Study on the Fire Hazard of Insulation Installed Inside Apartment Ceilings - Based on the Top Floor

In older apartments, ceilings within units primarily contain lighting fixtures and wiring, resulting in low ceiling heights and minimal fire load. However, newer apartments often have higher ceilings due to HVAC installations and, on top floors, additional insulation, which increases fire load relative to the space's volume. This study examines the fire risk changes in ceiling spaces on the top floors of apartments built under modern insulation standards. A full-scale fire test was conducted using actual top-floor units and three common insulation types: EPS, XPS, and PIR. Results indicated that combustible insulations like EPS and XPS caused rapid fire spread with temperatures nearing 1,000°C, while semi-noncombustible PIR limited charring to within 1 meter of the ignition source. These findings confirm that insulation type significantly impacts fire risk. Since ceiling spaces in apartments resemble sandwich panels—with combustible insulation between noncombustible layers and potential ignition sources like electrical wiring—there is a high risk of fire ignition and spread. Therefore, stricter regulations on insulation materials are essential to reduce fire risks within apartment ceiling spaces.