Scope Creep

by Mona Abdelfatah on February 14, 2017

I recently attended an informative presentation, by Shiroy Ranji of STV, on scope creep and how to avoid it during a SEAoNY seminar. There are a number of ways that a project’s scope of work can expand unexpectedly during construction. One category is particularly difficult to avoid when dealing with older buildings: unforeseen conditions. Underlying structural problems can only be identified if they result in visible damage to interior or exterior finishes. And it is not practical to conduct an invasive survey of the entire existing building structure for every project. However, when we uncover compromised structural elements, we have a responsibility to our clients and to the general public to address any unsafe conditions, even if they are not directly related to the original scope of work.

The American Tract Society Building on Nassau Street was a good example of scope creep due to unforeseen conditions. The original scope, which we have discussed a few times in the past, was to replace the decorative terracotta angels at the four corners of the penthouse and design structural supports that can carry the weight of the angels and keep them tied to the building. We ran into our first problem with the brick back-up behind the angels. Given the amount of separation between the angels and the building, we anticipated some masonry repair and replacement. Once the angels were removed, however, we discovered that ALL of the corner masonry was damaged and that large cracks (wider than one inch in some areas) had developed within the masonry wall beyond the angels’ wings. While the masonry was not contributing to the structural integrity of the building itself, the supports for the angels would rely on the masonry for bearing and anchoring. Therefore, we decided to replace most of the masonry behind the angels, infill the crack in the wall beyond with gravity fed grout, and install brick ties to the existing masonry and steel columns for lateral stability.

As the masonry was being removed, we discovered a second issue. The steel columns at the corners were heavily rusted and deteriorated down to the base of the angels, suggesting that the observed damage was due to water infiltration from the dislocated angels. Fortunately, the steel deterioration did not extend below the base of the angels. It was necessary to repair the columns where we observed damage because they are part of the building structure, and we intended to tie the newly replaced masonry to the columns for added stability. The level of deterioration and access to the columns varied from corner to corner. As a result, we had to specify a unique repair for each column.

We found a third problem when we exposed the base of the second column for cleaning and repairs. The steel double channel lintels above an opening adjacent to the base of the angel were heavily rusted. We asked the contractor to expose more of the channels to determine the extent of deterioration and found sound material two feet from the end. The lintels were beyond our intended scope of work. Nevertheless, we recommended repairing the steel as part of the project because it was necessary for building safety and the lintels would not be accessible once the new terracotta was installed.

When we reached the base of the last column, we slowly uncovered yet another problematic condition: an entire span of a wind-bracing truss hidden within the wall had completely deteriorated. First, the contractor exposed a rusted and warped plate connection to the steel column where the steel was being cleaned and repaired in preparation for terracotta installation. Additional probes revealed that there was a truss connected to the plate, and we noted significant material loss along the top and bottom chords of the truss all the way to the next column, about 15 feet away. Once the truss was fully exposed, we found that the diagonal braces were also compromised. Though the truss was not related to our work, it was an integral part of the structural system for the building and had to be repaired. We designed a narrow truss that would replace the capacity of the lost steel sections and could be installed while the existing truss remained in place.

Of course, it was frustrating to be the constant bearers of bad news. Clients are never happy to hear about unexpected delays and increases in project costs. We explained that the steel columns were concealed in the walls behind the angels and could not be examined until the decorative elements and the masonry were removed. And, since our investigation of the building structure was limited to the area supporting the angel, we did not even know that the truss existed, let alone that it was severely compromised. In the end, we were fortunate to have a client who understood that the scope creep due to the unforeseen, yet necessary, repairs was not avoidable.

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