There are a few ways to go about below-grade waterproofing design. First, there is positive-side waterproofing, which consists of installing a waterproofing membrane or layer between the substrate you are protecting and the source of water. This type of application is commonly referred to as exterior side waterproofing, as the waterproofing materials are applied to the outside of the building.
Positive-side waterproofing is generally seen as the least problematic option to pursue and tends to be the most successful, since it keeps water out and actually benefits from the external water pressure forcing it to work. It also allows the design team to inspect all lap joints and defects with full visibility.
The biggest drawback, however, is that once areas have been filled in with earth around the foundation, post-backfill inspection is not possible. If leaks occur due to building movement or faulty installation, repairs can only be made through excavation or interior retrofits.
There is one additional form of below-grade waterproofing to know as well: negative-side waterproofing. As you might guess from the name, negative-side waterproofing protects the surface opposite the side of applied hydrostatic pressure (e.g., the inside of a basement wall). Negative-side waterproofing keeps water from entering an occupied space and is applied to what is known as the dry face. It is primarily used for water-holding purposes (preventing water from entering a space), but it does not prevent the water from entering the substrate (wall). The main advantage of negative-side waterproofing is that it is accessible after the installation for repairs or upgrades.