Case Study: NexSpan2™ F Series Cuts Time, Weight, and Cost for Rooftop Mechanical Skid

Project Overview

Location: Philadelphia, PA
Application: Rooftop mechanical skid for chilled water system
Products Used: NexSpan2™ F Series structural framing system

A leading mechanical contractor needed to support three chilled water pumps, a buffer tank, an air separator, an expansion tank, and a glycol fill tank on the roof of a five-story building in Philadelphia. Their initial design called for a welded steel skid, but concerns over installation time, weight, and cost drove them to seek alternatives.

The contractor reached out to Allfasteners with a rough design and asked whether the NexSpan2™ F Series framing system could be a viable substitute. The answer was yes.

Challenges

• Time-Intensive Welding: A fully welded skid would require approximately one week to fabricate, plus additional time for transport to and from a galvanizer.

• Weight Constraints: The skid needed to sit on rooftop structural dunnage, making overall weight a critical factor.

• Logistics: Rigging a heavy welded skid onto a five-story building required precision planning to minimize street closures and city disruption.

• Code Compliance: The structure had to meet stringent building codes, including wind and seismic requirements.

Allfasteners’ Solution

• Preliminary Design & Quote: Allfasteners provided a quick-turn preliminary design and cost estimate, confirming that NexSpan2™ F Series framing could meet the requirements.

• Engineering Collaboration: Partnering with in house engineering, Allfasteners helped ensure full compliance with building codes, attachment points, and rigging lift locations.

• Iterative Support: As PE analysis was finalized, Allfasteners revised member sizes and configurations to guarantee performance and safety.

• Fabrication Advantage: The NexSpan2™ F Series system was hot-dip galvanized prior to delivery, eliminating the need for the customer to send the frame out for coating.

_{Initial construction of NexSpan2™ F Series onsite.}

Results

• Faster Installation: The NexSpan2™ system was erected in less than two days—a process that would normally take over a week with welded steel.

• Cost Savings: Avoiding external galvanizing and reducing onsite labor time cut overall project costs.

• Lightweight & Strong: The system provided the necessary structural performance while reducing total weight compared to a fully welded alternative.

• Streamlined Logistics: With prefabrication completed in the shop, the contractor was able to conduct a successful test pick before transporting the skid to the jobsite.

• Smooth Rigging: The entire skid was lifted onto the roof with minimal disruption, including a temporary city street closure in Philadelphia.

• Adaptable Design: After installation, the contractor enclosed the frame with angles and sheet metal to create a weather-protected mechanical penthouse.

Customer Feedback

The contractor emphasized the time and efficiency gains:

“Normally this would take a week to weld and more time for galvanizing. With NexSpan2™, we had it fabricated, test-picked, and rigged to the roof in a fraction of the time.”

_{Finished project, fully sealed!}

Conclusion

By substituting the NexSpan2™ F Series framing system for a welded steel design, the contractor achieved:

• Significant time savings in fabrication and erection

• Reduced costs through elimination of galvanizing and excess labor

• Lightweight design suitable for rooftop installation

• Code-compliant engineering support ensuring safety and reliability

This project demonstrates how NexSpan2™ F Series delivers real-world value as a welded steel substitute—cutting installation time, reducing weight, and lowering costs while maintaining the strength and durability required for critical rooftop applications.