Video: How the 'Perfect Wall' Solves Environmental Diversity

Originally published by the following source: Applied Building Technology GroupAugust 29, 2018
by Timothy Ahrenholz


Around the world, people build dwellings in all kinds of environments.  Even in just North America, there exists a great diversity of climates, ranging the gamut from hot to cold and dry to humid.  Wouldn’t it be nice if there were some way to design an enclosure that can perform well in any of these conditions? 

Well, there’s good news!  There is a wall that can get the job done.  Sometimes called the “perfect wall,” this design puts all the control layers (for temperature, moisture, air, and water vapor) on the outside of the wall, thereby protecting the structure.  The only variable for this design is the thickness of the exterior continuous insulation. 

To learn more about this technique and about building envelopes in general, check out the resources on, and in particular, this article delving into the perfect wall concept.  Also of interest is this short video describing the environmental diversity of North America, part of a series on the perfect wall:



Here are other related videos:

  1. Fear Building Envelopes No More with This Website & Videos
  2. Thermodynamics Simplified Heat Flows from Warm to Cold
  3. Moisture Flow Drives Water Induced Problems

For relevant research reports and general assistance on this topic, please visit these pages on

  1. FSC Wall Calculator
  2. Steel Wall Calculator
  3. Commercial Walls Resources
  4. Residential Walls Resources