Often our technical services team gets a call about negative side waterproofing. After further discussion, we discover the caller is really asking about blindside waterproofing, which is a positive side application. Our callers are not alone. Blindside waterproofing is a highly specialized business. It’s no surprise then that unless they work on these jobs often, even the pros have to consult other resources when determining if blindside is a negative or positive side waterproofing application.
One reliable source is ASTM D1079. Its standard terminology relating to waterproofing defines the terms like this:
Negative side waterproofing: an application wherein the waterproofing system and the source of hydrostatic pressure are on opposite sides of the structural element.
Positive side waterproofing: an application wherein the waterproofing system and the source of hydrostatic pressure are on the same side of the structural element.
Both positive and negative side applications prevent water intrusion, but each is vastly different. We've prepared a simple chart that points out the major characteristics of blindside and negative side waterproofing. Go here to download it