Every home must handle three very different forms of moisture:

- Liquid water (rain and leaks): The most visible, controlled by cladding, flashings, and drainage layers.

- Air: Less visible, but a powerful carrier of moisture. Airtightness and deliberate ventilation keep it under control.

- Vapour: The smallest particles, constantly moving through materials. Whether vapour can safely escape depends on material properties like µ-value and sd-value.

When we understand these layers, we can design walls and roofs that both protect and breathe.