Failed underlayment under tile that still looks good
Why it happens here
The underlayment on Avenel's older tile roofs has been baking and freezing for decades. It dries out, cracks and stops shedding water, but the tile above it hides the problem until water shows up inside the house.
Our approach
We trace the leak to its real source with a moisture meter and infrared detector, then lift the tile and inspect the underlayment directly. If it has failed across a slope, we replace it and relay the tile rather than patching around it.