What is positive vs negative side waterproofing?

Positive side waterproofing is applied to the side of the structure in direct contact with the water source (e.g., the outside of a basement wall before backfilling). The water pressure pushes the membrane *onto* the structure. Negative side waterproofing is applied to the interior side (away from the water source). The water pressure pushes the waterproofing *away* from the substrate. Negative side systems rely entirely on bond strength, making surface preparation critical.