In high-pressure HVAC systems, the duct sealing process can determine whether a project finishes on time or stalls. Traditional liquid duct sealants may require up to 48 hours to cure before pressure testing. That’s manageable for new construction, but a serious limitation in facilities that need to be operation 24/7/365. In places such as hospitals, airports, train stations, delays can disrupt patient care, customer experience, and travel schedules

Delta Sheet Metal, a division of PJ Mechanical and one of the largest sheet metal contractors on the East Coast, knows this challenge well.

These compressed, time-sensitive windows are not only common for major hospital change-outs, but also for airports, and other large commercial buildings where HVAC systems must be back online before the facility reopens to the public.

Seal Right, Test Right Away

Part of PJ Mechanical’s full-service mechanical contracting operation, Delta Sheet Metal manages projects from fabrication through installation, commissioning, and maintenance. In both their shop and on jobsites, they switched from using liquid sealant on duct joints, with Hardcast^® FOIL-GRIP^® 1402 rolled mastic sealant.

“We have had such success with FOIL-GRIP that we have eliminated liquid sealant on all external connections,” Greenberg said. “Crews can pressure test the same day the sealant is applied, keeping projects on schedule while meeting strict leakage standards.”

“We have had such success with FOIL-GRIP that we have eliminated liquid sealant on all external connections,” Greenberg said. “Crews can pressure test the same day the sealant is applied, keeping projects on schedule while meeting strict leakage standards.”

FOIL-GRIP 1402 forms an instant weather-resistant seal on low- and medium-pressure ducts and is suitable for both indoor and outdoor use. It is rated for pressures up to 20 inches water gauge, which is higher than the operating pressure in most commercial HVAC duct systems. The foil-backed sealant also contains zero-VOCs, making it a safer choice for enclosed environments where air quality matters.

Precision in the Shop and the Field

Delta Sheet Metal’s fabrication process begins in its shop, where FOIL-GRIP 1402 is applied in the corners of unlined rectangular ductwork at the TDF (Transverse Duct Flange) connection and Pittsburgh seam, a folded joint used to lock sections of duct together. Applying FOIL-GRIP 1402 in these corners replaces a gasket, bridges unavoidable gaps, and ensures joints are sealed tight before they leave the floor.

For exterior ductwork, rolled mastic is applied over all seams to create a waterproof barrier that withstands UV exposure and weather extremes, extending system life. In the field, pairing FOIL-GRIP 1402 with proprietary gaskets and precision fastening has virtually eliminated leakage at connections, while reducing the likelihood of rework.

Greenberg said crews can complete installations that meet SMACNA (Sheet Metal and Air Conditioning Contractors’ National Association) seal class standards without the mess or inconsistency of brush-applied sealants.

Why Airtight Duct Sealing Matters

Improper sealing can result in 25-40 percent loss in HVAC system performance, according to industry studies¹. Air leakage increases energy consumption, places additional load on HVAC equipment, creates hot and cold spots, and reduces humidity control. In critical facilities, it can also compromise indoor air quality by allowing contaminants to enter the airstream.

By using FOIL-GRIP 1402 rolled mastic sealants, Delta addresses these issues at the source. The product’s consistent thickness and instant adhesion ensure joints are sealed right the first time, reducing the risk of callbacks. For clients, that translates to lower operating costs, better comfort, and more reliable system performance.

A Clean Finish That Lasts

Rolled mastic sealants also offer an appearance advantage. Available in unprinted rolls, the foil facer blends with duct surfaces for a clean, uniform look in exposed areas, such as mechanical rooms or open-ceiling designs. “FOIL-GRIP is something we can put our word behind,” said Greenberg. “It performs from day one and for years to come.”

The product’s zero-VOC composition makes it a strong fit for projects where sustainability and indoor environmental quality are priorities. It also helps meet LEED and other green building goals.

Performance That Builds Trust

Since they began using FOIL-GRIP 1402 rolled mastic sealants, Delta Sheet Metal has delivered same-day testing and airtight performance on projects ranging from hospital retrofits to major airport terminals.

“Consistent quality matters, regardless of project size,” Greenberg said. “We produce the highest quality solutions at scale, making us the trusted vendor of choice for many signature jobs in the New York Metropolitan Area.”

With FOIL-GRIP^® 1402, Delta consistently meets demanding project requirements while maintaining airtight performance that keeps HVAC systems running at peak efficiency. Hardcast delivers by helping contractors like them excel under pressure and ensuring every system is sealed right for the long term.

About Delta Sheet Metal

Delta Sheet Metal, a division of PJ Mechanical, is one of the largest and most advanced contractors serving the NYC and the metropolitan area. An all-encompassing service provider, their work includes single-floor buildouts, and multi-floor restacks for many of the largest projects in their market. Learn more.

About Carlisle HVAC

As an industry leader, Carlisle HVAC manufactures superior solutions to ensure peak duct system performance and sustainability. Our product brands include Hardcast^® (Duct Sealants & Adhesives), DynAir (Duct Airflow Hardware & Accessories), and Gripnail^® (Duct Insulation Fastening Equipment). Learn more.

¹ Source: Brookhaven National Laboratory Associated Universities, Incorporated
Department of Applied Science. Prepared for U.S. Department of Energy. DOE/EE0109. Revised November 1999. https://www1.eere.energy.gov/buildings/publications/pdfs/building_america/27630.pdf