There are few building theories I can accept as absolute gospel. While I understand most of them, I often find the theories cannot fully explain the range of problems I see in the field. Some theories are expressed in black and white, while real situations are often a matter of degree. Theories, by necessity, are simplified, while reality is complex: Often a variety of forces are at play and interact in ways the theories don't predict. For example, theories of convection, vapor diffusion, and condensation are undoubtedly useful in explaining observations made in houses and attics, but some of the symptoms I've observed still leave me perplexed. A variety of observations I've made have led me to supplement the