A representative of the industry says I shouldn’t be picking on fiber glass. He’s right.

This TreeHugger used to complain a lot about fiber glass insulation, but much has changed over the last few years. I recently wrote Over half the new homes in the USA are insulated with fiberglass batts where I ate some of my earlier words and noted:

My main complaint about it was that “nobody understands how to install it properly to minimize air leakage or wants to spend the time and money doing it.”

I then received a long and thoughtful response from Angus E. Crane of the North American Insulation Manufacturers Association (“NAIMA”) who had issues with the post. He starts by noting that, “in order to achieve intended thermal performance, all forms of insulation must be installed properly. That is why NAIMA strongly supports energy codes and standards that either promote or require Grade I installation for all batts.”

Totally agree – if installations were all Grade I there would be no issue here. But Mr. Crane is absolutely correct in noting that poor installations happen with every kind of insulation, not just fiber glass. My emphasis on his most important point:

Indeed, we have complained often about spray foam because of installation problems, health issues, embodied carbon and fire hazards during and after installation. Crane writes:

Mr. Crane notes that the cellulose beloved of green builders can also be problematic:

He also reminds us that cellulose can be a fire hazard if improperly installed around pot lights and furnace flues, a worry we share. Mr. Crane concludes his letter:

© Ready for loose fiberglass insulation/ Lloyd Alter

He’s absolutely right. I have seen terrible foam installations and beautiful fiber glass installations, like this blown installation being done by Hammer and Hand in Seattle a few years ago. Ten years ago I thought fiber glass insulation was fundamentally problematic, but they have fixed that by switching from formaldehyde to acrylic binders, while at the same time we have learned about the problems with other insulations. Fiber glass is the least expensive insulation, so it makes sense that it’s the one chosen most often when builders want to build quick and cheap. But it is a fine product when used properly.

I will be taking Mr. Crane’s advice and will be an equal opportunity whiner about installation quality, whatever the insulation is.