This Polystyrene panel was put in a household oven at 350º. For this reason, many polystyrene SIP manufacturers will not warrant application of roofing panels in the southwest and other hot climates where surface temperatures on roofs can reach upward of 300º.

As mentioned earlier, polyurethane is a thermal-set plastic and does not melt. It is not damaged until the temperature reaches 700º to 800º. and then it only "chars." This panel was subjected to the same test conditions as the polystyrene panel.