Core TradesQuestion 118 of 700
In a mixed California climate, a vapor retarder placed on the WRONG side of the insulation can cause:
a.Higher R-value
b.Better air sealing
c.No possible harm
d.Trapped moisture and condensation within the wall, leading to rot or mold
Explanation
A vapor retarder on the wrong side can trap moisture that condenses inside the assembly, causing rot, mold, and reduced insulation performance. It does not raise R-value, improve air sealing, or be automatically harmless; placement must follow the climate-appropriate design.
Law Reference: 2025 CA Energy Code (Title 24, Part 6)Practice all 700 questions free — no signup required.
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