Diagnostic Guide
Why Is My AC Ductwork Sweating in the Attic?
Attic AC ducts sweat when humid air reaches a surface below its dew point. Learn how insulation, duct leakage, and other water sources fit in.
MoistureLeakingDiscoloration
Home system
Attic & Insulation problem guides
Heat, moisture, ventilation, insulation, and attic warning signs. Start with a symptom or use the Problem Finder when you are not sure which guide fits.
Use the Problem FinderBrowse attic & insulation symptoms
Published guides
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Diagnostic Guide
Why Is My Air Handler Sweating?
An air handler can sweat when humid air reaches a cold cabinet surface. Learn how to distinguish condensation from drainage, thawing ice, and other leaks.
MoistureLeakingDiscoloration
Diagnostic Guide
Why Is My Ceiling Getting Moldy?
Mold-like spots on a ceiling point to recurring moisture. Use location, timing, and moisture clues to distinguish condensation, leaks, attic, plumbing, and HVAC sources.
MoistureDiscoloration
Diagnostic Guide
Why Is There a Water Stain on My Ceiling?
A ceiling water stain shows that moisture reached the material, but not whether it is active or where it began. Use location, timing, and what is above it to narrow the source safely.
MoistureDiscolorationLeaking
Diagnostic Guide
Why Is There Mold in My Attic?
Mold-like growth in an attic points to a moisture problem, but not one specific cause. Use location, wetness, rain timing, season, and nearby systems to narrow the source.
MoistureDiscoloration
Diagnostic Guide
Why Is My Ceiling Wet After It Rains?
A ceiling that repeatedly gets wet after rain makes exterior water entry more plausible, but the wet spot may be far from where rain entered. Use timing, location, and attic clues to narrow the source safely.
MoistureLeakingDiscoloration