I have over one meter of insulation in my attic. But realize that way this home was constructed, a good portion of the roofline is directly against the ceiling.

I have over one meter of insulation in my attic. But realize that way this home was constructed, a good portion of the roofline is directly against the ceiling. You can't add insulation to that area. It is very poorly insulated by design. The snow on my roof always melts in this area and make some nice ice dams as it runs off. There is no fixing that without a major change to the home. The only thing that could freeze when I shut off my water main is the water main in the street. If that freezes, that isn't my problem. Nor is it anything I can do something about.