Built to move: The difference behind Lamella in curtain wall fire protection

In facade design, passive fire protection must perform over time in real building conditions, not just in testing.

This is especially important in curtain wall construction, where facades accommodate movement from wind loads, thermal expansion, and structural deflection. In these cases, a firestop or perimeter seal must do more than fit at installation. It must maintain the seal over time as the building moves.

This is where a Lamella material offers something distinctly different.

Fire protection must do more than achieve fire resistance

Passive fire protection performance depends on more than fire rating alone. It must also maintain the right form, fit, and compressibility over the life of the system.

Some standard stone wool solutions use a horizontal fiber structure. While stable, this can reduce their ability to accommodate repeated lateral compression over time. As movement and compression continue, internal fiber bonds can break down, reducing the product’s ability to recover and potentially allowing gaps to form between the fire protection and the facade or slab edge.

In curtain wall systems, where movement is expected, that loss of recovery can become a critical performance issue. Passive fire protection must remain closely fitted between the facade and the floor slab or inner construction, maintaining integrity as those elements move relative to one another. If the material cannot flex, recover, and sustain contact, the long-term effectiveness of the seal may be at risk.

A material engineered differently

Siderise® developed its own unique Lamella to address these real-world demands. Rather than using a conventional horizontal fiber structure, Siderise Lamella is manufactured from a specially formulated stone wool with vertically oriented fibers. This vertical arrangement allows the product to better withstand lateral compression and to recover more reliably from movement. Accelerated age testing in accordance with EOTA Technical Report 024 has demonstrated that Siderise’s Lamella structure can be repeatedly laterally compressed without loss of recovery or flex.

A smarter experience on site

Lamella also brings practical advantages. The integrated foil facing is clearly marked on top/bottom, and with the fibers already oriented vertically, it significantly reduces the risk of installer error.

Traditional solutions can also require application of spray, with insulation cut and compressed onsite before being sealed with an elastomeric compound. Because Siderise’s product is pre-compressed in the factory, Lamella and the applied foil scrim provide such a high level of fire resistance that an additional wet seal is unnecessary. As that compression is applied, the facing visibly wrinkles, providing a visual indicator that the product has been installed correctly.

Built for the reality of modern facades

Siderise Lamella is engineered to maintain form, fit, and integrity in building envelope applications where movement is inevitable. In curtain wall systems, where small gaps can have significant consequences, that ability to move with the building is a critical performance requirement.

Learn more about the innovation behind Lamella at www.siderise-us.com/lamella