Forensic Architecture: How We Identify and Solve Problems

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View of the Lower Pontalba Building from the intersection of St Ann and Chartres Streets in Jackson Square, New Orleans.

When Knox Tumlin walked into the Preservation Resource Center office in New Orleans and proudly announced that Pascal Architects had been selected for the Re-Roofing and Structural Frame Restoration of the Historic Lower Pontalba Building, the director politely rolled her eyes and said “You are going to be seeing a lot of me then!” 

She was right. Since the Lower Pontalba building is on the National Registry of Historic Buildings, this project was going to require a lot of time in forensic research, a lot of time working with the city and state…and a lot of creative solutions. This building frames Jackson Square in the French Quarter of New Orleans and is among some of the oldest apartment buildings in the United States. As such, many of the tenants have been long standing due to its prime location and historic prominence. 

The challenge in front of our architectural team was to re-roof and repair the ridge and French framed structure of the roof to its original glory using authentic materials, not disrupting the commercial tenants on the ground floor…and of course not interfering with traffic in the highly visited Jackson Square. As if that weren’t already enough of an uphill battle, the plans for the building that were created in 1850 were the standing files on record for the building. Here’s how we did it: 

Examining The Building Envelope Using Forensic Architecture 

Similar to how a doctor runs tests before beginning surgery, a proper Forensic Architecture process ensures that our team knows exactly what they are getting into before they begin work. After looking at the original building drawings from 1850, our team began physically examining the building from every angle. Through investigative work in the attic, speaking with the roofer who provided the short-term solution 20 years prior, and digging deep in the building to locate the source of the issues with the ridge sagging, our team uncovered some issues that not only saved the client money in repairs but also showed them where modifications to the interior of the building were made over time that they were not aware of.

What was discovered was that the tenants made changes to the building specifically in attic spaces that had not only decayed the original structure of the building but also added on square footage to their apartment unit that management was not privy to prior to the investigative work. Additionally, due to the short term fix 20 years prior using 3/4” plywood overlay decking, which ignored the original water damage to the deck, ridge, and structural frame created by water intrusion, led to continued damage of all of these structural elements. This created significant problems including both rot and termite damage in all of the roof structural elements.

After thorough examination our team was able to identify all non-concealed existing conditions and save the client up to 20% on potential change orders. Additionally, our team was able to provide a record of what transpired since its original construction in 1850….many of which the state was unaware of. 

Exterior roofing during the investigative process.
Water damage and rot discovered in the attic spaces.
Ridge sagging during the investigative process.
Unstable masonry.
Chimney with unstable masonry.

Working Quickly & Working Strategically 

During the team’s first meeting with the Commercial Tenant Association, they were met with a fiery crowd. Turns out, the ground floor commercial tenants were upset about the potential use of scaffolding for a long period of time during the repair work. As a result, we had to redo the scaffolding plans to sequence them in three bay increments to help reduce the number of tenants being hampered at any one time by the construction process. 

Uncovering the 3/4” plywood overlay decking which ignored the existing water damage.
The ridge without a ridge beam for support.
Scaffolding in Jackson Square.

As for the roof work, whatever was uncovered each day had to be sealed the same day; therefore, we had to be incredibly strategic on which section we opened up and how we would complete it before each days end. 

Our team has worked in Jackson Square for over 30 years but this project presented its own unique logistic complications that took a lot of planning and strategy to keep all parties involved satisfied. 

Over the weeks of construction, we were able to salvage over 20% of antique shingles and return those to the state for emergency use on other historic properties. All new materials were approved through the Preservation Resource Center for historic compliance. Rather than change the framing, we worked to recreate the ridge and ended up fastening it from the top creating a new ridge in between fire breaks. This allowed us to work quickly and still maintain the historic material integrity of the original building frame. Drawing from our experience with Structural French Frames on the Cabildo Reconstruction Project, we were able to provide a unique, time-saving and cost effective solution for our client. 

Lower Pontalba Building project completed.

Forensic Architecture is the only reason this project was as successful and cost-efficient as it could be. While the quick fix may seem attractive to some, really examining the building envelope and gaining an understanding of the source of the issues is only achieved through Forensic Architecture. Pascal Architects has more than 30 years of experience in this process having worked with some of the most iconic historic buildings in the United States. We do this not only to save our clients time and money, but to also protect and preserve the historic infrastructure of our nation.