Burst pipes in attached homes
In a condominium or apartment, a burst on an upper floor sends water through the ceiling below and into a neighbor's unit. Both units are mapped, and the records are kept separately so each owner or tenant has what the insurer needs. See condo and townhome water damage for that process.
A burst inside a wall cavity may not be seen at all until the paint bubbles, so mapping looks beyond the visible wet spot.
