Think about it like an electromagnetic field, where the probability of the house getting burned drops rapidly, inversely proportional to the square of the dista

Think about it like an electromagnetic field, where the probability of the house getting burned drops rapidly, inversely proportional to the square of the distance. So 30 feet is the minimum, 100 feet is even better, etc. If you read the article, the issue was embers floating the air and gathering on roofs and parts of the house that are not resistant to flames. So that's why the material has to be changed too, it's not about distance.