Historically, architects and other designers have often called for a flood test to be carried out on horizontal waterproofing systems when the membrane is under a green roof, wear-course or topping slab where direct inspection of the roof membrane is difficult or impossible. ASTM D5957, the Standard Guide for Flood Testing Horizontal Waterproofing Installations, is typically referenced for the test. Flood testing takes from 24 to 48 hours, is often inconclusive and can cause structural damage. As a result, NRCA and CRCA do not recommend conducting flood tests as part of a routine quality-control or quality-assurance program for new roof systems
The first low voltage electronic leak detection (ELD) testing method for waterproof membranes was developed in Europe in the early 80s. Several new ELD methods have been developed since, and they fall in to two main categories: low voltage (48 volts or less) and high voltage (600 volts or more). Although ELD testing has been in use for several decades, no standard describing the methods and limitations had been developed to guide the industry. As a result, there was confusion, misunderstandings and misconceptions surrounding ELD.