NASCLA Accredited Commercial General ContractorThermal and Moisture ProtectionMedium
A commercial building's foundation walls are being prepared for backfilling. The specifications call for dampproofing application. What is the primary function of applying dampproofing to a foundation wall?
- ATo provide a structural bond between the foundation and the backfill.
- BTo prevent the passage of liquid water under hydrostatic pressure.
- CTo create a vapor barrier to stop moisture migration from the soil.
- DTo resist the absorption of incidental moisture from the surrounding soil.
Show answer & explanationAnswer & explanation
Correct answer: D. To resist the absorption of incidental moisture from the surrounding soil.
Dampproofing is designed to resist the absorption of incidental moisture from the soil, preventing dampness from wicking into the foundation wall. It is not intended to withstand hydrostatic pressure, which requires full waterproofing.
Why the other options are wrong
- A. Dampproofing materials do not provide structural bonding; their purpose is moisture resistance.
- B. This describes waterproofing, which is a higher level of protection than dampproofing and designed for hydrostatic pressure.
- C. While dampproofing offers some vapor resistance, its primary function is liquid moisture absorption, not specifically vapor diffusion.
Dampproofing Function
The application of a material to a foundation wall to resist the absorption and capillary action of incidental moisture from the soil, preventing dampness within the structure.
- Resists non-hydrostatic moisture
- Commonly asphalt-based coatings
- Less robust than waterproofing
- Prevents soil moisture from wicking into concrete/masonry
Memory trick: Dampproofing: 'Damp' means 'Diffuse' moisture, not full 'Drowning'.