In short, building codes. Many years ago, DW and I were traveling through the hills around Malibu, and I was appalled by the number of cedar shake roof shingles I saw on houses. I don't think it is beyond the ken of man to establish building codes that will slow, or prevent, the spread of a fire to a home, and from home to home, in the conditions we are now seeing. Yes, it will cost more to construct, but the savings in lives and homes lost, is worth it.