5 March 2026
Accordion Fire Curtains for Architecturally Complex Openings
Wide spans, column-interrupted facades and irregular atrium boundaries defeat standard single-drop curtains. Accordion fire curtains fold to fit — here's how they work.
A standard automatic fire curtain deploys as a single flat sheet, descending vertically from a head box to seal a rectangular opening. This works for the majority of openings in a building. But architecture does not always provide rectangular openings — wide spans interrupted by structural columns, facades with stepped or angled geometry, and complex atrium boundaries with multiple changes of direction all defeat the basic assumption a single-drop curtain depends on: a clear, unobstructed vertical path for the fabric to descend.
When a Single-Drop Curtain Fails
If a structural column interrupts the line of an opening, a single-drop curtain either has to stop short of the column — leaving a gap in the fire barrier — or be split into separate curtains either side of the column, each requiring its own head box, guide rails and motor. For openings with more than one or two such interruptions, or for boundaries that change direction (an L-shaped or curved atrium edge, for example), this approach quickly becomes impractical, both in terms of cost and in terms of guaranteeing a continuous, gap-free seal.
How Accordion Curtains Work
Accordion fire curtains are manufactured in multiple folding panels connected along their vertical edges, allowing the assembly to deploy laterally or vertically across irregular openings and to change direction at the panel joints — sealing the full perimeter of a complex boundary without gaps, including around columns and at changes of facade angle. Construction follows the same principles as BÖLDT's standard automatic fire curtains: motorised operation with gravity fail-safe deployment, glass fabric with reinforced stainless steel wire, and aluminium or steel guide profiles matched to the opening's geometry.
Testing and Certification
Accordion fire curtains are tested and certified against the same EN 1634-1 methodology as BÖLDT's standard automatic curtains, with the multi-fold configuration assessed as a complete tested assembly rather than a series of independent panels. This is an important distinction for specifiers: a test report covering a flat single-drop curtain does not automatically extend to an accordion configuration, so the classification held must specifically reference the folded assembly being supplied.
Where Accordion Curtains Are Specified
- —Curved atrium boundaries and balustrade lines where a single flat curtain cannot follow the plan geometry.
- —Facades or openings interrupted by structural columns at irregular centres.
- —Stepped or raked openings in auditoriums, stadia and large-span assembly buildings.
- —Any compartment boundary where the architectural geometry rules out a flat fire curtain or a fixed wall.
BÖLDT manufactures accordion fire curtains in-house, tested to EN 1634-1 and rated up to 240 minutes, with the same gravity fail-safe deployment used across the standard automatic curtain range.
