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Community and Q&A

Which SIPs for roof: 10 1/2 in. vs. 12 1/2 in. for performance?

Claire Anderson | Posted in Energy Efficiency and Durability on

We’ve been quoted an additional $1,460 to “upgrade” to 12.5-inch roof SIPs and are wondering if the additional investment is “worth it.”

I’ve always heard that the more insulation you have in your ceiling/attic, the better, but I’m wondering if that $1,450 would be better spent on other energy-efficiency measures.

Thanks,
Claire

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Replies

  1. GBA Editor
    Martin Holladay | | #1

    Claire,
    It's certainly true that "the more insulation you have in your ceiling/attic, the better."

    Whether the upgrade is a cost-effective investment depends on your climate and the cost of alternative measures. A HERS rater or energy consultant should be able to help you optimize your investments in your building envelope and HVAC system.

    You will get better advice if you tell us where you are building.

  2. Claire Anderson | | #2

    Hi Martin ~

    We're building in the Applegate Valley of southern Oregon, latitude 42.26; longitude -123.19, elev. 1,480 ft.

    Here's a quick HDD analysis:
    Description: Farenheit-based heating degree days for a base temperature of 65F
    Source: http://www.degreedays.net (using temperature data from http://www.wunderground.com)
    Accuracy: No problems detected
    Station: Sorensen's Ranch, Applegate, OR, US
    Station ID: KORGRANT8

    Month starting HDD
    8/1/08 108
    9/1/08 192
    10/1/08 409
    11/1/08 595
    12/1/08 889
    1/1/09 850
    2/1/09 668
    3/1/09 652
    4/1/09 544
    5/1/09 324
    6/1/09 151
    7/1/09 147
    8/1/09 298

    Description: Farenheit-based cooling degree days for a base temperature of 65F
    Source: http://www.degreedays.net (using temperature data from http://www.wunderground.com)
    Accuracy: No problems detected
    Station: Sorensen's Ranch, Applegate, OR, US
    Station ID: KORGRANT8

    Month starting CDD
    8/1/08 245
    9/1/08 175
    10/1/08 37
    11/1/08 0
    12/1/08 0
    1/1/09 0
    2/1/09 0
    3/1/09 4
    4/1/09 32
    5/1/09 105
    6/1/09 122
    7/1/09 338
    8/1/09 249

    Thanks,
    Claire

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