As apartments in Iceland are well insulated, humidity can accumulate during winter if windows are constantly kept closed. It is very important to air apartments out, keep ovens warm and wipe up water that accumulates on and by windows. If humidity or mold causes damage to apartments, resident can be held responsible and charged for repairs.
It is important that tenants do not cover windows with black plastic or similar fabric. In sunshine it can make the windows crack due to the heat. If this happens the tenant will be responsible for all cost relating to the replacement of the window.