North Carolina Building Contractor License Practice Exam

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What does efflorescence indicate about masonry units?

Excessive outdoor exposure
High moisture content
Improper installation
Use of low-quality materials

The correct answer is: High moisture content

Efflorescence is a crystalline deposit of salts that can often be observed on the surface of masonry units. Its presence indicates a high moisture content within the masonry. When water penetrates through the mortar or the masonry material, it can dissolve soluble salts contained in the masonry or in the groundwater. As the water evaporates, it leaves these salts behind, forming the visible white powdery deposit known as efflorescence. This phenomenon suggests that there are issues with moisture management within the masonry structure. It may stem from inadequate waterproofing, high humidity levels, or other factors that cause excess water to interact with the masonry. Identifying efflorescence is crucial as it serves as an indicator of underlying moisture problems, which could lead to more significant structural issues if not addressed promptly. Understanding this can help contractors take corrective actions to mitigate moisture problems and improve the longevity and performance of masonry work.