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Hi Glenn, During the 35 years that I've actively remodeled houses (with breaks to try to find something that payed better and didn't involve blood loss,) I've come to the conclusion that only soundproofing is more poorly understood than insulating. I don''t mean that it's like the electrical field where specific, accurate information exists but is poorly understood by non-professionals. My experience leads me to believe that even the so-called experts usually have a poor grasp of the technical aspects of insulation. Whether reading articles or books about it, or talking with insulation contractors, you always get a certain amount of contradictory information. A major example would be the issue of super-insulated houses which were considered state of the art in the late 70's and early 80's. After a great number of them had been built or retrofitted, it was discovered that insufficient allowance had been considered for air exchange, and the air inside a super-insulated house would soon become unhealthy just from living in it. Before (expensive and relatively inefficient) heat retaining air exchangers were developed for (expensive and relatively infuriating) retrofit, some utility companies and insulation information experts recommended that the occupants of a super-insulated house simply open an exterior door every hour of so, letting the contaminated heated air out, and replacing it with clean unheated air. See anything wrong with this picture? Later, it developed that the previously disputed subject of where and how to install the vapor barrier, or barriers, had, in many instances, resulted in waterlogged insulation and rotting framing members---two conditions that owners of newly constructed or recently remodeled houses probalby wished they hadn't paid extra for. Then there's the dismal, but equally disastrous episode concerning the toxicity of polyurea formaldehyde insulation, at one time hailed as a miracle of inexpensive, high R value blow-in retrofitting (and new mobile home construction.) You don't have to be a student of construction history to see that insulation information leaves a lot to be desired. You can demonstrate it to yourself using simple arithmetic. Most of the time I was involved in residential remodeling, fiberglass batt insulation was rated at R-11 for 2X4 framed walls, R-19 for 2X6. A previous poster stated that the values are now R-13 and R-19. Different materials and different forms of the same material have always provided different R values, but if batts for 2X4 channels went from R-11 to R-13, shouldn't the same insulation for 2X6 channels have gone from R-19 to R-22.5? More fundamentally, how was it that batts of a material would provide a value of R-11 when fit snugly in a 3.5 X 14.5 channel, but R-19 when fit snugly in a 5.5 X 14.5 channel? Where did the extra R-1.7 come from? (Do the math.) If there's some benefit from the configuration of a 2X6 framed wall relative to a 2X4 framed one, why does the value stay at R-19 whether the 2X6 wall is framed 16" O.C. or 24" O.C.? I'm not trying to make a case here, just give a hint of the amount of misinformation, and the bottom-line lack of solid information that seems to plague this field. So, good luck, Stan
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