Question
What is positive vs negative side waterproofing?
Expert Answer
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.
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