765 Riverside Drive

765 Riverside Drive is a residential building in Washington Heights that needed to install new mechanical equipment on its roof as part of a building-wide HVAC system upgrade. The existing roof structure had been designed for its original loads and was not rated to support the weight and vibration of the proposed equipment, which included multiple condensing units and associated ductwork.

The building's management needed to determine whether the existing roof could be reinforced to carry the new loads, or whether a more extensive structural modification would be required. Without a proper engineering analysis and PE-stamped drawings, the DOB would not issue the permits needed to proceed with the installation, and the HVAC upgrade timeline was at risk of significant delay.

Adding to the complexity, the work needed to be designed in a way that would not disrupt the building's operations or require extensive interior construction. The management wanted a solution that would reinforce the roof from above, avoiding the need to access occupied residential units below the work area.

Our licensed engineers conducted a structural analysis of the existing roof framing to determine its current load capacity and identify the specific areas where reinforcement would be needed. This included a field survey of the existing structural members, a review of the original construction documents (where available), and load calculations based on the equipment manufacturer's specifications and NYC Building Code requirements.

Based on the analysis, our engineering team designed a steel reinforcement system that could be installed entirely from the roof level. The design used new steel beams spanning between existing structural walls to create dedicated equipment support platforms that would transfer the mechanical loads directly to the building's primary structure. PE-stamped engineering drawings were produced showing all structural details, connection specifications, and load paths.

We prepared and filed the complete DOB permit application, including the structural drawings, load calculations, and all required supporting documentation. Our team coordinated with the DOB examiner through the review process and addressed all comments to achieve permit approval. During construction, we provided periodic site visits to verify that the installation matched the approved drawings and issued a letter of completion upon final inspection.

The DOB permits were approved within the standard review timeline, keeping the HVAC upgrade on its original schedule. The structural reinforcement design met all code requirements while minimizing material and labor costs through efficient use of the existing structural capacity.

The installation was completed in 4 months from initial analysis through final sign-off. All work was performed from the roof level as planned, and no residential units were accessed or disrupted during the construction phase. The new mechanical equipment was installed and operational on the reinforced platforms without any issues.

The building received its final DOB sign-off confirming that all work was completed in accordance with the approved plans. The PE-stamped documentation package we provided gives the building a permanent structural record of the roof modifications, which will be valuable for any future rooftop work or equipment changes.