Bill Christensen recommended a preformed block called Faswall made with wood chips. Does anyone know what the binding material is? Persons with Chemical Sensitivities can not tolerate pressboard or plywood because of the binding glues which contain formaldehyde and other chemicals which outgas during the entire life of the product. Concrete block is tolerated well by all people with MCS as it is fairly inert and only needs to be sealed against concrete dust and this can be done with whitewashing. Concrete block also "breathes" and filling the concrete blocks with sand makes it a good thermal mass. I do not believe cinder blocks are manufactured anymore, though I remember them from my childhood. Cinder blocks were a dark grey color with sharp black "cinders" embedded in it, an almost glass-like material.
