A roof of a dwelling shall be maintained in a water-tight condition so as to prevent leakage into the building. Without restricting the generality of this section, the maintenance includes repairing of the roof and flashing, applying waterproof coatings, installing or repairing eave troughs and rainwater piping and using other suitable means. Dangerous accumulations of snow or ice or both shall be removed from the roof of a dwelling or an accessory building.