ICC Commercial Building Inspector Practice Test

When must waterproofing be installed on below-grade walls?

1. At the base

2. When the wall is completed

3. From excavation

4. Before masonry is laid

The correct answer is: At the base

Waterproofing must be installed at the base of below-grade walls as this is where the wall is most vulnerable to water infiltration. The base is in direct contact with the soil, which can retain moisture and exert hydrostatic pressure against the wall. Proper installation of waterproofing at this level helps to prevent water from entering the structure, protecting it from potential damage caused by moisture, mold growth, and structural issues associated with water intrusion. The other options do not address the critical area for waterproofing effectively. Installing it when the wall is completed or before masonry is laid may not provide sufficient protection against the lateral water pressure that builds up at the base. Moreover, starting the waterproofing from excavation does not pinpoint the specific location where the most significant challenge occurs regarding water infiltration. Thus, focusing on the base is crucial for ensuring effective waterproofing in below-grade wall construction.