A core concept in high performance building is to create a strong thermal barrier between the inside and outside of a home. Building materials at exterior walls therefore need to include products that offer thermal resistance – in other words, insulation. The problem is finding insulation products that are efficient, cost effective, sourced from sustainable materials, and are safe. Asbestos performs well, is relatively inexpensive, but poses serious health risks to humans. Spray polyurethane foam (SPF) has been specified and recommended on a number of high performance projects, however, as we are learning, it poses serious risks of its own.
BuildingGreen.com, Treehugger, and others have written in the past about toxic emissions produced during application (the EPA is currently evaluating that issue), as well as the decidedly non-green aspects of SPF (“greenhouse gasses”). There is now clear evidence of an even more serious threat that will certainly impact production building: SPF insulation, improperly applied creates an exothermic reaction that can result in fire. Here are comments from Tristan Roberts of BuildingGreen.com:
But when SPF is implicated in building fires, it really turns my head! We’re talking not about more vague, statistical likelihoods of future risks–we are talking about lives and property being endangered or lost in the moment. We wrote about that last year in the context of an effort by a fire marshals group to get the word out about unique fire risks from green building. That article referred to the tragic fire at the Alstonvale Net Zero House in Hudson, Québec, which occurred immediately after SPF installation, and reduced an almost-completed home to rubble.
The search for a sustainable, energy efficient, cost effective and safe insulation product continues.
I encourage you to read the full article which includes links to several resources regarding this very serious issue.
AEC Forensics 