I appreciate the security concern from pb. I knew a roof top burglar who gained entry to downtown businesses by knocking out roof top vents or just chopping a hole in the roof. When he got caught he went to prison a couple times but he usually didn't get caught and found the old flat roofs surrounded by false fronts and sides to be easy pickens. He learned his trade from a relative of his.
I'm with Jim and shudder to think that I would want or need to turn my house into a sandbagged bunker. Although there are some people who live where they probably would want to.