What shall I stuff my house with?

There isn’t a handy metaphor that springs to mind, regarding the marrow that is missing from the bones of the  house. Actually, that one’s not that bad. The point is, this old house right here needs some stuffing in its walls! It just isn’t Thanksgiving without a good dollop of stuffing, dontcha know!

Now the question is what to put in the walls. I thought about what the energy rater had said on the matter– at one point he’d mentioned cellulose, sprayed with borax, as a recycled material that could be used. But later on, he mentioned spray foam. In fact, he mentioned a company with “Spray Foam” in its name. Were these the same thing?

Nope. There are several different kinds of insulation available. There’s the classic fiberglass, or “glass wool” as our friends on the other side of the pond would call it. There’s cellulose, mentioned above. And spray foam is a different animal altogether, made from polyurethane. Then you start getting into some crazy stuff: actual wool, for example. Or recycled denim, because hey, shouldn’t your house get to wear pants too?

This is getting complicated. Other factors aside, first let’s ask, how do you know which material is the most effective insulator?

Well, it looks like each material type is given an “R-value,” often measured in terms of per inch. As this FTC.gov article explains, R-value means “resistance to heat flow.”  And here’s another article from los federales, specifically the Department of Energy, that provides an overview of different insulation materials and gives some general R-value ranges. It’s kind of long and not as bullet-pointy as you might prefer.

But you’ll also want to know the total R-value your house needs. Maybe you need a total resistance of 40 in your attic. That would mean needing over 10 inches of an insulation type rated at 3.8 per inch. Or eight inches of an insulation type with an R-value of 5. If the R-value is lower, just add more of the shit in, I guess.

To take a stab at the total R-value you’d need, the government once again comes gallivanting to the rescue. Who would have thought they’d be this fucking helpful? Check out this chart from Energy Star.  Actually, I’m going to grab it and put it right here:


What zone do you live in? It ranges from zone 1 (if you happen to live in Oahu or the reservoir tip of Florida) to zone 8 (if you’re living in some godforsaken place like Nome, which is in a zone one higher than most of Alaska. Think about that for a moment).

I happen to live in southern Maine, part of zone 6 (slogan: “At least we’re warmer than Alaska! And much warmer than Nome, Alaska!”). So the chart recommends, for our (pretty much) uninsulated attic, a total of R49 to R60. And for the walls… well, it’s a little unclear, because I don’t think siding needs to be removed in our case, but maybe R6?

“Okay,” you say, “so just find the stuff with the highest R-value and then you’ll need the least of it to meet your house’s R-value requirements. One and done. Let’s go have a sandwich.”

Yeah, I could go for a sandwich right now. I surely could. But there’s a couple of other questions to ask here about insulation types. The first is cost. Is cellulose more expensive than spray foam, or vice versa? What about the exotic “denim” option? This is a difficult question to answer. One I probably won’t be able to answer until I talk to a couple of the names on the list that Paul Button provided me.

But how about a question we can start to answer: what type of insulation is friendliest to the environment? I.e., is not causing the Earth to burst into toxic flame?

Yes, insulating your house is a “green” action. Congrats. But if you stuff it with dead babies sacrificed on an altar to Walmart, how helpful is that, really? What kind of potential environmental impact does the material itself have? And what kind of effect on the planet did the process of making the material have?

Let’s ask a cellulose manufacturer which material is best for the planet! The answer is… cellulose! Okay, maybe we can try for a less biased examination. Let’s ask “Mother Earth News,” obviously. (Here is part of the problem with advocating for the environment: some of the most dedicated organizations have silly fucking names.) Another vote for cellulose; denim is manufactured using pesticides, and wool is too expensive.

Still biased? How about a piece from BuildingGreen.com called “Avoiding the Global Warming Impact of Insulation.” They’ve done some research and put together a table (based on limited information from manufacturers) that I will steal and put here:


The key number is in the rightmost column, a number they’ve called GWP, or “Global Warming Potential.” Comparing cellulose, fiberglass, rigid mineral wool (whatever the fuck that is), and several types of spray foam, they conclude that cellulose has a far lower GWP than any of the others. And give a big thumbs down to both extruded polystyrene and spray polyurethane foam blown with hydrofluorocarbons (HFC, a greenhouse gas).

If you used one of those two latter types of insulation, it’d take many years for the actual home insulating provided by the materials to offset the environmental damage caused during their production.

“Well, screw BuildingGreen.com,” you say. “I want to hear what Bob Goddamn Vila has to say on this topic.”

All right, let’s traipse on over to ThisOldHouse.com. Their conclusions as follows: Cellulose is better than fiberglass for the environment and just as effective. Though they give a pass to fiberglass. Cotton and wool are good to avoid allergens, they say. And then they give kind of a pass to the foams if they don’t use an HFC blower. Actually, they don’t really come to any conclusions at all. Thanks a lot.

And “How Stuff Works” gives top marks to something called Icynene, a spray foam made from castor oil– even though it costs three times as much as fiberglass and requires a ventilation system! Thanks a lot, ya fucks!

Well, looks like I’ve got to make some calls. Not just to weatherizers and insulators themselves, but also to, say, the folks at the Green Alliance. Maybe they can steer me in the right direction.

And here’s another group I can try to interrogate: SEAREI, a green energy organization right here on the Seacoast, which I heard about from my new hero, Mr. Lance Keene, who is trying to build a self-sufficient castle in New Hampshire. But more on Lance Keene in future posts.

Why am I doddering on about insulating my house and about climate change? See this post for the beginning of the Fool’s Errand.

Author: Jeff Deck

Author and administrator of this site.