Just curious. I would think that fiberglass insulation is a fairly modern idea. What did people use before it was invented?
Horsehair
Don’t forget shredded, ground up paper.
A friend of mine was helping a friend of his with an outbuilding c.1920s. The walls were insulated with old newspapers and magazines that were just nailed in.
I keep hearing Dean on Hometime talk about something called “rock wool,” but I haven’t ever bothered to learn what it is. It sounds suspiciously like asbestos to me, but I’m sure they’d say if it were.
How about “nothing”?
My house was built in the 1920’s and originally had no insulation in the walls, just air. Later some kind of stuffing like cotton was added. It looked like a fire hazard.
Rockwool is glass fibre insulation.
Papers, as mentioned were very common as was sawdust.
Oh yeah, other wood “shavings” were quite common too.
Rockwool is molten furnace slage (or certain rocks) subjected to steam.
http://www.gelpeyinsulation.com/history.htm
It seems to be more ‘fireproof’ than ‘keep the heat in’. Going the other way, I think an older dorm at my college was insulated with coal.
-lv
You’ve got to realise that people had different expectations of comfort and warmth in “the olden days.”
Houses built from logs get a lot of natural insulation from the thickness of the logs themselves, but the occupants were definately not “toasty.” Bedrooms often weren’t heated at all. Sometimes, the only room of the house which was heated was the kitchen. (Fires require a lot of work to maintain, not to mention the firewood itself.) It wasn’t uncommon in the 1800’s to wake up and find the water in your wash-basin frozen solid. People slept under mounds of covers, and usually at least two people shared the bed, which kept them warm. Sometimes, people would put a brick in the fire and once it was heated, wrap it in cloth, and take it to bed with them. They would dress in front of the kitchen fireplace in the morning.
Fireplaces are also innefecient, not throwing very much heat out into the room. Most of it goes up the chimney. It wasn’t until the Franklin stove became common that even the kitchen was truly warm.
People wore much more clothing in earlier times, which helped keep them warm in the winter, but was probably hell in the summer. A woman typically wore about five layers, including corset, petticoats and chemise, stockings, and bloomers. In the Victorian era, women always wore shoes in the house.
Wealthier families, who built their homes from brick, had it a bit better. Brick walls are thick, and help hold in heat. They could also have fireplaces in the bedroom, because they had servants to tend to them, and could afford the fuel.
So as Mangetout implied, Rock wool was a precursor of modern fibreglass. Where I’ve seen it, it came as a loose filling material, rather than in bats or sheets. It’s Horrible stuff to clean up.
Is Rock wool that stuff that makes little bitty cuts all over your body that itch like the dickens? I remember playing in the big box the insulation came in and suffering from it.
(Of course, I should have known better at forty.) 
I didn’t mean to imply that rock wool couldn’t be made out of melted glass, I just wanted to point out that you can make it with any melted rock-like substance.
-lv
Brick has good heat capacity, but very poor thermal insulation properties. The brick house where I grew up was built just after the Civil War. The space between the exterior brick wall and the interior plaster walls was insulated with a layer of vermiculite, which is a light and puffy mineral. Perlite is another light and puffy mineral that would probably work about as well.
Asbestos was widely used as cavity insulation in the 50s and 60s. In times of glut production, Australian houses have been insulated with wool.
Cavity brick construction provided very good insulation by itself, as does rammed earth construction and mud brick.
Regards,
Agback
The only not mentioned material which is in common use (still is, on certain environmental projects) is compressed sheep wool.
Quite common in old vernacular buildings in Ireland, and elsewhere.
I’m not a carpenter, so I expect I got some of the measurements and terms wrong.
When we were doing some remodeling in my childhood home, which was built in 1820-something, we found that it was largely un-insulated. The internal walls were wood slats, about 2" high, maybe 1/4" thick, and about 2’ long nailed to the studs. There were gaps of about 1/16" between each. Then the whole thing was just plastered over with a combination of plaster mixed with horsehair. Sometime in the 1960s, somebody put that pressboard wood paneling up over the top of the plaster wall.
Inside the wall, we found a mix of junk. Old rags, newspapers…even 10 of the old tin printing plates for the local newspaper from the 1880s. We kids played with them to make ‘thunder’ noises until my sister almost cut her finger off on one of them.
The newspaper was in single sheets, wadded up - like you would use to pad a package with.
Horsehair, as mentioned, was also common. Our house, turn of the century-ish (a bit before, but it is unimportant), was insulated with horsehair, which is one of the most annoying materials I’ve come across. That house was a huge headache… NEVER take drywall, standardized measurements, and fiberglass for granted.
I live in an old house in a cold, snowy area. The bulk of our house has been redone and insulation has been added, but there’s a few areas where you can see the original insulation - newspapers. Finnish newspapers, to be exact. Lots and lots of Finnish newspapers. Maybe the Finnish words are warmer than English.
Lissa wrote:
On a side note - if a house is even moderately insulated (ie, no big cracks for the wind to come whipping through), a wood stove (as opposed to a fireplace) will be VERY effective heat. From living in various spots around the country, I know even now that the level of insulation and “tightness” of a house is vastly different in places where it doesn’t get particularly cold in the winter vs. where it does get cold. They just build houses tighter up here in da North. I’m willing to go out on a limb and guess that this practice was the same 150 years ago. Given that, I’d be willing to bet that the Finns living up here next to Lake Superior in 1850 were heating their Finnish-paper insulated homes with wood stoves and were snug as bugs. One fairly small woodstove can be hot as hell in a small to medium size house.
(anecdotal evidence: When growing up, a friend of mine’s father heated their house in the winter with a wood stove. It was a fairly decent sized house, maybe 2000 square feet. The family kept their front door and windows open pretty much all the time, because their house was too damn hot throughout most of the winter. We tend to do the same thing in our cabin in the woods - the stove keeps it so hot that the door has to be kept open a lot.)