Foam-Free Wall Assembly

Guidelines by Climate Zone

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.

Climate Zone Map

Wall Assembly Chart

Control Layer Chart

4. Email us and/or phone us with questions.


  • 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 out why service cavities are uniformly suggested, here.

Happy foam free building!


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