Finding hundreds of hidden breaches before the courtyard was buried
Case study: Electronic leak detection (ELD)
Two podium courtyards over occupied space were about to be covered with pavers, soil and amenities. Once that happens, every pinhole in the waterproofing becomes a leak into the units below.
At a glance
- Building: New multifamily community with two podium courtyards
- Location: Charlotte, North Carolina
- Services: High-voltage electronic leak detection, three rounds
- Standards: ASTM D7877, with ASTM D8231 and E2128 for reference
- Result: Every breach marked, repaired and re-tested before the membrane was covered
The problem
A hot rubberized asphalt waterproofing membrane had been installed over the courtyard decks. While it sat exposed, other trades were working overhead installing cladding, and the decks were used for staging and foot traffic. Visual inspection cannot find pinholes or punctures in a dark membrane, and a single missed breach can spread water across a large area of the structure below.
What we did
We met the waterproofing contractor on site and scanned both courtyards with high-voltage ELD, sweeping a charged broom electrode across the membrane. Wherever the membrane is broken, current finds a path to the grounded deck and the equipment signals. Each breach was marked on the membrane with a red crayon and photographed. High voltage was used at the contractor's request because the membrane was dry and exposed.
Because trades kept working on and above the decks, we came back for two more rounds. Each round re-tested the repaired spots and the rest of the membrane.
What we found
The first round found well over a hundred breaches, most of them consistent with foot traffic, dropped materials and cladding work overhead. Debris and staged materials kept parts of the decks from being tested, so we recommended another round once they were cleared. The later rounds confirmed that earlier repairs held, and they also caught new damage from ongoing construction. That is exactly why re-testing right before cover matters.
What we recommended
Repair every marked breach to the manufacturer's guidance, keep traffic and staging off the membrane, and re-test no sooner than 24 hours after repairs and right before the protection and overburden go down.
Why it matters
A breach found during construction costs a few minutes and a patch. The same breach found after pavers, soil and amenities are installed means tearing out finished work over occupied units. ELD is the only practical way to know the membrane is whole before it disappears.
Client and property names are kept confidential. References are available on request.
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