Study on the Method of Improving the Fire Resistance Performance of No Threshold Fire Door

In this study, we aim to improve the fire resistance performance by solving the structural problem so that gas or flame does not leak through the door in case of a fire while maintaining airtightness and insulation when removing the threshold at the bottom of a general fire door. To improve airtightness and insulation performance along with fire-resistance, an ordinary auto-bottom is provided in the lower part of the door. However, there is a limit to securing fire-resistance. To maximize fire-resistance performance, graphite, an expandable foaming agent, is applied to block the gap between the lower part of the door and floor. Additionally, gas holes at the bottom of the door induce the gas generated to flow into the door. We found that blocking the flow of gas plays a very important role in improving fire-resistance performance.