Tenmat’s FF102/50Plus Intumescent Fire Block was selected to fit a wide open-state cavity in a new-construction wastewater facility in Allegheny County, PA.
Strengthening Infrastructure for a Growing Community
Serving over 83 municipalities, including the city of Pittsburgh, ALCOSAN East Headworks plays a primary role in Allegheny County, Pennsylvania. By delivering 250 MGD (million gallons per day) to the county, ALCOSAN fuels its communities with treated water for its everyday usage. As the population continues to grow, the demand for treated water grows with it.
To meet future demand and improve system resiliency, ALCOSAN committed to a significant expansion of its operations. Once complete, the facility will be able to treat up to 600 million gallons per day (mgd)—an impressive increase of 350 mgd from its original capacity.
This milestone project represents a major investment in sustainable public infrastructure and reflects ALCOSAN’s long‑term commitment to the region’s environmental health and growth.
Design Decision Triggers New Compliance Requirements
As part of the expansion, the developer selected an engineered stone cladding system for the building façade. While offering durability and aesthetic advantages, this choice also triggered important fireblocking requirements under IBC Section 718.2.6 – Exterior Wall Coverings, which mandates proper fireblocking within exterior wall cavities when certain cladding materials are used. View the full IBC Section 718.2.6 Exterior Wall Coverings. By triggering this section of the code, ALCOSAN’s new expansion project will now require fireblocking in its exterior wall assembly.
A Unique Challenge: An Unusually Wide Ventilated Air Cavity
Unlike typical exterior wall assemblies, the engineered stone system incorporated a significantly wider ventilated air cavity. This design difference introduced a unique challenge. The wider cavity meant that the project team not only had to ensure fireblocking was installed but also had to identify a fireblocking solution capable of spanning the full width of the cavity—something standard fireblocking products are often not designed to accommodate.
This requirement added complexity to the assembly design, demanding a fireblocking material that could maintain code compliance, performance integrity, and seamless integration with the cladding system’s architectural intent.
Selecting a Fireblocking Solution Built for Performance
To meet both the requirements of IBC Section 718.2.6 and the unique width of the ventilated air cavity, the project team selected Tenmat’s FF102/50Plus Intumescent Fire Block for the ALCOSAN expansion. This solution offered the versatility and performance needed to accommodate the wider cavity while delivering reliable fire protection.
By integrating the FF102/50Plus into the wall assembly, ALCOSAN was able to confidently move forward with its preferred engineered stone cladding design. The fire block not only met the stringent fireblocking criteria required by code but also preserved the assembly’s airflow and moisture‑management performance, ensuring the durability and long‑term functionality of the exterior envelope.
