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Foam-Free Wall Assembly Guidelines by Climate Zone

December 7, 2012

Spanning eight climate zones, from very hot and humid to subarctic, and desert to rainforest,  the US presents widely varied demands on our building enclosures.    Anecdotally, there is much written on assemblies in cold climates but not so about hot climates.  And most of the literature today assumes foam will be the primary strategy for achieving a high performance.

But if you are no longer convinced that foam is the optimal strategy for making sustainable building or a sustainable environment (See, Foam Fails).   What then?  There is relatively little written in a comprehensive manner about high performance assemblies that are foam free in the US.   This blog is but one small attempt to help fill this general void of information – starting with wood construction wall assemblies.

Wherever your project might be, it would be nice to at least start with a set of suggested foam free assemblies that you can then customize to your particular project needs.   This is what these four steps attempt to do.

  1. Find your project location and climate zone on the US Climate Zone Map.  (NOTE: Climate Zones are on the move due to global warming – and may be appropriate to consider.)

    Climate Zone Map

  2. Find the group of assemblies suggested for that climate zone on the Foam Free Wall Enclosure Assembly Chart.

    Wall Assembly Chart

  3. Find descriptions of the basic control layers on the Control Layer Legend.

    Control Layer Chart

  4. Email us and/or phone us with questions.  Contact information is here.


    • Yes, these are by definition, oversimplifications.  It is up to the project professionals to develop the the complete details and specifications appropriate to the specific project, to ensure a robust assembly.
    • Micro-climates, orientation and shading need to be considered. Climate zones are generalizations and thus these charts and notes are solely meant as conceptual starting points for project specific details.
    • Find out why back-vented rainscreens are uniformly suggested, here.
    • Find our why service cavities are uniformly suggested, here.

Happy foam free building!


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2 Responses to Foam-Free Wall Assembly Guidelines by Climate Zone

  1. Paul Dowling December 8, 2012 at 9:46 pm #

    Thanks for a very helpful set of guidelines. Hopefully you can add a link to a Canadian climate zone map for your northern neighbours at some point.

  2. foursevenfive December 10, 2012 at 4:40 pm #

    Paul, you can use this map as a general reference –

    Zone A – being equal to US climate zone 4c

    Zone B – being equal to US climate zone 5

    Zone C – being equal to US climate zone 6

    Zone D – being equal to US climate zone 7 and 8*

    On the pacific shores it can locally be somewhat milder. This climate map of Alaska will give you an idea – http://pubs.usgs.gov/ha/ha730/ch_n/gif/N002.gif

    And similar to the USA from west to east, after the rocky’s – it goes from dry to humid.

    And yes, we do ship to Canada. Airtight construction gets more and more important when it gets colder and colder – as well as having a vapor open exterior…

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