I’m sure this woman was quite comfortable. But that’s my point. This isn’t the way an American or Canadian is used to dressing at home in the winter.

This is idential to the way we did pitched roofs. Except there, we work with 2×6 or 2×8’s… (was long ago). Flat or pitched, both are ventilated.

Here, we’re dealing with a concrete roof. We have to strip off everything to bare concrete, then put in styrofoam to get the R value you want. You dont want the whole roof flat styrofoam, so you build parapet walls in sections on the roof and place the styrofoam up to about 2cm from the top. Then you cover the whole thing with membrane.. silver on the topside, tar on the downside. You can paint that over with waterproof, UV resistant paint or put on patio stones. That’s how you would insulate a flat roof here.
In my case, we have 3 flat roofs, and 2 terraces that sit atop rooms. The roofs were all recently membraned, so we needed to rip out those 2 roofs, adding costs that weren’t required.
The terraces were already screwed and we had to strip them down anyway. To raise that floor 4 to 7 cm to lay in the styrofoam would have meant raising the doors, which either means shortening their height, (for pygmies) or smashing out the top of the door and raising it up. That means rebuilding the 80 year old door frames and getting a masonry artist to rebuild the porticos and carve or mould plaster headers.

The house is not a perfect rectangle. There are walls that jut in and out. To insulate those, would mean strapping all the walls… using drywall(sheetrock). Sheetrock is expensive in Uruguay… Trades that work with it aren’t very good with seams. I dont know what cost it would add, but it would be a lot. But that isn’t the real problem. When you renovate an old stately house, you have old stately wood windows that were built by craftman. You have to move them around to fit the new thicker wall. Or they’ll be sunk into the wall. Not terribly pleasing to the eye.

Speaking of the windows and doors, there’s your biggest single source of heat loss. Old, stately, beautiful windows are loose fitting. Glass is not thermalpane. Most of my house is french windows.. small squares… beveled on top of that. An important reason for buying this house was the woodwork and those windows. The only thing I could do was put up insulated cortinas (rollups).

If I had to take a wild guess, it would have added at least USD$30K to USD$40K to do the ceilings and walls. Let’s say you could reproduce those windows, another USD$15K.

To build a house from scratch, is another story altogether. Then any architect could give you a price difference, probably no more than USD$20K=USD$30K extra for a 300m house.

My wife is from Wisconsin and says to this day that she was never so cold in her life as when she lived in southern Brazil. There, most people use electric spot-heaters. And as you correctly pointed out, they are horribly uncomfortable.

We can still remember waking up and being able to sometimes see our own breath while still in bed. In order to take a shower, you had to undress in the bathroom which was often around 6 C (40 F). Enough to make a man out of you.

As an engineer, I agree with your assessment of the heating issues and the pro and cons of the main alternatives.

For us, I think we will stick to central losa. One more plus for apartments versus houses. Winters feel very long if you have to dress like an astronaut inside your own home.