Roof & crawlspace ventilation is a major reason for modern homes catching fire in the wildfires. Berkeley University has studied building practices and California has implemented building codes to protect your home from wildfire. This is the first site I've seen explained construction standards to prevent your home from catching fire in a wildfire. They talk about what I always thought was the most important, keeping the fire out of foundation and roof vents.
Information on this website was compiled by a number of people at University of California, Berkeley, and is based on input from fire tests, observations of wildfire damage, and input from those who are involved in firefighting. It is very important to realize that no (livable!) house is fire proof, but you can make it more fire-safe!
The website is organized to give you an opportunity to make changes to your home and the surroundings to reduce the possibility of damage from wildfires. Some of the changes can be done very quickly and relatively inexpensively. Others may require more effort, expense, and, in some cases, professional help.
The main part of the website begins with a list of features or parts that are of concern. If you click on any of these parts, you will go through a series of visual and text information on the specific item (say the roof or siding) that includes a definition of the possible problems and a discussion of potential solutions.