Upper roof snow melted over a warm roof area
Heat loss changed the roof temperature profile.
↓House Autopsy · roof-envelope
The ice dam that sent water uphill
Meltwater backed beneath the roof covering when a frozen edge prevented drainage.
Trigger conditionsnow cover, heat loss and refreezing
Four layers, one connected story.
Water refroze at the cold eave
The growing ice ridge restricted normal drainage.
↓Ponded water moved beneath laps
The water route was opposite the normal shedding direction.
↓Snow, temperature and stain timing aligned
The durable solution addressed heat and air leakage as well as damaged roofing details.
Canonical connection
The symptom and cause are separate objects.
The autopsy preserves how evidence connected them without collapsing uncertainty into one magic answer.
Meltwater backed beneath the roof covering when a frozen edge prevented drainage.
The visible symptom was the final chapter
The investigation followed the source, transport path, affected material and verification step separately.
What changed the direction
Timing and location evidence ruled out attractive but weaker explanations before repair work began.
The durable lesson
Repair the controlling source and then verify the outcome under the conditions that previously triggered the symptom.
Source→Path→Damage→Verify
