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We have recently completed our building leak investigations service for a client in west London who was experiencing leaks in a residential block.

The building was approximately 5 years old with leaks evident into to three rooms at lower ground level. The area above was a small terrace consisting of a concrete deck, insulation, single ply waterproofing and paving finishes. The void beneath the paving was occupied by pipework and, as such, was quite congested.

The initial phase of the building leak investigations was to conduct a flood test to establish the integrity of the waterproofing, this included a trace dye incorporated in the water. A trace dye can aid with accuracy of results, when used in a methodical manner, as it indicates which item tested is contributing to the leak when there are potentially numerous causes.  It can also be useful when a leak can take some time to manifest internally, such as through thick concrete slabs.

When positive results are achieved from the flood test, the next stage of the process can be undertaken. The process of undertaking a flood test first to buried waterproofing can applied to a number of different buried systems, including green roofs, paved terraces etc, and can save time and money by ensuring subsequent testing is targeted to the correct areas.  In this case, since dyed water emanated at the leaks site, we were able to proceed with removal of paving to expose the waterproofing beneath.

Electronic leak detection was then undertaken to the exposed waterproofing where a number of significant breaches were identified. There are two main test methods for electronic leak detection, both of which can accurately locate breaches in the waterproofing.

Both test methods rely on the same basic principle to function, whereby the waterproofing membrane is an electrical insulator and the deck or substrate beneath is electrically conductive.

  • Wet test method (low voltage). A low voltage pulse is emitted from a conductor loop around the perimeter of the test area which is conducted across the wet surface of the membrane. If a breach is present this is located by two probes attached to a detector unit which locates the exact point at which the signal is earthed to the underlying substrate.
  • Holiday (pinhole) method – This is a high voltage test method which requires the surface of the membrane to be dry. The test machine passes a high voltage through a phosphor bronze brush which is swept across the surface of the membrane. Where a breach is present, a voltage drop occurs in the machine which is indicated by a beep from the unit. Again, this is a very accurate test and can exactly pin-point a breach.

If you would like further information of our building leak investigations service, flood testing or electronic leak detection of waterproofing membranes, please contact our office on 01342 410508, or use the Contact Form