At the moment, Britain and Ireland are both experiencing the second bout of severe weather conditions in ten months, with temperatures some nights down to -19C. If you have a flat roof, you could be running the risk of water damage as and when the thaw comes. What you need is a Dambuster Deicer, available right now from the manufacturer, in Sicklerville, New Jersey, USA, or usual stockists. A good Christmas present for that uncle who likes DIY?
Dambusters Blog 