Yes. Our slate from Oppdal, Otta and Offerdal is all 100% frost-proof and therefore very suitable for use in a tough Nordic climate.  The porosity of a material is calculated by measuring the maximum amount of water that it attracts. In general, porous materials with high water uptake are the least strong and durable. All of our slates have water uptake far below what the European standard states as a limit for frost protection (NS-EN 12326-1: water absorption ≤ 0.6). See more in our product datasheets here