Electronic Integrity Testing of Hot Melt Waterproofing, East London

Project Overview

Thornton Consulting was appointed to carry out electronic integrity testing to a hot melt waterproofing system on an apartment block under construction in east London. The testing formed part of the project’s quality assurance process, providing an independent check that the waterproofing was watertight before the next stages of the roof build-up were completed.

The development included flat roof areas where a hot melt waterproofing membrane had been applied by the roofing contractor. As with many residential construction projects, the programme required follow-on trades to install insulation, protection layers and paving shortly after the waterproofing works were completed. This made early verification essential. Once these layers are installed, access to the membrane becomes limited and any future investigation or repair can become more disruptive and costly.

Our Role

Thornton Consulting undertook electronic leak detection of the completed waterproofing areas to identify any defects, breaches or vulnerable points before they were covered. The aim was not only to confirm the integrity of the system, but also to support the wider project team by giving confidence that the roof areas could progress to the next stage of construction.

The testing was carefully coordinated with the roofing contractor to suit the site programme. Areas needed to be prepared and made available in sequence, with the membrane sufficiently complete and accessible for testing. Close communication was required so that testing could be carried out before insulation and paving works advanced across the roof. This helped avoid delays while ensuring that the waterproofing was properly checked at the right point in the build.

Findings

During the electronic leak detection, a small number of breaches were indicated within the waterproofing system. These locations were marked clearly on site and reported to the project team. The roofing contractor was then able to repair the affected areas promptly. Following the repairs, the relevant locations were retested to confirm that the breaches had been successfully resolved.

This process provided a practical and efficient QA checkpoint. Rather than waiting for leaks to appear after completion, the project team was able to deal with defects during construction, while access was still straightforward and the roofing contractor remained on site. This reduced the risk of water ingress, protected the building fabric and helped maintain confidence in the waterproofing installation.

The Benefits

Electronic testing is particularly valuable on hot melt waterproofing projects because it can identify breaches that may not be visible during a standard visual inspection. In this circumstance, the breaches were attributable to site damage, confirming the importance of independent integrity testing of newly installed waterproofing systems. By using electronic leak detection methods, the waterproofing could be assessed thoroughly before it was concealed beneath insulation, ballast, decking or paving.

Outcome

The east London project demonstrated the benefit of integrating waterproofing integrity testing into the construction programme. Through coordination with the roofing contractor, defects were identified, repaired and verified before the roof build-up continued. This gave the client and project team added assurance that the apartment block’s waterproofing had been tested and confirmed as watertight before being covered.

The result was a clear, documented quality assurance process that supported the successful progression of the roofing works and helped reduce the risk of future waterproofing issues.

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