Doors stops are quite literally the section of a door frame that prevents a hinged door from over swinging and stops the door leaf at the appropriate closed position. They are the most protruding section of a door frame along the hinge, head and latch side of the assembly that provide a stopping surface and edge overlap.
The door stop dimension within the frame of a fire safety door assembly is a core component of how these doors achieve the required Fire Resistance Level also known as the FRL.
Standard door frames typically have a smaller door stop than those required in fire safety doors, as they simply need to solve the stopping function in order for the door to latch. However, in the case of fire doors the additional ability of preventing a fire from rapidly spreading is vital.
Therefore, ensuring the door stops and latches correctly is only one component of the door stop. The more important characteristic of the door stop in fire safety doors is to provide a sufficient overlapping surface, so that the door can be certified under stringent test conditions and meet Australian Standards.
In Australia the standard that governs the installation of Fire Safety Doors is AS1905.1. This standard outlines the gaps and tolerances, fitment and operation of fire safety doors, but does not dictate the material properties and dimensions of the products themselves. The second standard that comes into please is AS1530.4 which governs the testing of fire rated products and materials sold in Australia. This includes fire safety doors and how they must be tested to be certified to be sold with a minimum Fire Resistance Level (FRL).
Manufacturers selling fire doors must have the door products, they manufacturer, tested by registered laboratory testing providers such as CSIRO or Warrington Fire. Only once these independent laboratories certify the manufacturers doors under a full assembly scenario that replicates the installation conditions within a property, can it be sold to market.
Naturally to make the product as commercially viable as possible the goal is to achieve the highest possible fire rating of the product.
One of the easiest ways for the manufacturer to go about this is to arrange the testing conditions to be as advantageous as possible so the door leaf does not fail prematurely.
This is where manufacturers typically use 25mm dimension door stops in a steel frame that is backfilled with a suitable mortar or another material that protects the edge of the door leaf and minimizes heat transfer through the frame.
These conditions are then what dictate the precise installation requirements of the manufacturers product when fitted within properties throughout Australia.
To find out the installation methodology and frame requirements for a fire door, the distributor or manufacturer should be consulted directly as each product on the market often has its own unique requirements.
