California Residential Inspector Practice Exam

Is it correct that a vapor retarder is required between the concrete floor slab and the base course of a garage structure?

1. Correct

2. Incorrect

3. Only in cold areas

4. Only if specified by the engineer

The correct answer is: Incorrect

The requirement for a vapor retarder in garage structures, particularly between the concrete floor slab and the base course, is typically dictated by local codes and environmental conditions rather than being universally mandated. In most cases, a vapor retarder is not required in residential garage applications because garages are mostly open to air, which reduces the risk of moisture accumulation. Additionally, the concrete slab is often designed to be placed on a compacted base that allows drainage and ventilation, helping to mitigate moisture issues. In many building codes, the requirement for vapor retarders is more applicable to living spaces or finished basements where moisture could become a more significant concern. Therefore, indicating that a vapor retarder is required in all situations, including garages, is incorrect, making it clear why this option is appropriate. Understanding the specific site conditions, climate, and intended usage of the space is essential to determine the necessity of a vapor retarder in construction practices.