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Fighting the inspector- double stud wall NOT “ci”!

Jesse Lizer | Posted in Building Code Questions on

This is how great building officials can be. I am working on getting my project qualified with the HERs raters and Energy Star programs to qualify for new construction rebates from local utility companies. However the inspector is claiming a double stud wall does not comply with IECC 2009 since it does not have r5 ci / 13 cavity as well as r5 ci at the box sills. I am trying to explain to him the double stud wall achieves the same thing ci does, not to mention my walls are roughly r40 overall. They also will not allow REScheck to prove compliance (36% better) since I am going after a Level 2 Energy rating (5% better then ES 3.0). “Code is code” was his response when I said “so I would pass if my wall had half the performance”.

Any thoughts from the fine folks here?

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  1. John Brooks | | #1

    Seems like you would qualify for
    402.1.4 Total UA Alternative

  2. GBA Editor
    Martin Holladay | | #2

    Maybe I'm being slow -- but what does "CI" stand for?

  3. John Brooks | | #3

    I think he is talking about Insulated sheathing ...
    perhaps Continuous Insulation

  4. Expert Member
    Carl Seville | | #4

    CI - Continuous Insulation. Took me a second myself

  5. Expert Member
    Carl Seville | | #5

    Damn, John, you beat me by about 1/2 a second on that one.

  6. GBA Editor
    Martin Holladay | | #6

    Here's some relevant information from one of my blogs:

    "The code makes no mention of double-stud walls, so builders who choose this method of construction will need to convince their local building official that a double-stud wall complies with the code. Here’s one way to make the argument:

    To comply with the R-20 plus R-5 requirement, some of the insulation — at least R-5 worth — must be continuous. That means you need at least 1.5 inch of cellulose between the two rows of studs, implying that a double-stud wall needs to be at least 8.5 inches thick.

    Since 8.5 inches of cellulose has an R-value of R-31.5, the total R-value of the wall exceeds the R-20 plus R-5 requirement.

    In conclusion, any double-stud wall that is at least 8.5 inches thick appears to comply with the R-20 plus R-5 requirement."

    More info here: An Overview of the 2012 Energy Code.

  7. David Meiland | | #7

    Jesse, don't know if this will help, but you could get ahold of one of the energy code specialists at Washington State University Extension's Energy Program and ask them how to phrase your explanation to the inspector. They are very current on code interpretations and no doubt this issue has come up before. If you Google their site there is a phone number with actual people who answer it just for stuff like this.

  8. Danny Kelly | | #8

    Can't you just do a RESCheck and give that to him?

  9. John Brooks | | #9

    remember.... the inspector is your friend...
    don't think of this as a FIGHT
    remain calm

    Serenity now, Serenity now

  10. Doug McEvers | | #10

    I built a house in Prior Lake, MN in 1989, my first there and had an insulation inspection scheduled. The framing inspection was performed by the regular inspector and the insulation was as I found out, inspected by the head building official. He walked in the house, it was a double stud wall with continuous 8 mil Teno, lapped and sealed, looked around for a short time and said "outstanding". This was my first encounter with this inspector and it was a memorable one, we were on great terms after that.

  11. Jesse Lizer | | #11

    thanks everyone for the feedback. "Fighting" really is not the correct word I guess, maybe scholastic debate would be better? :)
    I talked with him again this morning. I am not sure he really inspected the plans the first time around as this "debate" was of a different tune. I explained to him the IECC section stated about, as well as Martin's comment about the ci between the studs (3"=about r12). I also said I am 36% better then REScheck. This made his eyes widen. He said ok, well your walls are fine, but he still had an issue with no ci at the box sills. Again, he did not look at my enlarged detail showing my layers (sheathing, 1" XPS, rim board, floor structure) on areas that are single story and 2 story I have the floor structure bearing on the interior 2x4 wall and the trusses on the exterior wall.
    He said to be honest he has never seen anything like this before so he was not sure how to approach it. Apparently not approving it was the option he settled on....
    But all is well now. He said it looks like a wonderful design and they look forward to seeing it built.

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