01
Look beyond the roof surface
Water observed near the junction may involve roofing, flashing, masonry, or coping. Ask the assessment to distinguish these possibilities and identify inaccessible areas. A repair limited to exposed slate will not answer a problem arising elsewhere in the wall assembly.
02
Coordinate the responsible trades
Have the project team define which trade opens the junction, which repairs the wall components, and which reinstates the roof connection. Record how the new work joins retained materials. If the wall is historic, document existing visible features before alteration. A complete scope follows the possible water paths instead of dividing the problem solely according to trade boundaries.