A copper supply line under a kitchen subfloor ruptured at 2 AM during a multi-day freeze. Water was moving toward original hardwood flooring and the homeowner could not locate the main shutoff in the dark.
We talked them to the shutoff by phone while en route, arrived in 40 minutes, isolated the branch, and replaced the split copper section. The hardwood was saved because the supply was closed within minutes rather than hours.
We insulated the remaining run under that subfloor and sealed two open crawl space vents. That kitchen has been through three winters since without incident.