/diy/ - Do It Yourself

Not an expert on this topic, but here in Europe (in my country at least) most houses are brick houses.

The way they're done is like in this pic. An inner wall, insulation, cavity, outer wall. I think it's called "Cavity wall" in English.
They're hold together with these steel pins, they have a little nudge in them in them where the water can collect and fall off.