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I agree the end product is only as good and sustainable as the design, in combination with it's technologies applied correctly. I believe that's what we are all commited to. There will always be different paths and priorities. I was sure that you were going to advocate the tent option and probably do prefer tents over living in a foamed house. Clearly my priority is the easiest path to high R-Value, sacrificing some petro chemical to save more petro chemical. I admit I also use I products like Grace Vicor, etc. in valleys, around openings, etc. to protect from water intrusion (with considerable attention to the drip path). I think these are good technologies (yes, not great - great Would be fool-proof), but they can be misapplied and as you stated - over applied, which could trap moisture, especially in combination, over large, adjacent surfaces. We use insulation baffles within rafter bays, which addresses this 'trapping' conflict, although a membrane breach will most likely go unnoticed. Nothing beats construction moving at a measured pace, with time to observe performance deficiences and make modifcations. Here's my regional argument. I believe that you live in Vermont. I live on Long Island. Fuel costs are much higher here. You can spec the less expensive, more environmental cellulose with half the R-Value, burn wood, save money and go skiing, while we struggle to pay off our excessively high real estate-valued lives. Looks like you took the right path based on the correct priorities. I am interested to know what you think the ideal thermal envelope consists of? Appreciate your postscripts. Dave SDR & Associates 131 Cedar Street East Hampton, NY. 11937 (631) 324-8868 (631) 324-0900 ~ fax On Mar 12, 2010, at 12:13 AM, Robert Riversong <[log in to unmask] > wrote: > --- 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