The apartment conversion from one-bedroom to two-bedroom apartment in a historic building from1842 is small in scope of work in terms of changes to existing layout, however the execution required technical expertise and understanding of flat arc slab terracotta building system. Our team worked closely with a structural engineer, special inspection agency and HILTI team to find design solutions for partitions’ framing and fire-stop systems.
The challenge was to select fastening system that would be adequate for historic hollow terracotta block substate at the head of wall. We tested HILTI epoxy 200 HY and 270 HY anchors with sleeves, but those did not perform well. Python MT Screws designed by a Python Fasteners, specialty research and fabrication firm led by their in-house engineering team were a satisfactory solution; we used MT 13.5” long screws. Amaracon special inspection agency tested post installed anchors on 250lb pull force and certified for project’s closing paperwork.
Concealed conditions such as large opening in structural slab were a surprise at post-demo stage. The opening was a bridge in a fire-resistance rated floor/ceiling assembly which were restored with HILTI fire-block product. For this project nine custom designed HILTI Engineering Judgment based design solutions were generated related to fire-stopping scope of work. Our office performed NYC DOB fire-resistant penetrations and joints special inspection.
This small but complex project is a testament to how a delicate design approach is required for historic buildings in New York City.