The drip edge of a slate roof often needs to be repaired because a Toronto roofer is looking for a quick and cheap way to attach gutters to a house simply nail them through the slate using strap hangers. This damages the slates, which eventually have to be repaired or replaced.
It’s important not to allow strap hangers to be used on slate roofs unless the hangers are fastened underneath the slate. Originally, many slate roofs did use strap hangers nailed to the sheathing under the slate because the fascia boards on the older houses were not plumb (straight up and down), making it difficult if not impossible to fasten the gutters to the fascia. When the old gutters wore out and the old strap hangers rusted away, the contractors solution was to nail new strap hangers on top of the roof right through the slate, thereby damaging the roof.