--- On Thu, 3/11/10, Samuel Robins <[log in to unmask]> wrote:
You site only extremes. Life has compromises. The perfect is the enemy of the good. You could debate every position and forever be confined to a tent.
The examples I give are legion, hardly extreme. In fact a central element of the CNRC MEWS study, as well as the Florida Solar Energy Center study (two very mainstream groups) was to introduce the inevitable minor leak into wall or roof assemblies. In both cases, foam-insulated or foam-sheathed envelopes got failing grades.
Yes, the perfect is the enemy of the good. Which is exactly why I draw attention to the absurdity of the "perfect wall" such as Joe Lstiburek and many others advocate. An impermeable foam plastic box performs only as long as the building starts out perfect and remains perfect for its useful life. Neither case is either likely or reasonable to consider.
The most foolish approach to any technology is to try to make it "fool-proof". What is required for durability and the health of its occupants is to design and build a house to be "fail-safe". All human artifacts fail, and most begin their lives with inherent flaws. A resilient structure can tolerate minor failures. A non-resilient structure cannot. 
In a house assembly, resilience requires materials and methods which allow a structure to dry when it - inevitably - gets wet, and to buffer (absorb and release) excessive humidity when the mechanical systems meant to control it either are overwhelmed, under-perform for lack of maintenance, or go down when the power grid crashes.
Building hermetically-sealed boxes and calling them homes fit for human habitation contradicts basic physics, undermines biological integrity and defies common sense.
- Robert Riversong  master housewright, building scientist, philosopher and prophet for our times