Because the layered structural system concealed a cavity—believed to be the coal-cinder layer—many theories about the source of the leaking water were put forward by the design team, construction team and owner’s representatives. The three most likely source theories were:
- Water trapped before the membrane replacement in the coal-cinder layer of the structural system continued to leak through minute seams in the steel structure between plates and around 100-yearold rivets.
- Despite meticulous flood testing of the new waterproofing system, somehow a deficiency in the system was allowing new leaks.
- Original portions of rainwater conduits from the platform and track drains that were embedded in the structural floor system were not able to be replaced and were presumed to be leaking into the structural cavity formed by the coal-cinder fill. The porous nature of the fill allowed rainwater to eventually leak through the structural system.
Despite months of leak testing with dyed water for failures in the rainwater conduits, a last-ditch repeat effort to retest the new membrane by flooding it with dyed water revealed the track drains were experiencing a failure at the interface with the new waterproofing membrane. This method finally exposed theory No. 2 as the cause of the symptom. This was a far more manageable problem than scenarios 1 and 3. The drains were resealed, and the problem was solved. The efficiency of the process, however, may have been optimized if an integrated design process could have been utilized.
Project Delivery
Because more problems are ultimately solved by preliminary testing and analysis of an existing building, most design budgets do not include the costs of such investigations. The ease of incorporating such procedures in the pre-design phase of a project often relies on the project
delivery methodology being used. Delivery methods that allow a construction entity, such as construction management and design/build, to be involved during the design phase work best because the professionals who are best suited to remove portions of a building for direct inspection or testing of existing building components are available to the architect before or during critical design phases.
Delivery methods, such as the traditional design-bid-build or negotiated bids, are more problematic in this regard because the architect must find appropriate consultants to perform testing and investigations before the final construction entity is selected. In many instances, funding of such efforts is difficult and retaining the appropriate consultants places a liability for discovery of all concealed problems on the shoulders of the design team.
Although all renovation and restoration projects have significant differences physically and process-wise, it is safe to conclude that more investigation of hidden and concealed conditions will result in fewer surprises that create change-orders during the construction process. How these investigations are achieved varies significantly with the project delivery method chosen. If a construction professional can be brought into the project team early in the design process, every part of the team—owners, architects, consulting engineers and the construction entity—will be better off.