> How does that work exactly? Here's how I understand it: I would have to cover an entire building with some sort of a skeleton (layer) of wood, with an air gap

> How does that work exactly? Here's how I understand it: I would have to cover an entire building with some sort of a skeleton (layer) of wood, with an air gap in between. And it will cause the rain drops to slide down to the ground instead of the wall absorbing it. You have external cladding to protect against bulk water, UV; it is generally metal siding, brick, stucco. You then have a >5mm air gap between that cladding and the next layer of your building: * https://www.buildingscience.com/documents/insights/bsi-001-the-perfect-wall https://www.buildingscience.com/documents/insights/bsi-001-t... This is because moisture will either get through the cladding, or the cladding itself will absorb water (brick, stucco), and needs a way to dry. You don't need a lot of space behind the clapping, but you need something: * https://en.wikipedia.org/wiki/Rainscreen https://en.wikipedia.org/wiki/Rainscreen * https://www.dupont.com/products/tyvek-drainvent-rainscreen.html https://www.dupont.com/products/tyvek-drainvent-rainscreen.h...