Challenge Your Exam Readiness With Our Free Home Inspector Practice Questions

Condensation forms when moist air contacts a surface whose temperature is at or below the air’s dew point. In cold climates, interior glass surfaces and adjacent frames often become the home’s coldest surfaces, especially with single glazing, failed seals in IGUs, or thermal bridging at frames. When indoor relative humidity (RH) is high, moisture vapor is plentiful; if the interior glass temperature drops below the dew point, condensation forms (sometimes visible as droplets or frost). Option A is the inverse of what causes condensation, while option C misattributes the moisture source to outdoor air; typical winter conditions feature dry outdoor air, and infiltration tends to lower indoor RH. UV exposure (D) can degrade materials over time but does not directly cause condensation by “raising the dew point.” From a home performance perspective, inspectors consider factors such as air sealing, insulation, window type, ventilation, and occupant behavior (showers, cooking without exhaust, humidifiers). Reporting should connect observed condensation to potential consequences—mold growth, damaged finishes, and window deterioration—and recommend actions such as controlling indoor RH, improving ventilation/spot exhaust, and addressing thermal performance (storm windows, IGU replacement, or improved insulation at framing).