Smoke Gasketing

Smoke gasketing refers to sealing material, usually pile-fiber brush strips or flexible rubber blades, that is installed in or along the vertical guides of a rolling steel fire door. The seals press against the curtain edges, filling the small gap that naturally exists between the metal curtain slats and the guide channel.

A fire door's primary job is to block flame spread. But smoke and toxic gases kill people before fire does. They travel through gaps around door edges, especially in doors that are designed to coil and uncoil rather than sit perfectly flush in a frame. Smoke gasketing addresses those gaps.

Standard that governs it:

NFPA 105 is the standard for smoke door assemblies and other opening protectives. A rolling door labeled as an "S" assembly (smoke-rated) must include gasketing tested to limit air leakage to a maximum rate under pressure. Not every fire door needs smoke gasketing. A standard fire door rated only for flame spread (no "S" designation) may not include it. The listing label on the door tells you what it is rated for.

What it looks like:

Brush-type gasketing uses rows of nylon or polypropylene fibers packed into an aluminum channel that is screwed into the guide. The fibers flex as the curtain passes, maintaining contact without creating excessive drag on the curtain. Blade-type gasketing uses thin rubber wiper seals for tighter applications.

For example, a rolling fire door separating a commercial kitchen from a dining area may require an S rating. The gasketing runs the full height of both guides and along the head bar at the top of the door opening.

Proper function of smoke gasketing depends on the rolling door governor ensuring the curtain fully seats at the sill when it closes, since a curtain that stops short leaves the gasketing unable to make full contact.