We already installed Quadfoam 2.0, a "two-component, 2 lb., closed cell, spray applied, rigid polyurethane foam system" under the roof of our house, between the rafters. We read the manufacturers product safety documentation and it appears that the final product is safe, although the individual components have issues. We did not notice any respiratory symptoms spending time at the house, and by visual inspection the material appears to have been installed correctly. On the other hand, the EPA assessment of the material is not completely reassuring, because they say that, "The potential for off-gassing of volatile chemicals from spray polyurethane foam is not fully understood and is an area where more research is needed." (see http://www.epa.gov/saferchoice/potential-chemical-exposures-spray-polyurethane-foam#long-term). There is also a scary post on Treehugger.com about people ruining their houses. http://www.treehugger.com/green-architecture/losing-their-health-and-homes-spray-polyurthane-foam.html
If we had done this research before installing the product we probably would have used another material, but now that it is in place we are wondering
Is it fine to keep the insulation in place, and perhaps install some attic venting so that if any minor off-gassing does occur it will not make its way into the living areas of the home?
If we want to get rid of it, can we just scrape it off the rafters and roof sheathing and replace the ducts and wires that it is sprayed to, or will this leave a residue of possible toxins, so that the only solution is to replace the entire roof?
A couple of years later...Just want to put some information up here in case other people have doubts about the product. We had the house tested by an environmental consultant and they convinced us that there was Zero off-gassing from the foam. And the house is insulated amazingly well. So I would say that it was a good product and would recommend it. The caveat is that if it is improperly installed it can really be a mess, because there are truly nasty chemicals present in the two components that are sprayed separately to create the final product. If the intended reaction does not occur between the two components when they are sprayed into your house there can be off-gassing which could make the house uninhabitable. I think that this very rarely happens, but make sure that your installer really knows what they are doing, because the risk is there! Also, make sure that you stay out of the house when the foam is curing, because otherwise you could develop a sensitivity to the chemicals that are present which would exacerbate any problems due to off-gassing. This is a danger for installers more than homeowners. A couple of other points: The insulation is so effective that in California, if you spray the underside of your roof then the attic is considered "conditioned space", so it would not be vented like a normal attic, and it would also not be separated from the rest of the house by any kind of vapor barrier. Also, my idea of scraping the finished spray foam out is Impractical and not a solution if there is off-gassing. Whenever you mess with the spray foam you are exposing uncured areas and so if there's a problem with off-gassing it would make it worse.