Actually, what burns in a wildfire is much more about luck than anything. When I left my yard in 1993 during the Altadena Fire, the roof on the house across the street was on fire --with ten-foot flames shooting out under the tile -- 95% of the house didn't burn -- while every other house on the street--including mine--was burned to the ground.
At my sister's house, houses on all sides of her house were destroyed -- her house has some heat damage -- but it survived.
Sometimes, houses were saved because of goal-line stands by fire fighters and/or residents, but fire is much more fickle than you might think.
Mark