EPS insulation is not fire resistant. It behaves like other hydrocarbons such as wood and paper when it is burning. When it’s exposed to temperatures around 100*C, it begins to soften, contract and eventually melt. The temperature, duration of exposure to heat and the oxygen availability play a key role in whether or not EPS can be ignited with a flame or a spark. EPS will ignite when exposed to an open flame and the temperature of this is around 360*C. Despite foam insulations being difficult to ignite, the burning will spread over the exposed surface until all of it is consumed. Once EPS is engulfed in flames, it will result in a dense smoke which leads to the release of Carbon Monoxide. It is important to note that Carbon Monoxide is emitted at various rates depending on the temperature of the fire and is far less toxic than when it is coming off EPS compared to other ‘natural’ building materials such as wood. Fire barriers are required due to the characteristics that EPS has, which allows it to burn.
Compared to EPS, K5 Kingspan insulation is fire resistant. Kingspan has a fire rating of 0. This means that the insulation has meet class 1 and also met the fire propagation requirements. Class 1 means the spread of flames is no greater than 165mm after 10 minutes of burning. Unlike EPS, the Kingspan does not become engulfed in flames which is what makes it fire resistant. Another benefit of K5 Kingspan compared to EPS is that Kingspan insulation has a better U-value. This means that it is a better material to insulate with as there is less heat loss.