We discovered that Ice and water shield was installed under all the slates but whomever
had attempted this repair neglected to get up high enough to the critical area where the house meets the addendum roof. By removing the flashing and inner plywood sheathing we exposed the holes in the tarpaper shield and then we were able to add in the heavy water barrier behind the copper flashing and inte-
grate it into the ice and water shield under the slates. We then added in slate and put our own ice and water shield over top of that.