Fire-Rated Steel Door

Overview

A fire door is a passive fire-protection product: a doorset certified to hold back flame, hot gas and smoke for a stated time, 30, 60 or 90 minutes, so that a building's compartments stay separated and escape routes stay usable. Everything about it is engineered around that single duty, and it is certified as a complete doorset (leaf, frame, seals and hardware tested together), not as parts mixed on site.

The barrier itself is the Door Leaf: two pressed steel skins folded around a solid Mineral Fire Core of non-combustible mineral board. The steel gives strength and the core gives insulation, it absorbs heat and keeps the unexposed face cool while the fire side glows. Internal Edge Stile stiles and Hardware Reinforcement plates are welded in so the hinges, lock and closer have solid metal to bite into. The leaf hangs in a welded Steel Door Frame whose rebated stop the leaf closes against and whose Strike Box contains the bolts.

How it works

The door's fire performance lives in the gaps. A closed leaf leaves a few millimetres of clearance all round, and in a fire that gap is the weak point. The Intumescent & Smoke Seal Set handles it two ways: brush Cold-Smoke Seal strips block cold smoke in the first minutes, then graphite Intumescent Strip swells to many times its size as it heats and chars the gap completely shut.

For the door to protect anything it must be closed, so a fire door is never left to chance. The Door Closer is an oil-damped overhead unit whose spring returns the leaf and drives the Mortise Lock & Latch latch home every time. Heavy Fire-Rated Hinge butts carry the weight through the fire. Where the design needs vision, a Vision Lite of fire-rated glass is bedded in intumescent tape so the aperture seals like the rest of the leaf; where air must transfer between rooms, a Transfer Louver with a fusible link and intumescent slats stays open in normal use but slams and seals shut on heat. The Door Hardware Set levers, strike and kick plate finish the doorset.