Water seldom stays above the stain. It runs along joists, drops through light fixtures and soaks into insulation, so the visible mark on the ceiling is usually the smallest part of the problem.
Tracing where it started
A ceiling leak almost always begins with a plumbing fixture, a supply pipe, a drain or the roof above. The crew works backward from the stain with a moisture meter and a thermal camera, checking the bathroom, kitchen or attic that sits over it before any drywall is removed.
- A tub, shower or toilet seal on the floor above
- A pinhole in a supply pipe or a loose fitting
- A failed roof section or flashing
Opening the ceiling the right way
Small access holes show whether the bay is wet. If it is, the wet drywall comes down in clean sections and the insulation above it is removed, since both hold moisture against the joists. Drywall that tests dry is left in place, which keeps the repair smaller and cheaper.
Drying above and below
Dehumidifiers and air movers dry the joists and subfloor from the opened ceiling, and the floor under the drip is checked for wet padding. Leaks that begin at the roof edge are covered under ice dam damage, and a supply break is handled as a burst pipe.
Padding under a soaked ceiling hides water too, so carpet in the room below is checked at the edges and lifted where the meter reads wet.