Shared walls, parapets and where twins leak
A twin house has a neighbor on the other side of a party wall, and the roof meets that wall at a flashing line. If the neighbor's roof is higher, there may also be a step in the roofline. These junctions take a lot of water and are easy to overlook from the ground.
A good repair works out which side the water is entering from and fixes the seam, not just the visible spot. When two owners are involved, it can also help to talk early about who handles what. We explain our findings in plain terms so that you can have that conversation.

