Thornton Consulting were recently appointed to conduct leak investigations into a commercial building in central London. Considerable damp was in evidence in the basement at a number of locations and additional water ingress was being experienced beneath the main roof.
The building had been constructed in the 1960’s and consisted of a brick and stone façade with asphalt waterproofing to all areas. Due to the nature of the leaks, various test methods were required to accurately locate the source of each.
Typically, where the waterproofing is exposed, such as the roof in this circumstance, tests will commence with an electronic test to the membrane to locate any breaches therein. This is an accurate way of establishing the integrity of the waterproofing layer and can detect breaches that would not necessarily be visible to the naked eye. Buried waterproofing will often require a different approach, such as flood test, if conditions allow.
Buildings Leak investigations continued with a moisture profile of internal surfaces, paying particular attention to known areas of water ingress for later reference. In the basement this covered a greater area but gave a good insight into the most affected locations and provided invaluable information for corresponding areas externally and potential areas of concern. Readings were recorded for future reference or comparison with other areas of the structure.
Water tests were then targeted where necessary to positively identify the source of each leak and included localised flood testing and simulated rainfall testing both using a trace dye to confirm results when required. During and after tests leaks were monitored internally for evidence of dye or a change in moisture readings, with a comparison made to those recorded prior to tests.
At completion of investigations several different sources of the leaks were established. This included water penetrating brickwork to parapet walls which was later established as poorly installed cavity trays and breached waterproofing to the basement where pipes penetrated the structure.