The selection of materials for a fire door is a critical process focused on creating a complete assembly that can maintain its integrity and provide insulation against heat and flames for a mandated period,typically 20,60,90,or 120 minutes.The choice is not about a single material,but about a system of compatible components that work in unison.The primary goal is to specify materials that are non-combustible,possess high structural stability under thermal stress,and can accommodate the essential sealing mechanisms.
The core of the door,or the leaf,is most commonly constructed from steel or certified timber.Steel doors are typically fabricated from cold-rolled steel sheets,formed into a rigid frame and skin,and then filled with an insulating core material.This core is vital;it is not hollow and is instead packed with mineral wool,vermiculite board,or other proprietary fire-resistive materials that slow the transfer of heat.For wooden fire doors,the construction must be of solid-core type,using either solid timber or a manufactured timber core that has been treated and tested for fire resistance.These doors are engineered to char at a predictable rate,forming an insulating layer that protects the unburned wood beneath.Another option for areas requiring visibility is a fire-rated glazed door,which uses specialized ceramic or wire-reinforced glass set in a fire-rated frame.This glass is designed to withstand thermal shock and prevent breakthrough far longer than standard glass.
The supporting components are equally important and must be selected to match the fire rating of the door leaf.The frame must be made of materials with comparable fire resistance,such as heavy-gauge steel for metal doors or substantial,certified timber for wooden ones.All hardware,including hinges,latches,and locks,must be certified as fire-rated.These are often made from high-grade steel or alloys that can maintain strength and function at high temperatures,preventing the door from warping open.Finally,the intumescent seals are a material component of utmost importance.These strips,installed in the door or frame,are made from a graphite-based or other intumescent material that expands dramatically when heated,sealing the critical gaps around the door to block the passage of smoke and flames.The selection of the correct intumescent seal,compatible with the door and frame system,is a fundamental part of the material specification.