PVB Laminated Glass

PVB: The Default Interlayer

Polyvinyl butyral is the interlayer in the overwhelming majority of laminated glass, and has been since it became the standard for automotive windscreens in the 1930s. Nearly a century of use is a reasonable argument on its own.

Two sheets of glass are bonded to a PVB film under heat and pressure in an autoclave. The result behaves as one pane until it breaks, at which point the interlayer holds the fragments in place instead of letting them fall.

Thickness, and What It Is For

PVB comes in nominal plies of 0.38mm. A single ply is used in some interior applications. The standard for architectural safety glazing is 0.76mm — two plies. Security, hurricane and blast applications stack more.

Interlayer thickness matters more than people expect. On impact resistance it is often the governing variable rather than glass thickness, because it is the interlayer that has to stretch and hold.

Three Things PVB Does Well

It keeps the glass in the opening. This is the point. Tempered glass fails completely and leaves a hole. Laminated glass cracks and stays put — which is why it is the correct choice overhead, at height, in guards, and anywhere an opening must not be created.

It blocks ultraviolet. PVB absorbs the great majority of UV, which is why laminated glass is specified for display cases, galleries and anywhere fabric, timber or artwork sits behind the glass. Worth knowing that low-iron glass does not block UV — the interlayer does.

It damps sound. A single pane of glass resonates and re-radiates sound. The interlayer is viscoelastic and converts some of that vibration into heat instead. Standard PVB helps; acoustic-grade PVB is formulated specifically for it, with a softer core layer, and is what should be specified when noise is the actual problem. See our acoustic glass page.

Where PVB Gives Ground

It is sensitive to moisture at exposed edges. PVB absorbs water, and a laminated edge left permanently wet can delaminate — a milky haze creeping in from the edge. In framed glazing this is a non-issue. In open-edge applications such as balustrades, shelving or frameless partitions, edge protection matters, and it is one of the reasons SGP is often specified instead.

It softens at elevated temperature. PVB loses stiffness as it warms, so it is less suitable where the laminate is carrying structural load in a hot location.

It is not a security product on its own. Standard 0.76mm laminated glass delays an intruder; it does not stop one. Security glazing means more plies and thicker interlayers, and it is a different specification.

Where We Specify PVB

These describe the kind of work each area brings rather than any specific client project.

Acoustic work — hospital corridors, arterial roads, near the bridges and elevated lines. Acoustic-grade PVB in an asymmetric insulating unit is the correct answer for traffic and siren noise, and it outperforms adding a third pane.

Overhead and canopies — Manhattan retail frontage. Anything above a walkway should be laminated, so that a failure does not put glass on the pavement.

Guards and balustrades — Long Island City, Downtown Brooklyn, the waterfront. Laminated is required for guard glazing so the barrier survives a break. Where the edge is exposed, the interlayer choice is worth discussing.

Display and conservation — Museum Mile, the Chelsea galleries. UV rejection from the interlayer, clarity from a low-iron substrate. Both, not one instead of the other.

Ground floor and retail — Flatbush, Coney Island Avenue, the Diamond District. Laminated changes the arithmetic of a smash-and-grab by making the opening take repeated blows and noise rather than one.

Tell us what the glass has to survive and what should happen if it breaks. We supply and fabricate across Manhattan, Brooklyn, Queens, the Bronx and Staten Island, and throughout Northern New Jersey, the Jersey Shore, Philadelphia and the Lehigh Valley.