Exterior Waterproofing Is A Very Effective Way Of Preventing A Basement Leak Exterior waterproofing is a more comprehensive, multi-step job, involving major excavation work, installing protective coating and a drainage membrane, as well as a new weeping tile system, but it’s a highly effective way of keeping your basement dry. Exterior waterproofing is most definitely not a job that should be left to amateurs or weekend warriors. Overall, a basement waterproofing system will funnel water away from your basement. The damage caused by a basement leak, leading to water damage to dry wall, wiring, floors, mould and mildew issues, can run the homeowner into the thousands of dollars. There is also the incalculable emotional cost that comes with seeing family possessions and heirlooms permanently destroyed.