume is larger for a given footprint.

    I need to check back and see what the AHJ here is requiring as to who does the test. It may be that a builder can self-certify.

  6. 5C8rvfuWev | | #6

    reply to Edward Palma
    You asked:

    "Joe do the Building Officials in your municipality approach you with a sarcastic, condescending attitude toward your projects, your training, or your certifications and intellect?"

    Not at all, Edward. Nor would I ever speak that way to them. On the other hand, I wasn't talking to them but expressing my chagrin that they apparently accepted these traditional (in the sense of inadequate and outmoded) buildings without a fair-thee-well ... nor upgrades in any area. But I will inquire, as I said, because I want to enthusiastically support the direction of the code changes (in case they've been running into reluctance or resistance), and I want them to know that a resident of the county who wishes to build a new home is eager and anticipating the progress which only THEY can assure.

    I never said, nor meant to imply, that they have an easy job of it. I know better.

    In the interest of disclosure, Edward, I'm sorry if my comment was misleading ... I'm not in any sense a pro -- I'm here at GBA as a consumer with just the learning attitude you suggest I should have. And while I'm not a contractor, or anything more than an amateur who has muddled through other home building adventures, I think as a consumer (and taxpayer) I'm in an ideal position to support, encourage, and even be a little insistent that steps be taken to insure progress and responsible environmentalism ... as specified by code.

    I apologize if my comments seemed to dismiss the problems or difficulties of officials or anyone else in the trades as I have nothing but admiration for the skill and knowledge y'all have to be successful. All the same, in my own career I've never been given a "pass" just because I found it hard to adapt to new technology or methods or standards.


  7. GBA Editor
    Martin Holladay | | #7

    Response to Doug McEvers
    Your impression is basically correct. The energy efficiency funds that were part of the stimulus bill were handed out with the understanding that states would adopt the 2009 IRC, but there really weren't any teeth in the legislation.

    The last time I wrote a blog about energy codes, Mike DeWein commented on the issue. “We know that some states have adopted the code but have done nothing to ensure implementation,” said DeWein. “There were great amounts of money in the Recovery Act for energy efficiency — funds that were handed out to all the states. They all took that money. While there wasn’t any great set of teeth to the Recovery Act preconditions, it was understood that the states were supposed to adopt the 2009 code and meet compliance goals by 2017."

  8. davidmeiland | | #8

    The building inspectors here were able to get a day's worth of training on the new energy code requirements, including blower door testing, courtesy of Washington State U's energy program, which has done the same thing many other places in the state. While I agree they should know the latest and greatest, I do not envy them the task of trying to educate builders and others on how to build better buildings. I find myself in that position sometimes now, and there are a lot of guys out there who don't want to do anything differently, no matter how easy or important it is.

  9. Ted Clifton | | #9

    Inspectors, Builders, and other Blind and Broke parties
    I have been teaching classes for the last year and a half on how to comply with the new codes here in Washington State. To date, only a handful of builders have taken the classes, and even fewer code officials. The problem seems to be two-fold; most builders don't have a new home to build right now, so the codes are strictly academic, and the local jurisdictions don't have the funds to send what staff they have left (which is less than half what they had two years ago) to take the classes.
    Many builders seem totally unaware that there have been changes to the code that will significantly impact they way they do business. Whenever the economy starts to turn around, and builders start building homes again, I expect to see huge (but hopefully ineffective) push-back on the new blower-door requirements, and many other elements of the new codes. For now, ignorance seems to be bliss.

  10. user-723121 | | #10

    Air sealing for fun and profit

    I have a different take on the new housing slowdown and the adoption of more restrictive energy codes. More and more I see the large production builders offering energy efficiency packages for new homes. The market is so tight and buyers so fickle, energy efficiency is viewed as a marketing advantage. If new home buyers equate efficiency with quality construction this puts the builder in a stronger selling position.

  11. Ted Clifton | | #11

    Marketing advantage, or lip service?

    I see the same thing you do, almost. I see the big builders paying lip service to energy efficiency, while continuing to do what they always do best, build the same old stuff for the lowest possible cost. I will grant you that there are a select few big builders doing an outstanding job of cranking out very high quality, very energy efficient homes, but these are the exception, not the rule. We have not yet done a good enough job educating homeowners on what they should be able to expect in the way of energy efficiency to really see that change.

  12. user-979382 | | #12

    codes & air barriers
    Professional code officials understand that educating the public is as much of a responsibillity as educating staff'. Builders will cooperate willingly if they're 1)given time to adjust pricing and contracts and train trade partners, 2)able to pass increased costs on to consumers, and 3)not subject to unnecessary delays. These are reasonable expectations, and code officials can facillitate them all. Testing of systems, and the authority to set the testing conditions and other requirements, are settled policy familiar to building inspectors in most places, and the disincentives for providing fraudulent test results are substantial. Traditionally, the one-time owner-builder is a much more problematic player than professional contractors.
    Forrest Fielder, CBO
    Phoenix, AZ

  13. user-621079 | | #13

    Code required blower door tests (and duct leakage tests)
    All, Good string of comments on the state of IECC 2009 code adoption and enforcement. Since 7ACH50 is the (huge, except in the case of very small houses.) leakage metric, someone has to figure out the accurate volume of the house that's being tested. Personally, that's no easy task for lg custom homes w/ vaulted ceilings, dormers and so forth. Is the basement or conditioned attic volume included? As a rater, I follow RESNET guidelines, but what about those doing testing that don't know the guidelines. Also, Don't forget the 09 also requires duct testing when any portion of the ductwork is outside of conditioned space.

  14. T.C. Feick | | #14

    The code compliance path does not fork, sometimes.
    First, I think that the testing option should be the only option. Few things impact energy efficiency as drastically as air sealing, and none as effectively for the dollar spent. The fact is, even in high enforcement areas, such as mine (southeastern Pa), Chapter 11 is not fully enforced. For instance, If ducts are installed in non-conditioned space, R-8 ductwork is required and so is a duct blaster test (N1103.2.2 #1.) I have seen the R-8 ducts, but I talk to a lot of builders, inspectors, and building performance specialists in the course of a day, and testing is not widely enforced. So, if enforcement is stepped up on at least thes homes with ducts in attics, basements or crawls, then I see this as the perfect opportunity to sell the testing path of the envelope (blower door) as the proper equipment will likely already be on site. This is probably the single most important item in the IRC that can affect real change to building performance. Once builders get used to air leakage testing, the 7ach50 number can be revised downward. Visual inspection will never be able to do this.
    Secondly, as a point of clarification to an earlier post, New York does not adopt IRC in its entirety, but publishes their own statewide building code (through ICC), which looks a lot like IRC for residential construction.

  15. SMPGtFBWTq | | #15

    Blower door test washington state
    There is a lot of good information on this site but for someone like myself that wants to do some of his own work building a house it all sound like a catch 22. You have to hope the person you get to do the blower door test (if you can find one) wont gouge you because you are completely at their mercy. It is in my best interest to build a sound cost effective house but having to depend on a certified technician that is also in the business of charging you to “fix the problems” is like the fox watching the hen house. From what I can see in Washington state the fees for test range for 75$ plus 50$ per hour to fix problem to 250$ to set up the test, and to fix the problems with rates up to thousands of dollars. Its like the State of Washington is more interested in looking like they doing something rather then adjudicating the problems with the millions of older housing that are leaking heat like a screen door i.e. an academic 2 dimensional solution to a 3 dimensional problem. It’s new construction and ultimately the new consumer that will pay the bill.

  16. GBA Editor
    Martin Holladay | | #16

    Response to Frank Keeler
    Although it's certainly possible to build a house without conducting a blower-door test, such houses are usually leaky and expensive to heat and cool. Investments in air sealing and testing ultimately pay for themselves in lower energy bills.

    In many parts of the country, the cost of blower-door testing is subsidized for builders enrolled in the Energy Star Homes program. In some areas, blower door tests are free for Energy Star builders. You should contact your local Energy Star Homes program representative to see if such subsidies exist in your area.

  17. SMPGtFBWTq | | #17

    Cant budget for cost
    My wife and I have decided not to apply for a building permit at this time thank you all for your input but because of the uncertainties of the law and our inability to budget for the costs we just can not go forward. From what we can gather the cost for the blower door test is between 150 and 500 per test but there is no limit to how many times we will have to have the test to comply 1, 2, 5 no one can say. Then there are cost for foam caulk tape to seal and labor to seal every crack according to the state of Washington’s new energy code 502.4. plus the upgrade of all doors and windows the uncertainties of cost is just to great. The project is scary enough with out the thought of spending weeks and thousands of dollars on test after test its all to much. This to me signals the end to the owner / builder because of the inability to budget for ramifications of unforeseen number of tests.

  18. GBA Editor
    Martin Holladay | | #18

    Response to Frank Keeler
    Like you, I am an owner/builder. To build a house, you either have to learn certain skills -- mixing concrete, rough carpentry, roofing, and air sealing -- or you have to hire a contractor who has those skills. And yes, you have to budget for all of these things.

    If your budget isn't quite large enough for a home-building project, that's perfectly understandable. But the problem isn't the blower-door test. After all, the blower-door test is designed to help you lower costs, because the test will result in an energy-efficient building that will save you money for years.

    Perhaps you can design and build a smaller, more affordable house. If you do, be sure to build it tight! You'll be glad you did.

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