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Community and Q&A

What is better to use, foam in the exterior walls or go with Blow-In-Blanket (BIB) insulation?

sRpHrL8a6C | Posted in Green Products and Materials on

We are building a home near Dallas. We are using 30# felt as the housewrap w/Brick construction and Demilec Sealection 500 open cell foam in the attic. We are trying to decide whether to use the same foam in the exterior walls or go with the Blow-in-blanket (BIB) insulation. Do you have any recommendations? Also if you any other thoughts for the attic as it relates to the use of spray foam (or if any other products are better and safer), please let us know. Thanks.

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  1. Billy | | #1

    Spray foam will give you superior air sealing, and closed cell foam provides a vapor barrier that may be important, particularly in the attic. Plus, closed cell foam has a higher R value per inch that will be put to good use in the attic.

    If you are trying to save money you could spray a couple of inches of closed cell foam in the walls and then use BIBS for the rest.

    In our last house that is a mixture of old and new construction we used 4-5 inches of closed cell foam in the attics, closed cell foam filling existing 2x4 stud bays, and a combination of 2-3 inches closed cell foam and BIBS in the 2x6 walls. In a cathedral ceiling area we added cross strapping under the rafters and BIBS under the spray foam with the Insulmesh stapled to the cross-strapping. And an ERV. Comfy.

    Others will chime in with more specific advice for the Dallas climate.


  2. GBA Editor
    Martin Holladay | | #2

    Any type of insulation can work well, as long as the wall assembly and the ceiling assembly are well designed, attention is paid to airtightness, and the R-values are adequate (equal to or exceeding minimum code requirements).

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