One of the topics brought up when introducing Spray foam to new customers is: “What happens to it during a fire, is it toxic?”
There are many variables to consider when answering this question, “Why?” you ask. Allow us to explain. Nearly every material in your home is considered toxic to your carbon monoxide. Carbon Monoxide (CO) & Carbon Dioxide (CO2) are by far the most abundant toxins produced in all fires. (CO) is considerably poisonous and causes the most fatalities of any toxins. So, the answer to your question is yes. Polyurethane does emit toxic fumes when burning and you should not be around it when on fire.
The same goes for most objects in your home (i.e. wood, plastic, linoleum, vinyl) because the toxicity of natural and synthetic materials, including polyurethane, is generally more similar than different. The difference between foam insulation and all other materials is, building code requires a fifteen-minute fire barrier to cover all foam in the walls and attic. This will give you time to escape the building before the fire even reaches the insulation.