[lh7777]

I wouldn't write off cork as insulation so easily -- fluffy insulation (fiberglass and cellulose) doesn't cover every scenario.

For example, Washington State's energy code now requires continuous exterior insulation. Putting a continuous layer of rigid insulation on the outside of the building reduces heat loss due to thermal bridging (conduction through the studs).

The most common material for this purpose, in the US anyway, is foam (polystyrene or polyisocyanurate). Other options are mineral wool, fiberboard, and cork. Mineral wool and fiberboard are pretty expensive compared to foam and I imagine that cork would be similar or even more expensive. But a cool thing about cork is that it can double as both insulation and cladding. I don't know if that makes it an economical choice, but someone's marketing cork for this purpose right here in Washington [1].

[1] https://www.smallplanetsupply.com/thermacork

Edit: fixed a typo